Error Handler Extension Point


The extension point abbreviation is errhandler.

Error handler, this extension point is also very simple, return the errhandler field through register, this field requires the format is {http-code: error-view-func, other-code: other-error-view-func}, and the key is a standard HTTP code (such as 404, 403, 500), the value is an error handler view function, and supports multiple error code handling.

However, there is now a new format: [{error=exception_class, handler=func}, {error=err_code, handler=func}], this form allows you to use http-code to handle error codes while allowing a custom exception class to be passed in. And the associated processor (capturing the handler for this exception class), please refer to the Flask documentation for this class-based form of code.

The Flask-PluginKit loads errhandler via _error_handler(), this method will detect errhandler rules and specific content.

It should be noted that if multiple duplicate error handling functions are eventually overwritten, only one is valid. The error handling function can be written in the official documentation is flask-error-handlers.


  • Plugin registration for errhandler

from flask import jsonify

def permission_deny(error):
    return jsonify(dict(status=403, msg="permission deny")),403

class ApiError(Exception):

    def __init__(self, code, message, status_code=200):
        super(ApiError, self).__init__()
        self.code = code
        self.message = message
        self.status_code = status_code

    def to_dict(self):
        return dict(code=self.code, msg=self.message)

def handle_api_error(e):
    #: e is an instance of an exception class
    response = jsonify(e.to_dict())
    response.status_code = e.status_code
    return response

def raise_api_error_view():
    #: Actively triggering ApiError in the view will be intercepted by
    #: handle_api_error and return json response.
    raise ApiError(10000, "err_message")

def register():
    return {
        'vep': dict(rule='/api_error', view_func=raise_api_error_view),
        'errhandler': [
            dict(error=403, handler=permission_deny),
            dict(error=ApiError, handler=handle_api_error)