handle_user_exception() — flask Function Reference

Architecture documentation for the handle_user_exception() function in app.py from the flask codebase.

Function python ApplicationCore Scaffolding calls 2 called by 1

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ApplicationCore→ Scaffolding→ handle_user_exception() — flask Function Reference

Dependency Diagram

graph TD
  0b9edff8_7a0a_5286_0e0e_b7d04e6a35e6["handle_user_exception()"]
  9f8cc56e_d5c4_e7a8_438a_3124c0dd5de5["Flask"]
  0b9edff8_7a0a_5286_0e0e_b7d04e6a35e6 -->|defined in| 9f8cc56e_d5c4_e7a8_438a_3124c0dd5de5
  4deafda5_fb07_c30c_ad12_a72767b1a116["full_dispatch_request()"]
  4deafda5_fb07_c30c_ad12_a72767b1a116 -->|calls| 0b9edff8_7a0a_5286_0e0e_b7d04e6a35e6
  8f350fa4_a679_30fa_08ca_b4da93c5698c["handle_http_exception()"]
  0b9edff8_7a0a_5286_0e0e_b7d04e6a35e6 -->|calls| 8f350fa4_a679_30fa_08ca_b4da93c5698c
  a89c0022_4807_bf16_9be1_6a66f3c78c9f["ensure_sync()"]
  0b9edff8_7a0a_5286_0e0e_b7d04e6a35e6 -->|calls| a89c0022_4807_bf16_9be1_6a66f3c78c9f
  style 0b9edff8_7a0a_5286_0e0e_b7d04e6a35e6 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

src/flask/app.py lines 864–894

    def handle_user_exception(
        self, ctx: AppContext, e: Exception
    ) -> HTTPException | ft.ResponseReturnValue:
        """This method is called whenever an exception occurs that
        should be handled. A special case is :class:`~werkzeug
        .exceptions.HTTPException` which is forwarded to the
        :meth:`handle_http_exception` method. This function will either
        return a response value or reraise the exception with the same
        traceback.

        .. versionchanged:: 1.0
            Key errors raised from request data like ``form`` show the
            bad key in debug mode rather than a generic bad request
            message.

        .. versionadded:: 0.7
        """
        if isinstance(e, BadRequestKeyError) and (
            self.debug or self.config["TRAP_BAD_REQUEST_ERRORS"]
        ):
            e.show_exception = True

        if isinstance(e, HTTPException) and not self.trap_http_exception(e):
            return self.handle_http_exception(ctx, e)

        handler = self._find_error_handler(e, ctx.request.blueprints)

        if handler is None:
            raise

        return self.ensure_sync(handler)(e)  # type: ignore[no-any-return]