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# IBM Cloudant Python SDK Version 0.9.3
IBM Cloudant Python SDK is a client library that interacts with the
[IBM Cloudant APIs](https://cloud.ibm.com/apidocs/cloudant?code=python).
Disclaimer: This library is still a 0.x release. We do consider this
library production-ready and capable, but there are still some
limitations we’re working to resolve, and refinements we want to
deliver. We are working really hard to minimise the disruption from
now until the 1.0 release, but there may still be some changes that
impact applications using this SDK. For now, be sure to pin versions
to avoid surprises.
<details>
<summary>Table of Contents</summary>
<!-- toc -->
- [Overview](#overview)
- [Features](#features)
- [Prerequisites](#prerequisites)
- [Installation](#installation)
- [Using the SDK](#using-the-sdk)
* [Authentication](#authentication)
+ [Authentication with environment variables](#authentication-with-environment-variables)
- [IAM API key authentication](#iam-api-key-authentication)
- [IAM Trusted profile (container) authentication](#iam-trusted-profile-container-authentication)
- [IAM Trusted profile (VPC) authentication](#iam-trusted-profile-vpc-authentication)
- [Session cookie authentication](#session-cookie-authentication)
+ [Authentication with external configuration](#authentication-with-external-configuration)
+ [Programmatic authentication](#programmatic-authentication)
* [Automatic retries](#automatic-retries)
* [Request timeout configuration](#request-timeout-configuration)
* [Code examples](#code-examples)
+ [1. Create a database and add a document](#1-create-a-database-and-add-a-document)
+ [2. Retrieve information from an existing database](#2-retrieve-information-from-an-existing-database)
+ [3. Update your previously created document](#3-update-your-previously-created-document)
+ [4. Delete your previously created document](#4-delete-your-previously-created-document)
+ [Further code examples](#further-code-examples)
* [Error handling](#error-handling)
* [Raw IO](#raw-io)
* [Model classes vs dictionaries](#model-classes-vs-dictionaries)
* [Further resources](#further-resources)
* [Changes feed follower (beta)](#changes-feed-follower-beta)
+ [Introduction](#introduction)
+ [Modes of operation](#modes-of-operation)
+ [Configuring the changes follower](#configuring-the-changes-follower)
+ [Error suppression](#error-suppression)
+ [Follower operation](#follower-operation)
+ [Checkpointing](#checkpointing)
+ [Code examples](#code-examples-1)
- [Initializing a changes follower](#initializing-a-changes-follower)
- [Starting the changes follower](#starting-the-changes-follower)
* [Start mode for continuous listening](#start-mode-for-continuous-listening)
* [Start mode for one-off fetching](#start-mode-for-one-off-fetching)
- [Processing changes](#processing-changes)
* [Process continuous changes](#process-continuous-changes)
* [Process one-off changes](#process-one-off-changes)
- [Stopping the changes follower](#stopping-the-changes-follower)
- [Questions](#questions)
- [Issues](#issues)
- [Versioning and LTS support](#versioning-and-lts-support)
- [Open source at IBM](#open-source-at-ibm)
- [Contributing](#contributing)
- [License](#license)
</details>
## Overview
The IBM Cloudant Python SDK allows developers to programmatically
interact with [IBM Cloudant](https://cloud.ibm.com/apidocs/cloudant)
with the help of the `ibmcloudant` package.
## Features
The purpose of this Python SDK is to wrap most of the HTTP request APIs
provided by Cloudant and supply other functions to ease the usage of Cloudant.
This SDK should make life easier for programmers to do what’s really important
to them: developing software.
Reasons why you should consider using Cloudant Python SDK in your
project:
- Supported by IBM Cloudant.
- Server compatibility with:
- IBM Cloudant.
- [Apache CouchDB 3.x](https://docs.couchdb.org/en/stable/) for data operations.
- Includes all the most popular and latest supported endpoints for
applications.
- Handles the authentication.
- Familiar user experience with IBM Cloud SDKs.
- Flexibility to use either built-in models or byte-based requests and responses for documents.
- Built-in [Changes feed follower](#changes-feed-follower-beta) (beta)
- Instances of the client are unconditionally thread-safe.
## Prerequisites
- A
[Cloudant](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-getting-started-with-cloudant)
service instance or a
[CouchDB](https://docs.couchdb.org/en/latest/install/index.html)
server.
- Python 3.9 or above.
## Installation
To install, use `pip` or `easy_install`:
```bash
pip install --upgrade "ibmcloudant>=0.9.3"
```
or
```bash
easy_install --upgrade "ibmcloudant>=0.9.3"
```
## Using the SDK
For fundamental SDK usage information and config options, please see the common [IBM Cloud SDK](https://github.com/IBM/ibm-cloud-sdk-common/blob/main/README.md) documentation.
This library requires configuration with a service URL and
[Cloudant service credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-locating-your-service-credentials) to authenticate with your
account.
There are several ways to **set** these authentication properties:
1. As [environment variables](#authentication-with-environment-variables)
2. The [programmatic approach](#programmatic-authentication)
3. With an [external credentials file](#authentication-with-external-configuration)
The following section describes the different authentication types and provides environment variable examples.
Examples for other configuration methods are available by following the provided links.
### Authentication
This library requires credentials to authenticate with IBM Cloudant. These credentials may be:
* IBM Cloud IAM credentials (can be used with authentication types `CONTAINER`, `VPC` and `IAM`)
* [IBM Cloud account](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-managing-access-for-cloudant#introduction-iam-ai) user, service ID or trusted profile credentials
that have been granted access to the IBM Cloud Cloudant resource instance.
* [IBM Cloudant service credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-locating-your-service-credentials) generated by the IBM Cloud Cloudant resource instance.
* Username and password credentials (can be used with authentication types `COUCHDB_SESSION` and `BASIC`)
* [IBM Cloudant service credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-locating-your-service-credentials) generated for an IBM Cloud Cloudant resource instance not configured as `IAM only`.
* IBM Cloudant [legacy credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-work-with-your-account#basic-authentication) (i.e. username and password) for instances not in IBM Cloud.
* IBM Cloudant [legacy API keys](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-work-with-your-account#api-keys).
For other compatible APIs that are not Cloudant accounts (e.g. Apache CouchDB) non-IAM based authentication types
must be used.
This table summarizes the available authentication types.
The authentication types are listed in order of recommendation, preferably use the authentication type
from the first row in the table that is compatible with your environment.
| Authentication type | Recommended for | `AUTH_TYPE` | Description |
| --- | --- | --- | --- |
| IAM Trusted Profiles compute resource ([container](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#container-authentication)) | Cloudant<BR>(SDK running in IBM Cloud IKS) | `CONTAINER` | Obtains a compute resource (CR) token from the container.<BR>Exchanges the CR token for an IAM `access_token`.<BR>Adds an `Authorization: Bearer <access_token>` header to each HTTP request.<BR>Automatically renews the access token when needed. |
| IAM Trusted Profiles compute resource ([VPC](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#vpc-instance-authentication)) | Cloudant<BR>(SDK running in IBM Cloud VPC) | `VPC` | Obtains an identity token from the VPC instance metadata.<BR>Exchanges the identity token for an IAM `access_token`.<BR>Adds an `Authorization: Bearer <access_token>` header to each HTTP request.<BR>Automatically renews the access token when needed. |
| [IAM API key](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#identity-and-access-management-iam-authentication) | Cloudant | `IAM` | Exchanges an IAM API key for an IAM `access_token`.<BR>Adds an `Authorization: Bearer <access_token>` header to each HTTP request.<BR>Automatically renews the access token when needed. |
| [Session cookie](#session-cookie-authentication) | [Cloudant](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-work-with-your-account#cookie-authentication)<BR>(legacy credentials & instances without IAM)<BR><BR>[Apache CouchDB](https://docs.couchdb.org/en/stable/api/server/authn.html#cookie-authentication) | `COUCHDB_SESSION` | Exchanges credentials with `/_session` endpoint to retrieve a cookie.<BR>Adds `Cookie` header and content to each HTTP request.<BR>Automatically renews session when needed. |
| [Bearer token](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#bearer-token-authentication) | [Apache CouchDB](https://docs.couchdb.org/en/stable/api/server/authn.html#jwt-authentication)<BR>(using JWT authentication) | `BEARERTOKEN` | Adds an `Authorization: Bearer <token>` to each HTTP request.<BR>No token management or renewal.<BR>Also compatible with IAM access tokens managed independently of the SDK. |
| [Basic](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#basic-authentication) | [Apache CouchDB](https://docs.couchdb.org/en/stable/api/server/authn.html#basic-authentication)<BR>(if cookies are not enabled) | `BASIC` | Adds an `Authorization: Basic <encoded username and password>` header to each HTTP request. |
| [None](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#no-auth-authentication) | - | `NOAUTH` | Note that this authentication type only works for operations against a database allowing access for unauthenticated users. |
The default authentication type for the SDK is `CONTAINER` unless `APIKEY` configuration is supplied, which changes the default authentication type to `IAM`.
#### Authentication with environment variables
The default service name is `CLOUDANT` so `CLOUDANT_` prefixed names are used in these examples.
Any custom service name prefix can be used as long as the matching name is used to instantiate the SDK client
and the same prefix is used for all configuration options.
##### IAM API key authentication
For Cloudant *IAM API key authentication*, set the following environmental variables by
replacing the `<url>` and `<apikey>` with your proper
[service credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-locating-your-service-credentials). There is no need to set
`CLOUDANT_AUTH_TYPE` to `IAM` because it is the default when an `APIKEY` is set.
