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Diffstat (limited to 'docs/narr/events.rst')
| -rw-r--r-- | docs/narr/events.rst | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/docs/narr/events.rst b/docs/narr/events.rst index adb0ae7b0..e54c97a88 100644 --- a/docs/narr/events.rst +++ b/docs/narr/events.rst @@ -102,6 +102,8 @@ function. The return value of a subscriber function is ignored. +.. _using_an_event_to_vary_the_request_type: + Using An Event to Vary the Request Type --------------------------------------- @@ -176,4 +178,31 @@ might also choose to use hostname request.environ['SERVER_NAME'])``) in order to "skin" your application differently based on whether the user should see the "management" (e.g. "manage.myapp.com") presentation of the application or the -"retail" presentation (e.g. "www.myapp.com"). +"retail" presentation (e.g. "www.myapp.com"). By attaching to the +request an arbitrary interface after examining the hostname or any +other information available in the request within an ``INewRequest`` +event subscriber, you can control view lookup precisely. For example, +if you wanted to have two slightly different views for requests to two +different hostnames, you might register one view with a +``request_type`` of ``.interfaces.IHostnameFoo`` and another with a +``request_type`` of ``.interfaces.IHostnameBar`` and then arrange for +an event subscriber to attach ``.interfaces.IHostnameFoo`` to the +request when the HTTP_HOST is ``foo`` and ``.interfaces.IHostnameBar`` +to the request when the HTTP_HOST is ``bar``. The appropriate view +will be called. + +You can also form an inheritance hierarchy out of ``request_type`` +interfaces. When :mod:`repoze.bfg` looks up a view, the most specific +view for the interface(s) found on the request based on standard +Python method resolution order through the interface class hierarchy +will be called. + +:mod:`repoze.bfg` also makes available as interfaces standard request +type interfaces matching HTTP verbs. When these are specified as a +``request_type`` for a view, the view will be called only when the +request has an HTTP verb (aka HTTP method) matching the request type. +For example, using the string ``repoze.bfg.interfaces.IPOST`` or the +imported interface definition itself matching that Python dotted name +as the request_type argument to a view definition is equivalent to +using the string ``POST``. See :ref:`interfaces_module` for more +information about available request types. |