diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/api/viewderivers.rst | 7 | ||||
| -rw-r--r-- | docs/narr/hooks.rst | 34 |
2 files changed, 30 insertions, 11 deletions
diff --git a/docs/api/viewderivers.rst b/docs/api/viewderivers.rst index a4ec107b6..2a141501e 100644 --- a/docs/api/viewderivers.rst +++ b/docs/api/viewderivers.rst @@ -10,7 +10,8 @@ Constant representing the request ingress, for use in ``under`` arguments to :meth:`pyramid.config.Configurator.add_view_deriver`. - .. attribute:: MAPPED_VIEW + .. attribute:: VIEW - Constant representing the closest view deriver, for use in ``over`` - arguments to :meth:`pyramid.config.Configurator.add_view_deriver`. + Constant representing the :term:`view callable` at the end of the view + pipeline, for use in ``over`` arguments to + :meth:`pyramid.config.Configurator.add_view_deriver`. diff --git a/docs/narr/hooks.rst b/docs/narr/hooks.rst index 3a1ad8363..2c3782387 100644 --- a/docs/narr/hooks.rst +++ b/docs/narr/hooks.rst @@ -1617,6 +1617,14 @@ the user-defined :term:`view callable`: view pipeline interface to accept ``(context, request)`` from all previous view derivers. +.. warning:: + + Any view derivers defined ``under`` the ``rendered_view`` are not + guaranteed to receive a valid response object. Rather they will receive the + result from the :term:`view mapper` which is likely the original response + returned from the view. This is possibly a dictionary for a renderer but it + may be any Python object that may be adapted into a response. + Custom View Derivers ~~~~~~~~~~~~~~~~~~~~ @@ -1642,7 +1650,7 @@ view pipeline: response.headers['X-View-Performance'] = '%.3f' % (end - start,) return wrapper_view - config.add_view_deriver(timing_view, 'timing view') + config.add_view_deriver(timing_view) View derivers are unique in that they have access to most of the options passed to :meth:`pyramid.config.Configurator.add_view` in order to decide what @@ -1668,7 +1676,7 @@ token unless ``disable_csrf=True`` is passed to the view: require_csrf_view.options = ('disable_csrf',) - config.add_view_deriver(require_csrf_view, 'require_csrf_view') + config.add_view_deriver(require_csrf_view) def protected_view(request): return Response('protected') @@ -1691,13 +1699,19 @@ By default, every new view deriver is added between the ``decorated_view`` and ``rendered_view`` built-in derivers. It is possible to customize this ordering using the ``over`` and ``under`` options. Each option can use the names of other view derivers in order to specify an ordering. There should rarely be a -reason to worry about the ordering of the derivers. +reason to worry about the ordering of the derivers except when the deriver +depends on other operations in the view pipeline. Both ``over`` and ``under`` may also be iterables of constraints. For either option, if one or more constraints was defined, at least one must be satisfied, else a :class:`pyramid.exceptions.ConfigurationError` will be raised. This may be used to define fallback constraints if another deriver is missing. +Two sentinel values exist, :attr:`pyramid.viewderivers.INGRESS` and +:attr:`pyramid.viewderivers.VIEW`, which may be used when specifying +constraints at the edges of the view pipeline. For example, to add a deriver +at the start of the pipeline you may use ``under=INGRESS``. + It is not possible to add a view deriver under the ``mapped_view`` as the :term:`view mapper` is intimately tied to the signature of the user-defined :term:`view callable`. If you simply need to know what the original view @@ -1707,8 +1721,12 @@ deriver. .. warning:: - Any view derivers defined ``under`` the ``rendered_view`` are not - guaranteed to receive a valid response object. Rather they will receive the - result from the :term:`view mapper` which is likely the original response - returned from the view. This is possibly a dictionary for a renderer but it - may be any Python object that may be adapted into a response. + The default constraints for any view deriver are ``over='rendered_view'`` + and ``under='decorated_view'``. When escaping these constraints you must + take care to avoid cyclic dependencies between derivers. For example, if + you want to add a new view deriver before ``secured_view`` then + simply specifying ``over='secured_view'`` is not enough, because the + default is also under ``decorated view`` there will be an unsatisfiable + cycle. You must specify a valid ``under`` constraint as well, such as + ``under=INGRESS`` to fall between INGRESS and ``secured_view`` at the + beginning of the view pipeline. |