```bash
CLOUDANT_URL=<url>
CLOUDANT_APIKEY=<apikey>
```
##### IAM Trusted profile (container) authentication
For Cloudant *IAM Trusted profile compute resource container authentication*, set the following environmental variables by
replacing the `<url>` and `<id>` with your values. There is no need to set
`CLOUDANT_AUTH_TYPE` to `CONTAINER` because it is the default.
```bash
CLOUDANT_URL=<url>
CLOUDANT_IAM_PROFILE_ID=<id>
```
Alternatively a profile name may be used instead of an ID by replacing `CLOUDANT_IAM_PROFILE_ID` with `CLOUDANT_IAM_PROFILE_NAME`.
##### IAM Trusted profile (VPC) authentication
For Cloudant *IAM Trusted profile compute resource vpc authentication*, set the following environmental variables by
replacing the `<url>` and `<id>` with your values.
```bash
CLOUDANT_AUTH_TYPE=VPC
CLOUDANT_URL=<url>
CLOUDANT_IAM_PROFILE_ID=<id>
```
Alternatively a profile CRN may be used instead of an ID by replacing `CLOUDANT_IAM_PROFILE_ID` with `CLOUDANT_IAM_PROFILE_CRN`.
##### Session cookie authentication
For `COUCHDB_SESSION` authentication, set the following environmental variables
by replacing the `<url>`, `<username>` and `<password>` with your proper
[service credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-locating-your-service-credentials).
```bash
CLOUDANT_AUTH_TYPE=COUCHDB_SESSION
CLOUDANT_URL=<url>
CLOUDANT_USERNAME=<username>
CLOUDANT_PASSWORD=<password>
```
#### Authentication with external configuration
To use an external configuration file, the
[Cloudant API docs](https://cloud.ibm.com/apidocs/cloudant?code=python#authentication-with-external-configuration),
or the
[general SDK usage information](https://github.com/IBM/ibm-cloud-sdk-common#using-external-configuration)
will guide you.
#### Programmatic authentication
To learn more about how to use programmatic authentication, see the related
documentation in the
[Cloudant API docs](https://cloud.ibm.com/apidocs/cloudant?code=python#programmatic-authentication)
or in the
[Python SDK Core document](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md) about authentication.
### Automatic retries
The SDK supports a generalized retry feature that can automatically retry on common errors.
The [automatic retries](https://github.com/IBM/ibm-cloud-sdk-common#automatic-retries) section has details on how to enable the retries with default values and customize the retries programmatically or with external configuration.
### Request timeout configuration
No request timeout is defined, but a 2.5m read and a 60s connect timeout are set by default. Be sure to set a request timeout appropriate to your application usage and environment.
The [request timeout](https://github.com/IBM/ibm-cloud-sdk-common#configuring-request-timeouts) section contains details on how to change the value.
**Note:** System settings may take precedence over configured timeout values.
### Code examples
The following code examples
[authenticate with the environment variables](#authentication-with-environment-variables).
#### 1. Create a database and add a document
**Note:** This example code assumes that `orders` database does not exist in your account.
This example code creates `orders` database and adds a new document "example"
into it. To connect, you must set your environment variables with
the *service url*, *authentication type* and *authentication credentials*
of your Cloudant service.
Cloudant environment variable naming starts with a *service name* prefix that identifies your service.
By default, this is `CLOUDANT`, see the settings in the
[authentication with environment variables section](#authentication-with-environment-variables).
If you would like to rename your Cloudant service from `CLOUDANT`,
you must use your defined service name as the prefix for all Cloudant related environment variables.
Once the environment variables are set, you can try out the code examples.
```py
from ibm_cloud_sdk_core import ApiException
from ibmcloudant.cloudant_v1 import CloudantV1, Document
# 1. Create a client with `CLOUDANT` default service name =============
client = CloudantV1.new_instance()
# 2. Create a database ================================================
example_db_name = "orders"
# Try to create database if it doesn't exist
try:
put_database_result = client.put_database(
db=example_db_name
).get_result()
if put_database_result["ok"]:
print(f'"{example_db_name}" database created.')
except ApiException as ae:
if ae.status_code == 412:
print(f'Cannot create "{example_db_name}" database, ' +
'it already exists.')
# 3. Create a document ================================================
# Create a document object with "example" id
example_doc_id = "example"
# Setting `id` for the document is optional when "post_document"
# function is used for CREATE. When `id` is not provided the server
# will generate one for your document.
example_document: Document = Document(id=example_doc_id)
# Add "name" and "joined" fields to the document
example_document.name = "Bob Smith"
example_document.joined = "2019-01-24T10:42:59.000Z"
# Save the document in the database with "post_document" function
create_document_response = client.post_document(
db=example_db_name,
document=example_document
).get_result()
# =====================================================================
# Note: saving the document can also be done with the "put_document"
# function. In this case `doc_id` is required for a CREATE operation:
"""
create_document_response = client.put_document(
db=example_db_name,
doc_id=example_doc_id,
document=example_document
).get_result()
"""
# =====================================================================
# Keeping track of the revision number of the document object
# is necessary for further UPDATE/DELETE operations:
example_document.rev = create_document_response["rev"]
print(f'You have created the document:\n{example_document}')
```
When you run the code, you see a result similar to the following output.
```text
"orders" database created.
You have created the document:
{
"_id": "example",
"_rev": "1-1b403633540686aa32d013fda9041a5d",
"name": "Bob Smith",
"joined": "2019-01-24T10:42:99.000Z"
}
```
#### 2. Retrieve information from an existing database
**Note**: This example code assumes that you have created both the `orders`
database and the `example` document by
[running the previous example code](#1-create-a-database-and-add-a-document)
successfully. Otherwise, the following error message occurs, "Cannot delete document because either 'orders'
database or 'example' document was not found."
<details>
<summary>Gather database information example</summary>
```py
import json
from ibmcloudant.cloudant_v1 import CloudantV1
# 1. Create a client with `CLOUDANT` default service name ============
client = CloudantV1.new_instance()
# 2. Get server information ===========================================
server_information = client.get_server_information(
).get_result()
print(f'Server Version: {server_information["version"]}')
# 3. Get database information for "orders" ==========================
db_name = "orders"
db_information = client.get_database_information(
db=db_name
).get_result()
# 4. Show document count in database ==================================
document_count = db_information["doc_count"]
print(f'Document count in \"{db_information["db_name"]}\" '
f'database is {document_count}.')
# 5. Get "example" document out of the database by document id ============
document_example = client.get_document(
db=db_name,
doc_id="example"
).get_result()
print(f'Document retrieved from database:\n'
f'{json.dumps(document_example, indent=2)}')
```
</details>
When you run the code, you see a result similar to the following output.
```text
Server Version: 2.1.1
Document count in "orders" database is 1.
Document retrieved from database:
{
"_id": "example",
"_rev": "1-1b403633540686aa32d013fda9041a5d",
"name": "Bob Smith",
"joined": "2019-01-24T10:42:99.000Z"
}
```
#### 3. Update your previously created document
**Note**: This example code assumes that you have created both the `orders`
database and the `example` document by
[running the previous example code](#1-create-a-database-and-add-a-document)
successfully. Otherwise, the following error message occurs, "Cannot update document because either 'orders'
database or 'example' document was not found."
<details>
<summary>Update code example</summary>
```py
import json
from ibm_cloud_sdk_core import ApiException
from ibmcloudant.cloudant_v1 import CloudantV1
# 1. Create a client with `CLOUDANT` default service name =============
client = CloudantV1.new_instance()
# 2. Update the document ==============================================
example_db_name = "orders"
example_doc_id = "example"
# Try to get the document if it previously existed in the database
try:
document = client.get_document(
db=example_db_name,
doc_id=example_doc_id
).get_result()
# =================================================================
# Note: for response byte stream use:
"""
document_as_byte_stream = client.get_document_as_stream(
db=example_db_name,
doc_id=example_doc_id
).get_result()
"""
# =================================================================
# Add Bob Smith's address to the document
document["address"] = "19 Front Street, Darlington, DL5 1TY"
# Remove the joined property from document object
if "joined" in document:
document.pop("joined")
# Update the document in the database
update_document_response = client.post_document(
db=example_db_name,
document=document
).get_result()
# =================================================================
# Note 1: for request byte stream use:
"""
update_document_response = client.post_document(
db=example_db_name,
document=document_as_byte_stream
).get_result()
"""
# =================================================================
# =================================================================
# Note 2: updating the document can also be done with the
# "put_document" function. `doc_id` and `rev` are required for an
# UPDATE operation, but `rev` can be provided in the document
# object as `_rev` too:
"""
update_document_response = client.put_document(
db=example_db_name,
doc_id=example_doc_id, # doc_id is a required parameter
rev=document["_rev"],
document=document # _rev in the document object CAN replace above `rev` parameter
).get_result()
"""
# =================================================================
# Keeping track of the latest revision number of the document
# object is necessary for further UPDATE/DELETE operations:
document["_rev"] = update_document_response["rev"]
print(f'You have updated the document:\n' +
json.dumps(document, indent=2))
except ApiException as ae:
if ae.status_code == 404:
print('Cannot delete document because either ' +
f'"{example_db_name}" database or "{example_doc_id}" ' +
'document was not found.')
```
</details>
When you run the code, you see a result similar to the following output.
