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Diffstat (limited to 'docs/narr/renderers.rst')
| -rw-r--r-- | docs/narr/renderers.rst | 72 |
1 files changed, 51 insertions, 21 deletions
diff --git a/docs/narr/renderers.rst b/docs/narr/renderers.rst index 3804fcf42..a80c5a9c2 100644 --- a/docs/narr/renderers.rst +++ b/docs/narr/renderers.rst @@ -3,18 +3,10 @@ Renderers ========= -In the :ref:`views_chapter` chapter, we said that a view callable must -return a :term:`Response` object. We lied. A :term:`renderer` is a service -that attempts to convert a non-Response return value of a function, class, or -instance that acts as a :term:`view callable` to a :term:`Response` object. - -Overview --------- - -A view needn't *always* return a Response object. If a view happens to -return something which does not implement the Pyramid Response interface, -:app:`Pyramid` will attempt to use a :term:`renderer` to construct a -response. For example: +A view needn't *always* return a :term:`Response` object. If a view +happens to return something which does not implement the Pyramid +Response interface, :app:`Pyramid` will attempt to use a +:term:`renderer` to construct a response. For example: .. code-block:: python :linenos: @@ -22,6 +14,7 @@ response. For example: from pyramid.response import Response from pyramid.view import view_config + @view_config(renderer='json') def hello_world(request): return {'content':'Hello!'} @@ -396,21 +389,17 @@ documentation in :ref:`request_module`. .. _adding_and_overriding_renderers: -Adding and Overriding Renderers -------------------------------- +Adding and Changing Renderers +----------------------------- New templating systems and serializers can be associated with :app:`Pyramid` renderer names. To this end, configuration declarations can be made which -override an existing :term:`renderer factory`, and which add a new renderer +change an existing :term:`renderer factory`, and which add a new renderer factory. Renderers can be registered imperatively using the :meth:`pyramid.config.Configurator.add_renderer` API. -.. note:: The tasks described in this section can also be performed via - :term:`declarative configuration`. See - :ref:`zcml_adding_and_overriding_renderers`. - For example, to add a renderer which renders views which have a ``renderer`` attribute that is a path that ends in ``.jinja2``: @@ -553,7 +542,7 @@ set as ``renderer=`` in the view configuration. See also :ref:`renderer_directive` and :meth:`pyramid.config.Configurator.add_renderer`. -Overriding an Existing Renderer +Changing an Existing Renderer ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can associate more than one filename extension with the same existing @@ -570,7 +559,7 @@ extension for the same kinds of templates. For example, to associate the After you do this, :app:`Pyramid` will treat templates ending in both the ``.pt`` and ``.zpt`` filename extensions as Chameleon ZPT templates. -To override the default mapping in which files with a ``.pt`` extension are +To change the default mapping in which files with a ``.pt`` extension are rendered via a Chameleon ZPT page template renderer, use a variation on the following in your application's startup code: @@ -592,3 +581,44 @@ the ``name`` attribute to the renderer tag: config.add_renderer(None, 'mypackage.json_renderer_factory') +Overriding A Renderer At Runtime +-------------------------------- + +.. warning:: This is an advanced feature, not typically used by "civilians". + +In some circumstances, it is necessary to instruct the system to ignore the +static renderer declaration provided by the developer in view configuration, +replacing the renderer with another *after a request starts*. For example, +an "omnipresent" XML-RPC implementation that detects that the request is from +an XML-RPC client might override a view configuration statement made by the +user instructing the view to use a template renderer with one that uses an +XML-RPC renderer. This renderer would produce an XML-RPC representation of +the data returned by an arbitrary view callable. + +To use this feature, create a :class:`pyramid.events.NewRequest` +:term:`subscriber` which sniffs at the request data and which conditionally +sets an ``override_renderer`` attribute on the request itself, which is the +*name* of a registered renderer. For example: + +.. code-block:: python + :linenos: + + from pyramid.event import subscriber + from pyramid.event import NewRequest + + @subscriber(NewRequest) + def set_xmlrpc_params(event): + request = event.request + if (request.content_type == 'text/xml' + and request.method == 'POST' + and not 'soapaction' in request.headers + and not 'x-pyramid-avoid-xmlrpc' in request.headers): + params, method = parse_xmlrpc_request(request) + request.xmlrpc_params, request.xmlrpc_method = params, method + request.is_xmlrpc = True + request.override_renderer = 'xmlrpc' + return True + +The result of such a subscriber will be to replace any existing static +renderer configured by the developer with a (notional, nonexistent) XML-RPC +renderer if the request appears to come from an XML-RPC client. |