[Grok-dev] Re: grok.View: Self-submitting forms, redirect, and before()

Philipp von Weitershausen philipp at weitershausen.de
Wed Jan 10 10:46:10 EST 2007

Martijn Faassen wrote:
> Philipp von Weitershausen wrote:
> [snip]
>> The redirect use case isn't properly addressed by before() currently. 
>> So I'm wondering whether we should have two separate methods for this 
>> (e.g. process() and prepare()) of which the process() method would 
>> allow to redirect somewhere, causing grok.View never to render the 
>> template. If that's overkill, then we should at least consider adding 
>> that possibility to before() (whose name would then be confusing, as 
>> it seems to already be to other people).
> I'm not tied to the name 'before' nor am I tied to the current semantics 
> of 'render'. Some suggestions:
> * could we employ the Zope 3 standard update/render technique in this? I 
> don't mean we *only* use this but perhaps we can use it as a foundation 
> to what we want.
> * try implementing process/prepare and see how the Wiki and your Herd 
> example (for instance) are affected.

After some more discussion on IRC, the change Martijn and I agreed upon was:

Index: src/grok/components.py
--- src/grok/components.py      (revision 71844)
+++ src/grok/components.py      (working copy)
@@ -137,7 +137,11 @@

      def __call__(self):
-        self.before()
+        self.update()
+        if self.request.response.getStatus() in (302, 303):
+            # Somewhere in update(), a redirect was triggered.  Don't
+            # continue rendering the template or doing anything else.
+            return

          template = getattr(self, 'template', None)
          if not template:
@@ -183,7 +187,7 @@
      def redirect(self, url):
          return self.request.response.redirect(url)

-    def before(self):
+    def update(self):

Basically, we rename before() to update() and add the semantics that a 
redirect caused in update() will stop all further rendering.

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