Don't do rendering in form's __call__ method when request is a redire…

…ction.

CHANGES.txt

@@ -5,6 +5,9 @@ CHANGES
 1.4.3 (unreleased)
 ------------------
 
+- Don't do rendering in form's __call__ method when request is a
+  redirection.
+
 - Added missing test dependency to ``z3c.ptcompat [test]``.
 
 - Fixed tests, so they work together with the current version of

src/z3c/formui/README.txt

@@ -316,8 +316,8 @@ Now our new request should know the table based form template:
 Form Macros
 -----------
 
-Load the confguration, which will make sure that all macros get registered
-correctly.
+Load the configuration, which will make sure that all macros get registered
+correctly:
 
   >>> from zope.configuration import xmlconfig
   >>> import zope.component
@@ -689,6 +689,29 @@ request and render the form again:
     </div>
   </div>
 
+Redirection
+-----------
+
+ The form doesn't bother rendering itself and its layout when
+ request is a redirection as the rendering doesn't make any sense with
+ browser requests in that case. Let's create a view that does a
+ redirection in its update method:
+
+   >>> class RedirectingView(PersonEditForm):
+   ...     def update(self):
+   ...         super(RedirectingView, self).update()
+   ...         self.request.response.redirect('http://www.google.com/')
+
+   It will return an empty string when called as a browser page.
+
+   >>> redirectView = RedirectingView(person, divRequest)
+   >>> redirectView() == ''
+   True
+
+   However, the ``render`` method will render form's template as usual:
+
+   >>> print redirectView.render()
+   <div class="viewspace">...
 
 Cleanup
 -------

src/z3c/formui/layout.py

@@ -1,6 +1,6 @@
 ##############################################################################
 #
-# Copyright (c) 2007 Zope Foundation and Contributors.
+# Copyright (c) 2007-2009 Zope Foundation and Contributors.
 # All Rights Reserved.
 #
 # This software is subject to the provisions of the Zope Public License,
@@ -21,13 +21,21 @@
 from z3c.template.interfaces import ILayoutTemplate
 
 
+REDIRECT_STATUS_CODES = (301, 302, 303)
+
+
 class FormLayoutSupport(object):
     """Layout support for forms except IAddForm."""
 
     layout = None
 
     def __call__(self):
         self.update()
+
+        if self.request.response.getStatus() in REDIRECT_STATUS_CODES:
+            # don't bother rendering when redirecting
+            return ''
+
         if self.layout is None:
             layout = zope.component.getMultiAdapter((self, self.request),
                 ILayoutTemplate)
@@ -45,6 +53,7 @@ def __call__(self):
         if self._finishedAdd:
             self.request.response.redirect(self.nextURL())
             return ''
+
         if self.layout is None:
             layout = zope.component.getMultiAdapter((self, self.request),
                 ILayoutTemplate)