```text
{
"_id": "example",
"_rev": "2-4e2178e85cffb32d38ba4e451f6ca376",
"name": "Bob Smith",
"address": "19 Front Street, Darlington, DL5 1TY"
}
```
#### 4. Delete your previously created document
**Note**: This example code assumes that you have created both the `orders`
database and the `example` document by
[running the previous example code](#1-create-a-database-and-add-a-document)
successfully. Otherwise, the following error message occurs, "Cannot delete document because either 'orders'
database or 'example' document was not found."
<details>
<summary>Delete code example</summary>
```py
from ibm_cloud_sdk_core import ApiException
from ibmcloudant.cloudant_v1 import CloudantV1
# 1. Create a client with `CLOUDANT` default service name =============
client = CloudantV1.new_instance()
# 2. Delete the document ==============================================
example_db_name = "orders"
example_doc_id = "example"
# Try to get the document if it previously existed in the database
try:
document = client.get_document(
db=example_db_name,
doc_id=example_doc_id
).get_result()
delete_document_response = client.delete_document(
db=example_db_name,
doc_id=example_doc_id, # `doc_id` is required for DELETE
rev=document["_rev"] # `rev` is required for DELETE
).get_result()
if delete_document_response["ok"]:
print('You have deleted the document.')
except ApiException as ae:
if ae.status_code == 404:
print('Cannot delete document because either ' +
f'"{example_db_name}" database or "{example_doc_id}"' +
'document was not found.')
```
</details>
When you run the code, you see the following output.
```text
You have deleted the document.
```
#### Further code examples
For a complete list of code examples, see the [examples directory](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/examples#examples-for-python).
### Error handling
For sample code on handling errors, see
[Cloudant API docs](https://cloud.ibm.com/apidocs/cloudant?code=python#error-handling).
### Raw IO
For endpoints that read or write document content it is possible to bypass
usage of the built-in object with byte streams.
Depending on the specific SDK operation it may be possible to:
* accept a user-provided byte stream to send to the server as a request body
* return a byte stream of the server response body to the user
Request byte stream can be supplied for arguments that accept the `BinaryIO` type.
For these cases you can pass this byte stream directly to the HTTP request body.
Response byte stream is supported in functions with the suffix of `_as_stream`.
The returned byte stream allows the response body to be consumed
without triggering JSON unmarshalling that is typically performed by the SDK.
The [update document](#3-update-your-previously-created-document) section
contains examples for both request and response byte stream cases.
The API reference contains further examples of using byte streams.
They are titled "Example request as stream" and are initially collapsed.
Expand them to see examples of:
- Byte requests:
- [Bulk modify multiple documents in a database](https://cloud.ibm.com/apidocs/cloudant?code=python#postbulkdocs)
- Byte responses:
- [Query a list of all documents in a database](https://cloud.ibm.com/apidocs/cloudant?code=python#postalldocs)
- [Query the database document changes feed](https://cloud.ibm.com/apidocs/cloudant?code=python#postchanges)
### Model classes vs dictionaries
This SDK supports two possible formats to define an HTTP request. One approach uses only model classes and the other only dictionaries.
<details>
<summary>Example using model class structure</summary>
```py
from ibmcloudant.cloudant_v1 import DesignDocument, CloudantV1, DesignDocumentOptions, SearchIndexDefinition
client = CloudantV1.new_instance()
price_index = SearchIndexDefinition(
index='function (doc) { index("price", doc.price); }'
)
design_document_options = DesignDocumentOptions(
partitioned=True
)
partitioned_design_doc = DesignDocument(
indexes={'findByPrice': price_index},
options=design_document_options
)
response = client.put_design_document(
db='products',
design_document=partitioned_design_doc,
ddoc='appliances'
).get_result()
print(response)
```
</details>
<details>
<summary>Same example using dictionary structure</summary>
```py
from ibmcloudant.cloudant_v1 import CloudantV1
client = CloudantV1.new_instance()
price_index = {
'index': 'function (doc) { index("price", doc.price); }'
}
partitioned_design_doc = {
'indexes': {'findByPrice': price_index},
'options': {'partitioned': True},
}
response = client.put_design_document(
db='products',
design_document=partitioned_design_doc,
ddoc='appliances'
).get_result()
print(response)
```
</details>
Since model classes and dicts are different data structures, they cannot be combined.
<details>
<summary>This solution will be invalid</summary>
```py
from ibmcloudant.cloudant_v1 import CloudantV1, DesignDocument
client = CloudantV1.new_instance()
price_index = {
'index': 'function (doc) { index("price", doc.price); }'
}
partitioned_design_doc = DesignDocument(
indexes={'findByPrice': price_index},
options={'partitioned': True}
)
response = client.put_design_document(
db='products',
design_document=partitioned_design_doc,
ddoc='appliances'
).get_result()
print(response)
```
</details>
### Further resources
- [Cloudant API docs](https://cloud.ibm.com/apidocs/cloudant?code=python):
API reference including usage examples for Cloudant Python SDK API.
- [Pydoc](https://ibm.github.io/cloudant-python-sdk/):
Cloudant Python SDK API Documentation.
- [Cloudant docs](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-getting-started-with-cloudant):
The official documentation page for Cloudant.
- [Cloudant blog](https://blog.cloudant.com/):
Many useful articles about how to optimize Cloudant for common problems.
### Changes feed follower (beta)
#### Introduction
The SDK provides a changes feed follower utility (currently beta).
This helper utility connects to the `_changes` endpoint and returns the individual change items.
It removes some of the complexity of using the `_changes` endpoint by setting some options automatically
and providing error suppression and retries.
*Tip: the changes feed often does not meet user expectations or assumptions.*
Consult the [Cloudant changes feed FAQ](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-faq-using-changes-feed)
to get a better understanding of the limitations and suitable use-cases before using the changes feed in your application.
#### Modes of operation
There are two modes of operation:
* Start mode
* Fetches the changes from the supplied `since` sequence (by default the feed will start from `now`).
* Fetches all available changes and then continues listening for new changes indefinitely unless encountering an end condition.
* An example use case for this mode is event driven workloads.
* Start one-off mode
* Fetches the changes from the supplied `since` sequence (by default the feed will start from the beginning).
* Fetches all available changes and then stops when either there are no further changes pending or encountering an end condition.
* An example use case for this mode is ETL style workloads.
#### Configuring the changes follower
The SDK's model of changes feed options is also used to configure the follower.
However, a subset of the options are invalid as they are configured internally by the implementation.
Supplying these options when instantiating the follower causes an error.
The invalid options are:
* `descending`
* `feed`
* `heartbeat`
* `lastEventId` - use `since` instead
* `timeout`
* Only the value of `_selector` is permitted for the `filter` option. This restriction is because selector
based filters perform better than JavaScript backed filters. Configuring a non-selector based filter will
cause the follower to error.
Note that the `limit` parameter will terminate the follower at the given number of changes in either
operating mode.
The changes follower requires the client to have HTTP timeouts of at least 1 minute and will error during
instantiation if it is insufficient. The default client configuration has sufficiently long timeouts.
For use-cases where these configuration limitations are deemed too restrictive then it is recommended to
write code to use the SDK's [POST `_changes` API](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/examples#postchanges) instead of the follower.
#### Error suppression
By default, the changes follower will suppress transient errors indefinitely and attempt to run to completion or listen forever as
dictated by the operating mode.
For applications where that is not desirable an optional error tolerance duration may be specified to control the time since
the last successful response that transient errors will be suppressed. This can be used, for example, by applications as a grace period
before reporting an error and requiring intervention.
There are some additional points to consider for error suppression:
* Errors considered terminal, for example, the database not existing or invalid credentials are never suppressed and will error immediately.
* The error suppression duration is not guaranteed to fire immediately after lapsing and should be considered a minimum suppression time.
* The changes follower will back-off between retries and as such may remain paused for a short while after the transient errors have resolved.
* If the underlying SDK client used to initialize the follower also has retries configured then errors could be suppressed for significantly
longer than the follower's configured error tolerance duration depending on the configuration options.
#### Follower operation
For both modes:
* The end conditions are:
* A terminal error (HTTP codes `400`, `401`, `403` `404`).
* Transient errors occur for longer than the error tolerance duration. Transient errors are all other HTTP status codes and connection errors.
* The number of changes received reaches the configured `limit`.
* The feed is terminated early by calling stop.
As is true for the `_changes` endpoint change items have *at least once* delivery and an individual item
may be received multiple times. When using the follower change items may be repeated even within a limited
number of changes (i.e. using the `limit` option) this is a minor difference from using `limit` on the HTTP native API.
The follower is not optimized for some use cases and it is not recommended to use it in cases where:
* Setting `include_docs` and larger document sizes (for example > 10 kiB).
* The volume of changes is very high (if the rate of changes in the database exceeds the follower's rate of pulling them it will never catch-up).
In these cases use-case specific control over the number of change requests made and the content size of the responses
may be achieved by using the SDK's [POST `_changes` API](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/examples#postchanges).
#### Checkpointing
The changes follower does not checkpoint since it has no information about whether a change item has been
processed by the consuming application after being received. It is the application developer's responsibility
to store the sequence IDs to have appropriate checkpoints and to re-initialize the follower with the required
`since` value after, for example, the application restarts.
The frequency and conditions for checkpointing are application specific and some applications may be tolerant
of dropped changes. This section is intended only to provide general guidance on how to avoid missing changes.
