from collections.abc import Mapping, Sequence from typing import Annotated, Any, TypedDict from annotated_doc import Doc from pydantic import BaseModel, create_model from starlette.exceptions import HTTPException as StarletteHTTPException from starlette.exceptions import WebSocketException as StarletteWebSocketException class EndpointContext(TypedDict, total=False): function: str path: str file: str line: int class HTTPException(StarletteHTTPException): """ An HTTP exception you can raise in your own code to show errors to the client. This is for client errors, invalid authentication, invalid data, etc. Not for server errors in your code. Read more about it in the [FastAPI docs for Handling Errors](https://fastapi.tiangolo.com/tutorial/handling-errors/). ## Example ```python from fastapi import FastAPI, HTTPException app = FastAPI() items = {"foo": "The Foo Wrestlers"} @app.get("/items/{item_id}") async def read_item(item_id: str): if item_id not in items: raise HTTPException(status_code=404, detail="Item not found") return {"item": items[item_id]} ``` """ def __init__( self, status_code: Annotated[ int, Doc( """ HTTP status code to send to the client. Read more about it in the [FastAPI docs for Handling Errors](https://fastapi.tiangolo.com/tutorial/handling-errors/#use-httpexception) """ ), ], detail: Annotated[ Any, Doc( """ Any data to be sent to the client in the `detail` key of the JSON response. Read more about it in the [FastAPI docs for Handling Errors](https://fastapi.tiangolo.com/tutorial/handling-errors/#use-httpexception) """ ), ] = None, headers: Annotated[ Mapping[str, str] | None, Doc( """ Any headers to send to the client in the response. Read more about it in the [FastAPI docs for Handling Errors](https://fastapi.tiangolo.com/tutorial/handling-errors/#add-custom-headers) """ ), ] = None, ) -> None: super().__init__(status_code=status_code, detail=detail, headers=headers) class WebSocketException(StarletteWebSocketException): """ A WebSocket exception you can raise in your own code to show errors to the client. This is for client errors, invalid authentication, invalid data, etc. Not for server errors in your code. Read more about it in the [FastAPI docs for WebSockets](https://fastapi.tiangolo.com/advanced/websockets/). ## Example ```python from typing import Annotated from fastapi import ( Cookie, FastAPI, WebSocket, WebSocketException, status, ) app = FastAPI() @app.websocket("/items/{item_id}/ws") async def websocket_endpoint( *, websocket: WebSocket, session: Annotated[str | None, Cookie()] = None, item_id: str, ): if session is None: raise WebSocketException(code=status.WS_1008_POLICY_VIOLATION) await websocket.accept() while True: data = await websocket.receive_text() await websocket.send_text(f"Session cookie is: {session}") await websocket.send_text(f"Message text was: {data}, for item ID: {item_id}") ``` """ def __init__( self, code: Annotated[ int, Doc( """ A closing code from the [valid codes defined in the specification](https://datatracker.ietf.org/doc/html/rfc6455#section-7.4.1). """ ), ], reason: Annotated[ str | None, Doc( """ The reason to close the WebSocket connection. It is UTF-8-encoded data. The interpretation of the reason is up to the application, it is not specified by the WebSocket specification. It could contain text that could be human-readable or interpretable by the client code, etc. """ ), ] = None, ) -> None: super().__init__(code=code, reason=reason) RequestErrorModel: type[BaseModel] = create_model("Request") WebSocketErrorModel: type[BaseModel] = create_model("WebSocket") class FastAPIError(RuntimeError): """ A generic, FastAPI-specific error. """ class DependencyScopeError(FastAPIError): """ A dependency declared that it depends on another dependency with an invalid (narrower) scope. """ class ValidationException(Exception): """Base exception for request data validation errors. Stores validation errors and optional endpoint context for enhanced error messages that include the source file, line, and path of the endpoint that triggered the validation failure. """ def __init__( self, errors: Sequence[Any], *, endpoint_ctx: EndpointContext | None = None, ) -> None: self._errors = errors self.endpoint_ctx = endpoint_ctx ctx = endpoint_ctx or {} self.endpoint_function = ctx.get("function") self.endpoint_path = ctx.get("path") self.endpoint_file = ctx.get("file") self.endpoint_line = ctx.get("line") def errors(self) -> Sequence[Any]: return self._errors def _format_endpoint_context(self) -> str: if not (self.endpoint_file and self.endpoint_line and self.endpoint_function): if self.endpoint_path: return f"\n Endpoint: {self.endpoint_path}" return "" context = f'\n File "{self.endpoint_file}", line {self.endpoint_line}, in {self.endpoint_function}' if self.endpoint_path: context += f"\n {self.endpoint_path}" return context def __str__(self) -> str: message = f"{len(self._errors)} validation error{'s' if len(self._errors) != 1 else ''}:\n" for err in self._errors: message += f" {err}\n" message += self._format_endpoint_context() return message.rstrip() class RequestValidationError(ValidationException): """Raised when incoming request data fails validation. Includes the request body that failed validation, accessible via the ``body`` attribute. Handled by default to return a 422 Unprocessable Entity response. """ def __init__( self, errors: Sequence[Any], *, body: Any = None, endpoint_ctx: EndpointContext | None = None, ) -> None: super().__init__(errors, endpoint_ctx=endpoint_ctx) self.body = body class WebSocketRequestValidationError(ValidationException): """Raised when incoming WebSocket request data fails validation. Similar to ``RequestValidationError`` but for WebSocket endpoints. Handled by default to close the WebSocket connection with a 1008 Policy Violation code. """ def __init__( self, errors: Sequence[Any], *, endpoint_ctx: EndpointContext | None = None, ) -> None: super().__init__(errors, endpoint_ctx=endpoint_ctx) class ResponseValidationError(ValidationException): """Raised when outgoing response data fails validation. Includes the response body that failed validation, accessible via the ``body`` attribute. This is raised when a response model is set and the returned data does not match it. """ def __init__( self, errors: Sequence[Any], *, body: Any = None, endpoint_ctx: EndpointContext | None = None, ) -> None: super().__init__(errors, endpoint_ctx=endpoint_ctx) self.body = body class PydanticV1NotSupportedError(FastAPIError): """ A pydantic.v1 model is used, which is no longer supported. """ class FastAPIDeprecationWarning(UserWarning): """ A custom deprecation warning as DeprecationWarning is ignored Ref: https://sethmlarson.dev/deprecations-via-warnings-dont-work-for-python-libraries """