How can I generate OpenAPI schemas for type annotations in FastAPI?

How can I generate OpenAPI schemas automatically from type annotations in FastAPI, and what steps are involved in ensuring that the generated schemas are accurate and complete?

Install FastAPI: Start by installing FastAPI and any required dependencies.

Define Your API Endpoints: Use type annotations to define your API endpoints. FastAPI will use these annotations to understand and generate the OpenAPI schema.

Use Pydantic Models: Create models using Pydantic to define the structure of your data. These models will ensure that incoming data is validated and correctly represented in the OpenAPI schema.

Automatic Schema Generation: FastAPI automatically generates the OpenAPI schema based on the type annotations and Pydantic models you’ve defined. You can access this schema via the /openapi.json endpoint.

Customize the OpenAPI Schema: If necessary, customize the generated schema. You can add metadata, modify existing definitions, or include additional information as needed.

Interactive Documentation: FastAPI provides built-in support for interactive API documentation using Swagger UI and ReDoc. This documentation is automatically generated and can be accessed via the /docs and /redoc endpoints.

Validate and Test: Ensure that your type annotations and models are consistent and correctly represent your API’s data. Test the endpoints to verify that the generated OpenAPI schema is accurate and complete.