To guarantee processing of all changes the sequence ID from a change item must not be persisted until *after*
the processing of the change item by the application has completed. As indicated previously change items are
delivered *at least once* so application code must be able to handle repeated changes already and it is
preferable to restart from an older `since` value and receive changes again than risk missing them.
The sequence IDs are available on each change item by default, but may be omitted from some change items when
using the `seq_interval` configuration option. Infrequent sequence IDs may improve performance by reducing
the amount of data that needs to be transferred, but the trade-off is that more changes will be repeated if
it is necessary to resume the changes follower.
Extreme care should be taken with persisting sequences if choosing to process change items in parallel as there
is a considerable risk of missing changes on a restart if the sequence is recorded out of order.
#### Code examples
##### Initializing a changes follower
```py
import ChangesFollower
from ibmcloudant.cloudant_v1 import CloudantV1
client = CloudantV1.new_instance()
cf_params = {
'db': 'example', # Required: the database name.
'limit': 100, # Optional: return only 100 changes (including duplicates).
'since': '3-g1AG3...' # Optional: start from this sequence ID (e.g. with a value read from persistent storage).
}
changes_follower = ChangesFollower(
service=client, # Required: the Cloudant service client instance.
error_tolerance=10000, # Optional: suppress transient errors for at least 10 seconds before terminating.
**cf_params # Required: changes feed configuration options dict.
)
```
##### Starting the changes follower
###### Start mode for continuous listening
```py
import Iterable
from ibmcloudant import ChangesFollower
from ibmcloudant.cloudant_v1 import CloudantV1, ChangesResultItem
client = CloudantV1.new_instance()
changes_follower = ChangesFollower(
service=client,
**{'db': 'example'})
changes_items: Iterable[ChangesResultItem] = changes_follower.start()
# Note: iterable will not do anything until it is iterated
# Create a for loop to iterate over the flow of changes
# for changes_item in changes_items: ...
```
###### Start mode for one-off fetching
```py
import Iterable
from ibmcloudant import ChangesFollower
from ibmcloudant.cloudant_v1 import CloudantV1, ChangesResultItem
client = CloudantV1.new_instance()
changes_follower = ChangesFollower(
service=client,
**{'db': 'example'})
changes_items: Iterable[ChangesResultItem] = changes_follower.start_one_off()
# Note: iterable will not do anything until it is iterated
# Create a for loop to iterate over the flow of changes
# for changes_item in changes_items: ...
```
##### Processing changes
###### Process continuous changes
```py
import ChangesFollower
from ibmcloudant.cloudant_v1 import CloudantV1
client = CloudantV1.new_instance()
# Start from a previously persisted seq
# Normally this would be read by the app from persistent storage
# e.g. previously_persisted_seq = your_app_persistence_read_func()
previously_persisted_seq = '3-g1AG3...'
changes_follower = ChangesFollower(
service=client,
**{'db': 'example', 'since': previously_persisted_seq})
changes_items = changes_follower.start()
for changes_item in changes_items:
# do something with changes
print(changes_item.id)
for change in changes_item.changes:
print(change.rev)
# when change item processing is complete app can store seq
seq = changes_item.seq
# write seq to persistent storage for use as since if required to resume later
# e.g. your_app_persistence_write_func(seq)
# keep processing changes until the application is terminated or some other stop condition is reached
# Note: iterator above is blocking, code here will be unreachable
# until the iteration is stopped or another stop condition is reached.
# For long running followers careful consideration should be made of where to call stop on the iterator.
```
###### Process one-off changes
```py
import ChangesFollower
from ibmcloudant.cloudant_v1 import CloudantV1
client = CloudantV1.new_instance()
# Start from a previously persisted seq
# Normally this would be read by the app from persistent storage
# e.g. previously_persisted_seq = your_app_persistence_read_func()
previously_persisted_seq = '3-g1AG3...'
changes_follower = ChangesFollower(
service=client,
**{'db': 'example', 'since': previously_persisted_seq})
changes_items = changes_follower.start_one_off()
for changes_item in changes_items:
# do something with changes
print(changes_item.id)
for change in changes_item.changes:
print(change.rev)
# when change item processing is complete app can store seq
seq = changes_item.seq
# write seq to persistent storage for use as since if required to resume later
# e.g. your_app_persistence_write_func(seq)
# Note: iterator above is blocking, code here will be unreachable
# until all changes are processed (or another stop condition is reached).
```
##### Stopping the changes follower
```py
import ChangesFollower
from ibmcloudant.cloudant_v1 import CloudantV1
client = CloudantV1.new_instance()
changes_follower = ChangesFollower(
service=client,
**{'db': 'example'})
changes_items = changes_follower.start()
for changes_item in changes_items:
# Option 1: call stop after some condition
# Note that since the iterator is blocking at least one item
# must be returned from it to reach to this point.
# Additional changes may be processed before the iterator stops.
changes_follower.stop()
# Option 2: call stop method when you want to end the continuous loop from
# outside the iterator. For example, you've put the changes follower in a
# separate thread and need to call stop on the main thread.
# Note: in this context the call must be made from a different thread because
# code immediately following the iterator is unreachable until the iterator
# has stopped.
changes_follower.stop()
```
## Questions
If you are having difficulties using this SDK or have a question about the
IBM Cloud services, ask a question on
[Stack Overflow](http://stackoverflow.com/questions/ask?tags=ibm-cloud).
## Issues
If you encounter an issue with the project, you are welcome to submit a
[bug report](https://github.com/IBM/cloudant-python-sdk/issues).
Before you submit a bug report, search for
[similar issues](https://github.com/IBM/cloudant-python-sdk/issues?q=is%3Aissue) and review the
[KNOWN_ISSUES file](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/KNOWN_ISSUES.md) to verify that your issue hasn't been reported yet.
Please consult the [security policy](https://github.com/IBM/cloudant-python-sdk/security/policy) before opening security related issues.
## Versioning and LTS support
This SDK follows semantic versioning with respect to the definition of user facing APIs.
This means under some circumstances breaking changes may occur within a major or minor version
of the SDK related to changes in supported language platforms.
The SDK is supported on the available LTS releases of the language platform.
The LTS language versions are listed in the prerequisites:
* [LTS versions currently supported by the SDK](https://github.com/IBM/cloudant-python-sdk/#prerequisites)
* [LTS versions for this release of the SDK](#prerequisites)
Incompatible changes from new language versions are not added to the SDK
until they are available in the minimum supported language version.
When language LTS versions move out of support the following will happen:
* Existing SDK releases will continue to run on obsolete language versions, but will no longer be supported.
* The minimum language version supported by the SDK will be updated to the next available LTS.
* New language features may be added in subsequent SDK releases that will cause breaking changes
if the new releases of the SDK are used with older, now unsupported, language levels.
## Open source at IBM
Find more open source projects on the [IBM GitHub](http://ibm.github.io/) page.
## Contributing
For more information, see [CONTRIBUTING](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/CONTRIBUTING.md).
## License
This SDK is released under the Apache 2.0 license. To read the full text of the license, see [LICENSE](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/LICENSE).
