How to write a custom error handler

[cdruet]

Great module. Very useful.

I'ld like to customise the handler for 500 to do a rollback. It should be available to all blueprints (in my case) but there could be a use for specifying which blueprints use this customised handler.

In the intro, you explicitly mention that:

Instead you can use your own response implementation passed as argument to ErrorHandler class: it must be a decorator and must take 3 args, a dict response, status code and dict headers.

Could you tell me a bit more about how to do that? Would you have a small example?

[cs91chris]

Hi, for a customised error response available to all blueprint you have to implement a function with the same interface of this, for example:

def response_builder(self, f):
    @wraps(f)
    def wrapper(*args, **kwargs):
        r, s, h = f(*args, **kwargs)
        # your own custom implementation
        return flask.Response(...)

    return wrapper

and use with:

error = ErrorHandler()
error.init_app(app, response=response_builder)

Instead for a specific blueprint called custom_bp, decorate your custom function, like this:

@error.register(custom_bp)
def custom_error_handler(exc):
    return str(exc), 500, {'Content-Type': 'text/plain'}