diff options
| -rw-r--r-- | docs/narr/hooks.rst | 29 |
1 files changed, 22 insertions, 7 deletions
diff --git a/docs/narr/hooks.rst b/docs/narr/hooks.rst index c54b213f1..6d0a2a5a3 100644 --- a/docs/narr/hooks.rst +++ b/docs/narr/hooks.rst @@ -1481,7 +1481,7 @@ method. For example: phash = text def __call__(self, context, request): - return getattr(context, 'content_type', None) == self.val + return request.content_type == self.val The constructor of a predicate factory takes two arguments: ``val`` and ``config``. The ``val`` argument will be the argument passed to @@ -1500,13 +1500,28 @@ with the name and the value serialized. The result of ``phash`` is not seen in output anywhere, it just informs the uniqueness constraints for view configuration. -The ``__call__`` method of a predicate factory must accept a resource -(``context``) and a request, and must return ``True`` or ``False``. It is the -"meat" of the predicate. +The ``__call__`` method differs depending on whether the predicate is used as +a :term:`view predicate` or a :term:`route predicate`: -You can use the same predicate factory as both a view predicate and as a route -predicate, but you'll need to call ``add_view_predicate`` and -``add_route_predicate`` separately with the same factory. +- When used as a route predicate, the ``__call__`` signature is + ``(info, request)``. The ``info`` object is a dictionary containing two + keys: ``match`` and ``route``. ``info['match']`` is the matchdict containing + the patterns matched in the route pattern. ``info['route']`` is the + :class:`pyramid.interfaces.IRoute` object for the current route. + +- When used as a view predicate, the ``__call__`` signature is + ``(context, request)``. The ``context`` is the result of :term:`traversal` + performed using either the route's :term:`root factory` or the app's + :term:`default root factory`. + +In both cases the ``__call__`` method is expected to return ``True`` or +``False``. + +It is possible to use the same predicate factory as both a view predicate and +as a route predicate, but they'll need to handle the ``info`` or ``context`` +argument specially (many predicates do not need this argument) and you'll need +to call ``add_view_predicate`` and ``add_route_predicate`` separately with +the same factory. .. _subscriber_predicates: |