Raw data
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"author_email": "IBM <cldtsdks@us.ibm.com>",
"download_url": "https://files.pythonhosted.org/packages/0a/27/b065bc081711b82747a1a1e567c11b21168a1ede5c9e311c6aeb265ccb4c/ibmcloudant-0.9.3.tar.gz",
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"description": "[](https://github.com/IBM/cloudant-python-sdk/actions/workflows/test.yml)\n[](https://github.com/IBM/cloudant-python-sdk/releases/latest)\n[](https://ibm.github.io/cloudant-python-sdk/)\n\n# IBM Cloudant Python SDK Version 0.9.3\n\nIBM Cloudant Python SDK is a client library that interacts with the\n[IBM Cloudant APIs](https://cloud.ibm.com/apidocs/cloudant?code=python).\n\nDisclaimer: This library is still a 0.x release. We do consider this\nlibrary production-ready and capable, but there are still some\nlimitations we\u2019re working to resolve, and refinements we want to\ndeliver. We are working really hard to minimise the disruption from\nnow until the 1.0 release, but there may still be some changes that\nimpact applications using this SDK. For now, be sure to pin versions\nto avoid surprises.\n\n<details>\n<summary>Table of Contents</summary>\n\n<!-- toc -->\n- [Overview](#overview)\n- [Features](#features)\n- [Prerequisites](#prerequisites)\n- [Installation](#installation)\n- [Using the SDK](#using-the-sdk)\n * [Authentication](#authentication)\n + [Authentication with environment variables](#authentication-with-environment-variables)\n - [IAM API key authentication](#iam-api-key-authentication)\n - [IAM Trusted profile (container) authentication](#iam-trusted-profile-container-authentication)\n - [IAM Trusted profile (VPC) authentication](#iam-trusted-profile-vpc-authentication)\n - [Session cookie authentication](#session-cookie-authentication)\n + [Authentication with external configuration](#authentication-with-external-configuration)\n + [Programmatic authentication](#programmatic-authentication)\n * [Automatic retries](#automatic-retries)\n * [Request timeout configuration](#request-timeout-configuration)\n * [Code examples](#code-examples)\n + [1. Create a database and add a document](#1-create-a-database-and-add-a-document)\n + [2. Retrieve information from an existing database](#2-retrieve-information-from-an-existing-database)\n + [3. Update your previously created document](#3-update-your-previously-created-document)\n + [4. Delete your previously created document](#4-delete-your-previously-created-document)\n + [Further code examples](#further-code-examples)\n * [Error handling](#error-handling)\n * [Raw IO](#raw-io)\n * [Model classes vs dictionaries](#model-classes-vs-dictionaries)\n * [Further resources](#further-resources)\n * [Changes feed follower (beta)](#changes-feed-follower-beta)\n + [Introduction](#introduction)\n + [Modes of operation](#modes-of-operation)\n + [Configuring the changes follower](#configuring-the-changes-follower)\n + [Error suppression](#error-suppression)\n + [Follower operation](#follower-operation)\n + [Checkpointing](#checkpointing)\n + [Code examples](#code-examples-1)\n - [Initializing a changes follower](#initializing-a-changes-follower)\n - [Starting the changes follower](#starting-the-changes-follower)\n * [Start mode for continuous listening](#start-mode-for-continuous-listening)\n * [Start mode for one-off fetching](#start-mode-for-one-off-fetching)\n - [Processing changes](#processing-changes)\n * [Process continuous changes](#process-continuous-changes)\n * [Process one-off changes](#process-one-off-changes)\n - [Stopping the changes follower](#stopping-the-changes-follower)\n- [Questions](#questions)\n- [Issues](#issues)\n- [Versioning and LTS support](#versioning-and-lts-support)\n- [Open source at IBM](#open-source-at-ibm)\n- [Contributing](#contributing)\n- [License](#license)\n\n</details>\n\n## Overview\n\nThe IBM Cloudant Python SDK allows developers to programmatically\ninteract with [IBM Cloudant](https://cloud.ibm.com/apidocs/cloudant)\nwith the help of the `ibmcloudant` package.\n\n## Features\n\nThe purpose of this Python SDK is to wrap most of the HTTP request APIs\nprovided by Cloudant and supply other functions to ease the usage of Cloudant.\nThis SDK should make life easier for programmers to do what\u2019s really important\nto them: developing software.\n\nReasons why you should consider using Cloudant Python SDK in your\nproject:\n\n- Supported by IBM Cloudant.\n- Server compatibility with:\n - IBM Cloudant.\n - [Apache CouchDB 3.x](https://docs.couchdb.org/en/stable/) for data operations.\n- Includes all the most popular and latest supported endpoints for\n applications.\n- Handles the authentication.\n- Familiar user experience with IBM Cloud SDKs.\n- Flexibility to use either built-in models or byte-based requests and responses for documents.\n- Built-in [Changes feed follower](#changes-feed-follower-beta) (beta)\n- Instances of the client are unconditionally thread-safe.\n\n## Prerequisites\n\n- A\n [Cloudant](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-getting-started-with-cloudant)\n service instance or a\n [CouchDB](https://docs.couchdb.org/en/latest/install/index.html)\n server.\n- Python 3.9 or above.\n\n## Installation\n\nTo install, use `pip` or `easy_install`:\n\n```bash\npip install --upgrade \"ibmcloudant>=0.9.3\"\n```\n\nor\n\n```bash\neasy_install --upgrade \"ibmcloudant>=0.9.3\"\n```\n\n## Using the SDK\n\nFor fundamental SDK usage information and config options, please see the common [IBM Cloud SDK](https://github.com/IBM/ibm-cloud-sdk-common/blob/main/README.md) documentation.\n\nThis library requires configuration with a service URL and\n[Cloudant service credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-locating-your-service-credentials) to authenticate with your\naccount.\n\nThere are several ways to **set** these authentication properties:\n\n1. As [environment variables](#authentication-with-environment-variables)\n2. The [programmatic approach](#programmatic-authentication)\n3. With an [external credentials file](#authentication-with-external-configuration)\n\nThe following section describes the different authentication types and provides environment variable examples.\nExamples for other configuration methods are available by following the provided links.\n\n### Authentication\n\n\nThis library requires credentials to authenticate with IBM Cloudant. These credentials may be:\n* IBM Cloud IAM credentials (can be used with authentication types `CONTAINER`, `VPC` and `IAM`)\n * [IBM Cloud account](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-managing-access-for-cloudant#introduction-iam-ai) user, service ID or trusted profile credentials\n that have been granted access to the IBM Cloud Cloudant resource instance.\n * [IBM Cloudant service credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-locating-your-service-credentials) generated by the IBM Cloud Cloudant resource instance.\n* Username and password credentials (can be used with authentication types `COUCHDB_SESSION` and `BASIC`)\n * [IBM Cloudant service credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-locating-your-service-credentials) generated for an IBM Cloud Cloudant resource instance not configured as `IAM only`.\n * IBM Cloudant [legacy credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-work-with-your-account#basic-authentication) (i.e. username and password) for instances not in IBM Cloud.\n * IBM Cloudant [legacy API keys](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-work-with-your-account#api-keys).\n\nFor other compatible APIs that are not Cloudant accounts (e.g. Apache CouchDB) non-IAM based authentication types\nmust be used.\n\nThis table summarizes the available authentication types.\nThe authentication types are listed in order of recommendation, preferably use the authentication type\nfrom the first row in the table that is compatible with your environment.\n\n| Authentication type | Recommended for | `AUTH_TYPE` | Description |\n| --- | --- | --- | --- |\n| IAM Trusted Profiles compute resource ([container](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#container-authentication)) | Cloudant<BR>(SDK running in IBM Cloud IKS) | `CONTAINER` | Obtains a compute resource (CR) token from the container.<BR>Exchanges the CR token for an IAM `access_token`.<BR>Adds an `Authorization: Bearer <access_token>` header to each HTTP request.<BR>Automatically renews the access token when needed. |\n| IAM Trusted Profiles compute resource ([VPC](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#vpc-instance-authentication)) | Cloudant<BR>(SDK running in IBM Cloud VPC) | `VPC` | Obtains an identity token from the VPC instance metadata.<BR>Exchanges the identity token for an IAM `access_token`.<BR>Adds an `Authorization: Bearer <access_token>` header to each HTTP request.<BR>Automatically renews the access token when needed. |\n| [IAM API key](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#identity-and-access-management-iam-authentication) | Cloudant | `IAM` | Exchanges an IAM API key for an IAM `access_token`.<BR>Adds an `Authorization: Bearer <access_token>` header to each HTTP request.<BR>Automatically renews the access token when needed. |\n| [Session cookie](#session-cookie-authentication) | [Cloudant](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-work-with-your-account#cookie-authentication)<BR>(legacy credentials & instances without IAM)<BR><BR>[Apache CouchDB](https://docs.couchdb.org/en/stable/api/server/authn.html#cookie-authentication) | `COUCHDB_SESSION` | Exchanges credentials with `/_session` endpoint to retrieve a cookie.<BR>Adds `Cookie` header and content to each HTTP request.<BR>Automatically renews session when needed. |\n| [Bearer token](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#bearer-token-authentication) | [Apache CouchDB](https://docs.couchdb.org/en/stable/api/server/authn.html#jwt-authentication)<BR>(using JWT authentication) | `BEARERTOKEN` | Adds an `Authorization: Bearer <token>` to each HTTP request.<BR>No token management or renewal.<BR>Also compatible with IAM access tokens managed independently of the SDK. |\n| [Basic](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#basic-authentication) | [Apache CouchDB](https://docs.couchdb.org/en/stable/api/server/authn.html#basic-authentication)<BR>(if cookies are not enabled) | `BASIC` | Adds an `Authorization: Basic <encoded username and password>` header to each HTTP request. |\n| [None](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md#no-auth-authentication) | - | `NOAUTH` | Note that this authentication type only works for operations against a database allowing access for unauthenticated users. |\n\nThe default authentication type for the SDK is `CONTAINER` unless `APIKEY` configuration is supplied, which changes the default authentication type to `IAM`.