mypy-boto3-rds Type Annotations

Warnings

• breaking Python 3.8 support has been explicitly removed in `mypy-boto3-builder` version 8.12.0 and subsequent releases. Users on Python 3.8 or older will not receive updates or new stubs.
  Fix: Upgrade your Python environment to 3.9 or newer. The `requires_python` field is `>=3.9`.
• breaking Migration to PEP 561 compliant packages in `mypy-boto3-builder` 8.12.0. This might affect how type checkers locate stubs in complex environments or if you rely on older non-PEP 561 compliant patterns.
  Fix: Ensure your type checker (e.g., mypy, pyright) is up-to-date and configured to correctly resolve PEP 561 packages. Generally, this migration improves discoverability.
• breaking TypeDef naming conventions may change between major `mypy-boto3-builder` versions, leading to potential breaking changes if you directly import or refer to specific TypeDef names. For example, `CreateDistributionRequestRequestTypeDef` became `CreateDistributionRequestTypeDef`.
  Fix: Refer to the `mypy-boto3-builder` release notes and the specific service documentation for `mypy-boto3-rds` when upgrading to check for TypeDef name changes. Update your code to use the new names.
• gotcha When using `mypy-boto3` stubs with linters like Pylint, you might encounter 'undefined variable' errors if you directly import stub classes without a runtime equivalent. This often happens because stubs are only for type-checking and not available at runtime.
  Fix: Use a `from typing import TYPE_CHECKING` block. Inside this block, import the `mypy-boto3-rds` types. In the runtime path, assign `object` to these type aliases, e.g., `if TYPE_CHECKING: from mypy_boto3_rds.client import RDSClient else: RDSClient = object`.
• gotcha For optimal type checking, it is crucial to ensure that the version of `mypy-boto3-rds` (or `boto3-stubs`) installed matches or is compatible with the version of `boto3` you are using at runtime. Mismatched versions can lead to incorrect type hints or missing definitions.
  Fix: Always pin your `boto3` and `mypy-boto3-rds` (or `boto3-stubs`) versions in your `requirements.txt` or `pyproject.toml` to ensure consistency. For example: `boto3==1.x.y` and `boto3-stubs[rds]==1.x.y`.

Install

• pip install mypy-boto3-rds Standalone package for RDS
• pip install 'boto3-stubs[rds]' Recommended: Install as part of boto3-stubs

Imports

• RDSClient

  from mypy_boto3_rds.client import RDSClient

• DescribeDBInstancesMessageTypeDef

  from mypy_boto3_rds.type_defs import DescribeDBInstancesMessageTypeDef

  Example of importing a specific TypeDef.
• DescribeDBInstancesPaginator

  from mypy_boto3_rds.paginators import DescribeDBInstancesPaginator

  Example of importing a Paginator.

Quickstart

This quickstart demonstrates how to use `mypy-boto3-rds` for type-hinting a `boto3` RDS client. It shows explicit type annotation for the client, an API call with type-hinted response, and usage of a paginator. The `TYPE_CHECKING` block ensures that type-only imports do not affect runtime dependencies. Note that `boto3-stubs[rds]` is the idiomatic way to install type annotations for a specific service.

import boto3
from typing import TYPE_CHECKING

# It is generally recommended to install 'boto3-stubs[rds]' for full integration.
# For explicit type annotation of the client:
if TYPE_CHECKING:
    from mypy_boto3_rds.client import RDSClient
    from mypy_boto3_rds.type_defs import DescribeDBInstancesMessageTypeDef

    # Example of a Paginator
    from mypy_boto3_rds.paginators import DescribeDBInstancesPaginator


# Initialize boto3 client
# For better type inference, explicitly annotate the client if TYPE_CHECKING is True
client: RDSClient = boto3.client("rds") if TYPE_CHECKING else boto3.client("rds")

try:
    # Example API call with type-hinted response
    response = client.describe_db_instances(
        MaxRecords=20
    )
    # The 'response' object will have type hints based on DescribeDBInstancesMessageTypeDef
    print(f"Found {len(response.get('DBInstances', []))} DB instances.")

    # Example usage of a Paginator
    paginator: DescribeDBInstancesPaginator = client.get_paginator("describe_db_instances")
    for page in paginator.paginate():
        print(f"Processing page with {len(page.get('DBInstances', []))} instances.")

except Exception as e:
    print(f"An error occurred: {e}")