How to Handle 422 Errors When Sending JSON POST Requests in FastAPI?

FastAPI: Handling POST Request with JSON Data

When working with FastAPI APIs, encountering a 422 Unprocessable Entity error code can be frustrating, especially when sending JSON data via POST requests. This error occurs when the request body does not match the expected format or is missing required fields.

To resolve this issue, consider the following options to define an endpoint that expects JSON data:

Option 1: Pydantic Models

Utilize Pydantic models to create a structured representation of your request body. This approach allows for easy validation and documentation of expected parameters.

Option 2: Body Parameters

Employ the Body parameter embed to declare the expected JSON payload directly in the function signature. This method simplifies parameter handling.

Option 3: Dict Type

Define the request body as a dict[Any, Any] or dict if using Python 3.9 . While this option does not provide custom validations, it offers flexibility.

Option 4: Starlette's Request Object

Access the request body directly through the Starlette Request object. Note that this approach requires the use of async def and requires handling JSON parsing manually.

Testing Options

To test the above options, consider using the Python requests library or the JavaScript Fetch API. Ensure that the request headers include the appropriate Content-Type (e.g., application/json) and that the body contains the required JSON data.

The above is the detailed content of How to Handle 422 Errors When Sending JSON POST Requests in FastAPI?. For more information, please follow other related articles on the PHP Chinese website!