\n\n#### Authentication with environment variables\n\nThe default service name is `CLOUDANT` so `CLOUDANT_` prefixed names are used in these examples.\n\nAny custom service name prefix can be used as long as the matching name is used to instantiate the SDK client\nand the same prefix is used for all configuration options.\n\n##### IAM API key authentication\n\nFor Cloudant *IAM API key authentication*, set the following environmental variables by\nreplacing the `<url>` and `<apikey>` with your proper\n[service credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-locating-your-service-credentials). There is no need to set\n`CLOUDANT_AUTH_TYPE` to `IAM` because it is the default when an `APIKEY` is set.\n\n```bash\nCLOUDANT_URL=<url>\nCLOUDANT_APIKEY=<apikey>\n```\n\n##### IAM Trusted profile (container) authentication\n\nFor Cloudant *IAM Trusted profile compute resource container authentication*, set the following environmental variables by\nreplacing the `<url>` and `<id>` with your values. There is no need to set\n`CLOUDANT_AUTH_TYPE` to `CONTAINER` because it is the default.\n\n```bash\nCLOUDANT_URL=<url>\nCLOUDANT_IAM_PROFILE_ID=<id>\n```\n\nAlternatively a profile name may be used instead of an ID by replacing `CLOUDANT_IAM_PROFILE_ID` with `CLOUDANT_IAM_PROFILE_NAME`.\n\n##### IAM Trusted profile (VPC) authentication\n\nFor Cloudant *IAM Trusted profile compute resource vpc authentication*, set the following environmental variables by\nreplacing the `<url>` and `<id>` with your values.\n\n```bash\nCLOUDANT_AUTH_TYPE=VPC\nCLOUDANT_URL=<url>\nCLOUDANT_IAM_PROFILE_ID=<id>\n```\n\nAlternatively a profile CRN may be used instead of an ID by replacing `CLOUDANT_IAM_PROFILE_ID` with `CLOUDANT_IAM_PROFILE_CRN`.\n\n##### Session cookie authentication\n\nFor `COUCHDB_SESSION` authentication, set the following environmental variables\nby replacing the `<url>`, `<username>` and `<password>` with your proper\n[service credentials](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-locating-your-service-credentials).\n\n```bash\nCLOUDANT_AUTH_TYPE=COUCHDB_SESSION\nCLOUDANT_URL=<url>\nCLOUDANT_USERNAME=<username>\nCLOUDANT_PASSWORD=<password>\n```\n\n#### Authentication with external configuration\n\nTo use an external configuration file, the\n[Cloudant API docs](https://cloud.ibm.com/apidocs/cloudant?code=python#authentication-with-external-configuration),\nor the\n[general SDK usage information](https://github.com/IBM/ibm-cloud-sdk-common#using-external-configuration)\nwill guide you.\n\n#### Programmatic authentication\n\nTo learn more about how to use programmatic authentication, see the related\ndocumentation in the\n[Cloudant API docs](https://cloud.ibm.com/apidocs/cloudant?code=python#programmatic-authentication)\nor in the\n[Python SDK Core document](https://github.com/IBM/python-sdk-core/blob/main/Authentication.md) about authentication.\n\n### Automatic retries\n\nThe SDK supports a generalized retry feature that can automatically retry on common errors.\n\nThe [automatic retries](https://github.com/IBM/ibm-cloud-sdk-common#automatic-retries) section has details on how to enable the retries with default values and customize the retries programmatically or with external configuration.\n\n### Request timeout configuration\n\nNo request timeout is defined, but a 2.5m read and a 60s connect timeout are set by default. Be sure to set a request timeout appropriate to your application usage and environment.\nThe [request timeout](https://github.com/IBM/ibm-cloud-sdk-common#configuring-request-timeouts) section contains details on how to change the value.\n\n**Note:** System settings may take precedence over configured timeout values.\n\n### Code examples\n\nThe following code examples\n[authenticate with the environment variables](#authentication-with-environment-variables).\n\n#### 1. Create a database and add a document\n\n**Note:** This example code assumes that `orders` database does not exist in your account.\n\nThis example code creates `orders` database and adds a new document \"example\"\ninto it. To connect, you must set your environment variables with\nthe *service url*, *authentication type* and *authentication credentials*\nof your Cloudant service.\n\nCloudant environment variable naming starts with a *service name* prefix that identifies your service.\nBy default, this is `CLOUDANT`, see the settings in the\n[authentication with environment variables section](#authentication-with-environment-variables).\n\nIf you would like to rename your Cloudant service from `CLOUDANT`,\nyou must use your defined service name as the prefix for all Cloudant related environment variables.\n\nOnce the environment variables are set, you can try out the code examples.\n\n```py\nfrom ibm_cloud_sdk_core import ApiException\nfrom ibmcloudant.cloudant_v1 import CloudantV1, Document\n\n# 1. Create a client with `CLOUDANT` default service name =============\nclient = CloudantV1.new_instance()\n\n# 2. Create a database ================================================\nexample_db_name = \"orders\"\n\n# Try to create database if it doesn't exist\ntry:\n put_database_result = client.put_database(\n db=example_db_name\n ).get_result()\n if put_database_result[\"ok\"]:\n print(f'\"{example_db_name}\" database created.')\nexcept ApiException as ae:\n if ae.status_code == 412:\n print(f'Cannot create \"{example_db_name}\" database, ' +\n 'it already exists.')\n\n# 3. Create a document ================================================\n# Create a document object with \"example\" id\nexample_doc_id = \"example\"\n# Setting `id` for the document is optional when \"post_document\"\n# function is used for CREATE. When `id` is not provided the server\n# will generate one for your document.\nexample_document: Document = Document(id=example_doc_id)\n\n# Add \"name\" and \"joined\" fields to the document\nexample_document.name = \"Bob Smith\"\nexample_document.joined = \"2019-01-24T10:42:59.000Z\"\n\n# Save the document in the database with \"post_document\" function\ncreate_document_response = client.post_document(\n db=example_db_name,\n document=example_document\n).get_result()\n\n# =====================================================================\n# Note: saving the document can also be done with the \"put_document\"\n# function. In this case `doc_id` is required for a CREATE operation:\n\"\"\"\ncreate_document_response = client.put_document(\n db=example_db_name,\n doc_id=example_doc_id,\n document=example_document\n).get_result()\n\"\"\"\n# =====================================================================\n\n# Keeping track of the revision number of the document object\n# is necessary for further UPDATE/DELETE operations:\nexample_document.rev = create_document_response[\"rev\"]\nprint(f'You have created the document:\\n{example_document}')\n```\n\nWhen you run the code, you see a result similar to the following output.\n\n```text\n\"orders\" database created.\nYou have created the document:\n{\n \"_id\": \"example\",\n \"_rev\": \"1-1b403633540686aa32d013fda9041a5d\",\n \"name\": \"Bob Smith\",\n \"joined\": \"2019-01-24T10:42:99.000Z\"\n}\n```\n\n#### 2. Retrieve information from an existing database\n\n**Note**: This example code assumes that you have created both the `orders`\ndatabase and the `example` document by\n[running the previous example code](#1-create-a-database-and-add-a-document)\nsuccessfully. Otherwise, the following error message occurs, \"Cannot delete document because either 'orders'\ndatabase or 'example' document was not found.\"\n\n<details>\n<summary>Gather database information example</summary>\n\n```py\nimport json\n\nfrom ibmcloudant.cloudant_v1 import CloudantV1\n\n# 1. Create a client with `CLOUDANT` default service name ============\nclient = CloudantV1.new_instance()\n\n# 2. Get server information ===========================================\nserver_information = client.get_server_information(\n).get_result()\n\nprint(f'Server Version: {server_information[\"version\"]}')\n\n# 3. Get database information for \"orders\" ==========================\ndb_name = \"orders\"\n\ndb_information = client.get_database_information(\n db=db_name\n).get_result()\n\n# 4. Show document count in database ==================================\ndocument_count = db_information[\"doc_count\"]\n\nprint(f'Document count in \\\"{db_information[\"db_name\"]}\\\" '\n f'database is {document_count}.')\n\n# 5. Get \"example\" document out of the database by document id ============\ndocument_example = client.get_document(\n db=db_name,\n doc_id=\"example\"\n).get_result()\n\nprint(f'Document retrieved from database:\\n'\n f'{json.dumps(document_example, indent=2)}')\n```\n\n</details>\nWhen you run the code, you see a result similar to the following output.\n\n```text\nServer Version: 2.1.1\nDocument count in \"orders\" database is 1.\nDocument retrieved from database:\n{\n \"_id\": \"example\",\n \"_rev\": \"1-1b403633540686aa32d013fda9041a5d\",\n \"name\": \"Bob Smith\",\n \"joined\": \"2019-01-24T10:42:99.000Z\"\n}\n```\n\n#### 3. Update your previously created document\n\n**Note**: This example code assumes that you have created both the `orders`\ndatabase and the `example` document by\n[running the previous example code](#1-create-a-database-and-add-a-document)\nsuccessfully. Otherwise, the following error message occurs, \"Cannot update document because either 'orders'\ndatabase or 'example' document was not found.\"\n\n<details>\n<summary>Update code example</summary>\n\n```py\nimport json\n\nfrom ibm_cloud_sdk_core import ApiException\nfrom ibmcloudant.cloudant_v1 import CloudantV1\n\n# 1. Create a client with `CLOUDANT` default service name =============\nclient = CloudantV1.new_instance()\n\n# 2. Update the document ==============================================\nexample_db_name = \"orders\"\nexample_doc_id = \"example\"\n\n# Try to get the document if it previously existed in the database\ntry:\n document = client.get_document(\n db=example_db_name,\n doc_id=example_doc_id\n ).get_result()\n\n # =================================================================\n # Note: for response byte stream use:\n \"\"\"\n document_as_byte_stream = client.get_document_as_stream(\n db=example_db_name,\n doc_id=example_doc_id\n ).get_result()\n \"\"\"\n # =================================================================\n\n # Add Bob Smith's address to the document\n document[\"address\"] = \"19 Front Street, Darlington, DL5 1TY\"\n\n # Remove the joined property from document object\n if \"joined\" in document:\n document.pop(\"joined\")\n\n # Update the document in the database\n update_document_response = client.post_document(\n db=example_db_name,\n document=document\n ).get_result()\n\n # =================================================================\n # Note 1: for request byte stream use:\n \"\"\"\n update_document_response = client.post_document(\n db=example_db_name,\n document=document_as_byte_stream\n ).get_result()\n \"\"\"\n # =================================================================\n\n # =================================================================\n # Note 2: updating the document can also be done with the\n # \"put_document\" function. `doc_id` and `rev` are required for an\n # UPDATE operation, but `rev` can be provided in the document\n # object as `_rev` too:\n \"\"\"\n update_document_response = client.put_document(\n db=example_db_name,\n doc_id=example_doc_id, # doc_id is a required parameter\n rev=document[\"_rev\"],\n document=document # _rev in the document object CAN replace above `rev` parameter\n ).get_result()\n \"\"\"\n # =================================================================\n\n # Keeping track of the latest revision number of the document\n # object is necessary for further UPDATE/DELETE operations:\n document[\"_rev\"] = update_document_response[\"rev\"]\n print(f'You have updated the document:\\n' +\n json.dumps(document, indent=2))\n\nexcept ApiException as ae:\n if ae.status_code == 404:\n print('Cannot delete document because either ' +\n f'\"{example_db_name}\" database or \"{example_doc_id}\" ' +\n 'document was not found.')