Exceptions

HTTP error classes following RFC 9457 Problem Details. Import from fastapi_views.exceptions.

Every APIError subclass automatically:

• generates a typed Pydantic model (cls.model) with constant status, title, and type fields
• is registered as a possible response in the OpenAPI spec for any route that declares it
• is converted to a JSON response by the error handler installed by configure_app

Built-in error classes

Class	Status
BadRequest	400
Unauthorized	401
Forbidden	403
NotFound	404
Conflict	409
UnprocessableEntity	422
Throttled	429
InternalServerError	500
Unavailable	503

Defining custom errors

Subclass APIError and set status. The title and type are derived automatically from the class name and HTTP status code:

from fastapi_views.exceptions import APIError
from starlette.status import HTTP_402_PAYMENT_REQUIRED

class PaymentRequired(APIError):
    """Payment is required to access this resource."""
    status = HTTP_402_PAYMENT_REQUIRED

Add extra fields to the error model by annotating them on the class:

class RateLimited(APIError):
    """Rate limit exceeded."""
    status = 429
    retry_after: int  # becomes a required field in the error model

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