Hooks

Falcon supports both before and after hooks. You install a hook simply by applying one of the decorators below either to an individual responder or to an entire resource.

For example, suppose you had a hook like this:

def validate_image_type(req, resp, params):
    if req.content_type not in ALLOWED_IMAGE_TYPES:
        msg = 'Image type not allowed. Must be PNG, JPEG, or GIF'
        raise falcon.HTTPBadRequest('Bad request', msg)

You would attach the hook to an on_post responder like so:

@falcon.before(validate_image_type)
def on_post(self, req, resp):
    pass

Or, if you had a hook that you would like to applied to all responders for a given resource, you could install the hook like this:

@falcon.before(extract_project_id)
class Message(object):
    pass

And you can apply hooks globally by passing them into the API class initializer (note that this does not require the use of a decorator):

falcon.API(before=[extract_project_id])

falcon

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Hooks

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