\n```\n\n</details>\nWhen you run the code, you see a result similar to the following output.\n\n```text\n{\n \"_id\": \"example\",\n \"_rev\": \"2-4e2178e85cffb32d38ba4e451f6ca376\",\n \"name\": \"Bob Smith\",\n \"address\": \"19 Front Street, Darlington, DL5 1TY\"\n}\n```\n\n#### 4. Delete your previously created document\n\n**Note**: This example code assumes that you have created both the `orders`\ndatabase and the `example` document by\n[running the previous example code](#1-create-a-database-and-add-a-document)\nsuccessfully. Otherwise, the following error message occurs, \"Cannot delete document because either 'orders'\ndatabase or 'example' document was not found.\"\n\n<details>\n<summary>Delete code example</summary>\n\n```py\nfrom ibm_cloud_sdk_core import ApiException\nfrom ibmcloudant.cloudant_v1 import CloudantV1\n\n# 1. Create a client with `CLOUDANT` default service name =============\nclient = CloudantV1.new_instance()\n\n# 2. Delete the document ==============================================\nexample_db_name = \"orders\"\nexample_doc_id = \"example\"\n\n# Try to get the document if it previously existed in the database\ntry:\n document = client.get_document(\n db=example_db_name,\n doc_id=example_doc_id\n ).get_result()\n\n delete_document_response = client.delete_document(\n db=example_db_name,\n doc_id=example_doc_id, # `doc_id` is required for DELETE\n rev=document[\"_rev\"] # `rev` is required for DELETE\n ).get_result()\n\n if delete_document_response[\"ok\"]:\n print('You have deleted the document.')\n\nexcept ApiException as ae:\n if ae.status_code == 404:\n print('Cannot delete document because either ' +\n f'\"{example_db_name}\" database or \"{example_doc_id}\"' +\n 'document was not found.')\n```\n\n</details>\nWhen you run the code, you see the following output.\n\n```text\nYou have deleted the document.\n```\n\n#### Further code examples\n\nFor a complete list of code examples, see the [examples directory](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/examples#examples-for-python).\n\n### Error handling\n\nFor sample code on handling errors, see\n[Cloudant API docs](https://cloud.ibm.com/apidocs/cloudant?code=python#error-handling).\n\n### Raw IO\n\nFor endpoints that read or write document content it is possible to bypass\nusage of the built-in object with byte streams.\n\nDepending on the specific SDK operation it may be possible to:\n* accept a user-provided byte stream to send to the server as a request body\n* return a byte stream of the server response body to the user\n\nRequest byte stream can be supplied for arguments that accept the `BinaryIO` type.\nFor these cases you can pass this byte stream directly to the HTTP request body.\n\nResponse byte stream is supported in functions with the suffix of `_as_stream`.\nThe returned byte stream allows the response body to be consumed\nwithout triggering JSON unmarshalling that is typically performed by the SDK.\n\nThe [update document](#3-update-your-previously-created-document) section\ncontains examples for both request and response byte stream cases.\n\nThe API reference contains further examples of using byte streams.\nThey are titled \"Example request as stream\" and are initially collapsed.\nExpand them to see examples of:\n\n- Byte requests:\n - [Bulk modify multiple documents in a database](https://cloud.ibm.com/apidocs/cloudant?code=python#postbulkdocs)\n\n- Byte responses:\n - [Query a list of all documents in a database](https://cloud.ibm.com/apidocs/cloudant?code=python#postalldocs)\n - [Query the database document changes feed](https://cloud.ibm.com/apidocs/cloudant?code=python#postchanges)\n\n### Model classes vs dictionaries\n\nThis SDK supports two possible formats to define an HTTP request. One approach uses only model classes and the other only dictionaries.\n\n<details>\n<summary>Example using model class structure</summary>\n\n```py\nfrom ibmcloudant.cloudant_v1 import DesignDocument, CloudantV1, DesignDocumentOptions, SearchIndexDefinition\n\nclient = CloudantV1.new_instance()\n\nprice_index = SearchIndexDefinition(\n index='function (doc) { index(\"price\", doc.price); }'\n)\n\ndesign_document_options = DesignDocumentOptions(\n partitioned=True\n)\n\npartitioned_design_doc = DesignDocument(\n indexes={'findByPrice': price_index},\n options=design_document_options\n)\n\nresponse = client.put_design_document(\n db='products',\n design_document=partitioned_design_doc,\n ddoc='appliances'\n).get_result()\n\nprint(response)\n```\n\n</details>\n\n<details>\n<summary>Same example using dictionary structure</summary>\n\n```py\nfrom ibmcloudant.cloudant_v1 import CloudantV1\n\nclient = CloudantV1.new_instance()\n\nprice_index = {\n 'index': 'function (doc) { index(\"price\", doc.price); }'\n}\n\npartitioned_design_doc = {\n 'indexes': {'findByPrice': price_index},\n 'options': {'partitioned': True},\n}\n\nresponse = client.put_design_document(\n db='products',\n design_document=partitioned_design_doc,\n ddoc='appliances'\n).get_result()\n\nprint(response)\n```\n\n</details>\n\nSince model classes and dicts are different data structures, they cannot be combined.\n\n<details>\n<summary>This solution will be invalid</summary>\n\n```py\nfrom ibmcloudant.cloudant_v1 import CloudantV1, DesignDocument\n\nclient = CloudantV1.new_instance()\n\nprice_index = {\n 'index': 'function (doc) { index(\"price\", doc.price); }'\n}\n\npartitioned_design_doc = DesignDocument(\n indexes={'findByPrice': price_index},\n options={'partitioned': True}\n)\n\nresponse = client.put_design_document(\n db='products',\n design_document=partitioned_design_doc,\n ddoc='appliances'\n).get_result()\n\nprint(response)\n```\n\n</details>\n\n### Further resources\n\n- [Cloudant API docs](https://cloud.ibm.com/apidocs/cloudant?code=python):\n API reference including usage examples for Cloudant Python SDK API.\n- [Pydoc](https://ibm.github.io/cloudant-python-sdk/):\n Cloudant Python SDK API Documentation.\n- [Cloudant docs](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-getting-started-with-cloudant):\n The official documentation page for Cloudant.\n- [Cloudant blog](https://blog.cloudant.com/):\n Many useful articles about how to optimize Cloudant for common problems.\n\n### Changes feed follower (beta)\n\n#### Introduction\n\nThe SDK provides a changes feed follower utility (currently beta).\nThis helper utility connects to the `_changes` endpoint and returns the individual change items.\nIt removes some of the complexity of using the `_changes` endpoint by setting some options automatically\nand providing error suppression and retries.\n\n*Tip: the changes feed often does not meet user expectations or assumptions.*\n\nConsult the [Cloudant changes feed FAQ](https://cloud.ibm.com/docs/Cloudant?topic=Cloudant-faq-using-changes-feed)\nto get a better understanding of the limitations and suitable use-cases before using the changes feed in your application.\n\n#### Modes of operation\n\nThere are two modes of operation:\n* Start mode\n * Fetches the changes from the supplied `since` sequence (by default the feed will start from `now`).\n * Fetches all available changes and then continues listening for new changes indefinitely unless encountering an end condition.\n * An example use case for this mode is event driven workloads.\n* Start one-off mode\n * Fetches the changes from the supplied `since` sequence (by default the feed will start from the beginning).\n * Fetches all available changes and then stops when either there are no further changes pending or encountering an end condition.\n * An example use case for this mode is ETL style workloads.\n\n#### Configuring the changes follower\n\nThe SDK's model of changes feed options is also used to configure the follower.\nHowever, a subset of the options are invalid as they are configured internally by the implementation.\nSupplying these options when instantiating the follower causes an error.\nThe invalid options are:\n* `descending`\n* `feed`\n* `heartbeat`\n* `lastEventId` - use `since` instead\n* `timeout`\n* Only the value of `_selector` is permitted for the `filter` option. This restriction is because selector\n based filters perform better than JavaScript backed filters. Configuring a non-selector based filter will\n cause the follower to error.\n\nNote that the `limit` parameter will terminate the follower at the given number of changes in either\noperating mode.\n\nThe changes follower requires the client to have HTTP timeouts of at least 1 minute and will error during\ninstantiation if it is insufficient. The default client configuration has sufficiently long timeouts.\n\nFor use-cases where these configuration limitations are deemed too restrictive then it is recommended to\nwrite code to use the SDK's [POST `_changes` API](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/examples#postchanges) instead of the follower.\n\n#### Error suppression\n\nBy default, the changes follower will suppress transient errors indefinitely and attempt to run to completion or listen forever as\ndictated by the operating mode.\nFor applications where that is not desirable an optional error tolerance duration may be specified to control the time since\nthe last successful response that transient errors will be suppressed. This can be used, for example, by applications as a grace period\nbefore reporting an error and requiring intervention.\n\nThere are some additional points to consider for error suppression:\n* Errors considered terminal, for example, the database not existing or invalid credentials are never suppressed and will error immediately.\n* The error suppression duration is not guaranteed to fire immediately after lapsing and should be considered a minimum suppression time.