errorhandler() — flask Function Reference

Architecture documentation for the errorhandler() function in scaffold.py from the flask codebase.

Function python ApplicationCore Scaffolding calls 1 called by 1

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ApplicationCore→ Scaffolding→ errorhandler() — flask Function Reference

Dependency Diagram

graph TD
  b1d22eae_0124_5afd_3df0_850086c3d41b["errorhandler()"]
  a813bd5c_bf41_d926_8dde_6a113d5e0018["Scaffold"]
  b1d22eae_0124_5afd_3df0_850086c3d41b -->|defined in| a813bd5c_bf41_d926_8dde_6a113d5e0018
  da9ef7e9_1774_18fd_3b97_c5ab1886cd8d["app_errorhandler()"]
  da9ef7e9_1774_18fd_3b97_c5ab1886cd8d -->|calls| b1d22eae_0124_5afd_3df0_850086c3d41b
  eba08275_fc06_f17e_1fee_04ddb9a4e448["register_error_handler()"]
  b1d22eae_0124_5afd_3df0_850086c3d41b -->|calls| eba08275_fc06_f17e_1fee_04ddb9a4e448
  style b1d22eae_0124_5afd_3df0_850086c3d41b fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

src/flask/sansio/scaffold.py lines 598–639

    def errorhandler(
        self, code_or_exception: type[Exception] | int
    ) -> t.Callable[[T_error_handler], T_error_handler]:
        """Register a function to handle errors by code or exception class.

        A decorator that is used to register a function given an
        error code.  Example::

            @app.errorhandler(404)
            def page_not_found(error):
                return 'This page does not exist', 404

        You can also register handlers for arbitrary exceptions::

            @app.errorhandler(DatabaseError)
            def special_exception_handler(error):
                return 'Database connection failed', 500

        This is available on both app and blueprint objects. When used on an app, this
        can handle errors from every request. When used on a blueprint, this can handle
        errors from requests that the blueprint handles. To register with a blueprint
        and affect every request, use :meth:`.Blueprint.app_errorhandler`.

        .. versionadded:: 0.7
            Use :meth:`register_error_handler` instead of modifying
            :attr:`error_handler_spec` directly, for application wide error
            handlers.

        .. versionadded:: 0.7
           One can now additionally also register custom exception types
           that do not necessarily have to be a subclass of the
           :class:`~werkzeug.exceptions.HTTPException` class.

        :param code_or_exception: the code as integer for the handler, or
                                  an arbitrary exception
        """

        def decorator(f: T_error_handler) -> T_error_handler:
            self.register_error_handler(code_or_exception, f)
            return f

        return decorator