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fc0f7bd | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 | .. _hooks:
Hooks
=====
Falcon supports *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, consider this hook that validates a POST request for
an image resource:
.. code:: python
def validate_image_type(req, resp, resource, 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 this hook to an ``on_post`` responder like so:
.. code:: python
@falcon.before(validate_image_type)
def on_post(self, req, resp):
pass
Or, suppose you had a hook that you would like to apply to *all*
responders for a given resource. In that case, you would simply
decorate the resource class:
.. code:: python
@falcon.before(extract_project_id)
class Message(object):
def on_post(self, req, resp):
pass
def on_get(self, req, resp):
pass
Falcon :ref:`middleware components <middleware>` can also be used to insert
logic before and after requests. However, unlike hooks,
:ref:`middleware components <middleware>` are triggered **globally** for all
requests.
.. automodule:: falcon
:members: before, after
:undoc-members:
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