\n* The changes follower will back-off between retries and as such may remain paused for a short while after the transient errors have resolved.\n* If the underlying SDK client used to initialize the follower also has retries configured then errors could be suppressed for significantly\n longer than the follower's configured error tolerance duration depending on the configuration options.\n\n#### Follower operation\n\nFor both modes:\n* The end conditions are:\n * A terminal error (HTTP codes `400`, `401`, `403` `404`).\n * Transient errors occur for longer than the error tolerance duration. Transient errors are all other HTTP status codes and connection errors.\n * The number of changes received reaches the configured `limit`.\n * The feed is terminated early by calling stop.\n\nAs is true for the `_changes` endpoint change items have *at least once* delivery and an individual item\nmay be received multiple times. When using the follower change items may be repeated even within a limited\nnumber of changes (i.e. using the `limit` option) this is a minor difference from using `limit` on the HTTP native API.\n\nThe follower is not optimized for some use cases and it is not recommended to use it in cases where:\n* Setting `include_docs` and larger document sizes (for example > 10 kiB).\n* The volume of changes is very high (if the rate of changes in the database exceeds the follower's rate of pulling them it will never catch-up).\n\nIn these cases use-case specific control over the number of change requests made and the content size of the responses\nmay be achieved by using the SDK's [POST `_changes` API](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/examples#postchanges).\n\n#### Checkpointing\n\nThe changes follower does not checkpoint since it has no information about whether a change item has been\nprocessed by the consuming application after being received. It is the application developer's responsibility\nto store the sequence IDs to have appropriate checkpoints and to re-initialize the follower with the required\n`since` value after, for example, the application restarts.\n\nThe frequency and conditions for checkpointing are application specific and some applications may be tolerant\nof dropped changes. This section is intended only to provide general guidance on how to avoid missing changes.\n\nTo guarantee processing of all changes the sequence ID from a change item must not be persisted until *after*\nthe processing of the change item by the application has completed. As indicated previously change items are\ndelivered *at least once* so application code must be able to handle repeated changes already and it is\npreferable to restart from an older `since` value and receive changes again than risk missing them.\n\nThe sequence IDs are available on each change item by default, but may be omitted from some change items when\nusing the `seq_interval` configuration option. Infrequent sequence IDs may improve performance by reducing\nthe amount of data that needs to be transferred, but the trade-off is that more changes will be repeated if\nit is necessary to resume the changes follower.\n\nExtreme care should be taken with persisting sequences if choosing to process change items in parallel as there\nis a considerable risk of missing changes on a restart if the sequence is recorded out of order.\n\n#### Code examples\n\n##### Initializing a changes follower\n```py\nimport ChangesFollower\nfrom ibmcloudant.cloudant_v1 import CloudantV1\n\nclient = CloudantV1.new_instance()\n\ncf_params = {\n 'db': 'example', # Required: the database name.\n 'limit': 100, # Optional: return only 100 changes (including duplicates).\n 'since': '3-g1AG3...' # Optional: start from this sequence ID (e.g. with a value read from persistent storage).\n}\n\nchanges_follower = ChangesFollower(\n service=client, # Required: the Cloudant service client instance.\n error_tolerance=10000, # Optional: suppress transient errors for at least 10 seconds before terminating.\n **cf_params # Required: changes feed configuration options dict.\n)\n```\n\n##### Starting the changes follower\n\n###### Start mode for continuous listening\n```py\nimport Iterable\n\nfrom ibmcloudant import ChangesFollower\nfrom ibmcloudant.cloudant_v1 import CloudantV1, ChangesResultItem\n\nclient = CloudantV1.new_instance()\n\nchanges_follower = ChangesFollower(\n service=client,\n **{'db': 'example'})\n\nchanges_items: Iterable[ChangesResultItem] = changes_follower.start()\n# Note: iterable will not do anything until it is iterated\n# Create a for loop to iterate over the flow of changes\n# for changes_item in changes_items: ...\n```\n\n###### Start mode for one-off fetching\n```py\nimport Iterable\n\nfrom ibmcloudant import ChangesFollower\nfrom ibmcloudant.cloudant_v1 import CloudantV1, ChangesResultItem\n\nclient = CloudantV1.new_instance()\n\nchanges_follower = ChangesFollower(\n service=client,\n **{'db': 'example'})\n\nchanges_items: Iterable[ChangesResultItem] = changes_follower.start_one_off()\n# Note: iterable will not do anything until it is iterated\n# Create a for loop to iterate over the flow of changes\n# for changes_item in changes_items: ...\n```\n\n##### Processing changes\n\n###### Process continuous changes\n```py\nimport ChangesFollower\nfrom ibmcloudant.cloudant_v1 import CloudantV1\n\nclient = CloudantV1.new_instance()\n\n# Start from a previously persisted seq\n# Normally this would be read by the app from persistent storage\n# e.g. previously_persisted_seq = your_app_persistence_read_func()\npreviously_persisted_seq = '3-g1AG3...'\nchanges_follower = ChangesFollower(\n service=client,\n **{'db': 'example', 'since': previously_persisted_seq})\n\nchanges_items = changes_follower.start()\nfor changes_item in changes_items:\n # do something with changes\n print(changes_item.id)\n for change in changes_item.changes:\n print(change.rev)\n # when change item processing is complete app can store seq\n seq = changes_item.seq\n # write seq to persistent storage for use as since if required to resume later\n # e.g. your_app_persistence_write_func(seq)\n # keep processing changes until the application is terminated or some other stop condition is reached\n\n# Note: iterator above is blocking, code here will be unreachable\n# until the iteration is stopped or another stop condition is reached.\n# For long running followers careful consideration should be made of where to call stop on the iterator.\n```\n\n###### Process one-off changes\n```py\nimport ChangesFollower\nfrom ibmcloudant.cloudant_v1 import CloudantV1\n\nclient = CloudantV1.new_instance()\n\n# Start from a previously persisted seq\n# Normally this would be read by the app from persistent storage\n# e.g. previously_persisted_seq = your_app_persistence_read_func()\npreviously_persisted_seq = '3-g1AG3...'\nchanges_follower = ChangesFollower(\n service=client,\n **{'db': 'example', 'since': previously_persisted_seq})\n\nchanges_items = changes_follower.start_one_off()\nfor changes_item in changes_items:\n # do something with changes\n print(changes_item.id)\n for change in changes_item.changes:\n print(change.rev)\n # when change item processing is complete app can store seq\n seq = changes_item.seq\n # write seq to persistent storage for use as since if required to resume later\n # e.g. your_app_persistence_write_func(seq)\n\n# Note: iterator above is blocking, code here will be unreachable\n# until all changes are processed (or another stop condition is reached).\n```\n\n##### Stopping the changes follower\n```py\nimport ChangesFollower\nfrom ibmcloudant.cloudant_v1 import CloudantV1\n\nclient = CloudantV1.new_instance()\nchanges_follower = ChangesFollower(\n service=client,\n **{'db': 'example'})\nchanges_items = changes_follower.start()\n\nfor changes_item in changes_items:\n # Option 1: call stop after some condition\n # Note that since the iterator is blocking at least one item\n # must be returned from it to reach to this point.\n # Additional changes may be processed before the iterator stops.\n changes_follower.stop()\n\n# Option 2: call stop method when you want to end the continuous loop from\n# outside the iterator. For example, you've put the changes follower in a\n# separate thread and need to call stop on the main thread.\n# Note: in this context the call must be made from a different thread because\n# code immediately following the iterator is unreachable until the iterator\n# has stopped.\nchanges_follower.stop()\n```\n\n## Questions\n\nIf you are having difficulties using this SDK or have a question about the\nIBM Cloud services, ask a question on\n[Stack Overflow](http://stackoverflow.com/questions/ask?tags=ibm-cloud).\n\n## Issues\n\nIf you encounter an issue with the project, you are welcome to submit a\n[bug report](https://github.com/IBM/cloudant-python-sdk/issues).\n\nBefore you submit a bug report, search for\n[similar issues](https://github.com/IBM/cloudant-python-sdk/issues?q=is%3Aissue) and review the\n[KNOWN_ISSUES file](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/KNOWN_ISSUES.md) to verify that your issue hasn't been reported yet.\n\nPlease consult the [security policy](https://github.com/IBM/cloudant-python-sdk/security/policy) before opening security related issues.\n\n## Versioning and LTS support\n\nThis SDK follows semantic versioning with respect to the definition of user facing APIs.\nThis means under some circumstances breaking changes may occur within a major or minor version\nof the SDK related to changes in supported language platforms.\n\nThe SDK is supported on the available LTS releases of the language platform.\nThe LTS language versions are listed in the prerequisites:\n* [LTS versions currently supported by the SDK](https://github.com/IBM/cloudant-python-sdk/#prerequisites)\n* [LTS versions for this release of the SDK](#prerequisites)\n\nIncompatible changes from new language versions are not added to the SDK\nuntil they are available in the minimum supported language version.\n\nWhen language LTS versions move out of support the following will happen:\n* Existing SDK releases will continue to run on obsolete language versions, but will no longer be supported.\n* The minimum language version supported by the SDK will be updated to the next available LTS.\n* New language features may be added in subsequent SDK releases that will cause breaking changes\n if the new releases of the SDK are used with older, now unsupported, language levels.\n\n## Open source at IBM\n\nFind more open source projects on the [IBM GitHub](http://ibm.github.io/) page.\n\n## Contributing\n\nFor more information, see [CONTRIBUTING](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/CONTRIBUTING.md).\n\n## License\n\nThis SDK is released under the Apache 2.0 license. To read the full text of the license, see [LICENSE](https://github.com/IBM/cloudant-python-sdk/tree/v0.9.3/LICENSE).\n",
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