[Zope3-dev] views have no __page_attribute__ ?

[Jim Fulton]

Jean-Marc Orliaguet wrote:
> Hi!
> 
> I've encountered a problem when trying to render views (there is no
> problem with rendering pages), but for instance with the '+' view that
> is defined in app/container/browser/configure.zcml
> 
>   <view
>       for="zope.app.container.interfaces.IContentContainer"
>       name="+"
>       menu="zmi_actions" title="Add"
>       class="zope.app.container.browser.adding.ContentAdding"
>       permission="zope.ManageContent"
>       allowed_attributes="addingInfo isSingleMenuItem hasCustomAddView">
> 
>     <page name="index.html"  template="add.pt" />
>     <page name="action.html" attribute="action" />
> 
>   </view>
> 
> 
> when called with:
> 
>     markup = view()
> 
> ['view' being the 'view' variable gotten from ZPT)
> 
> results in the following error message:
> 
> ...
>     markup = view()
>   File "/home/jmo/Zope3/src/zope/app/publisher/browser/viewmeta.py",
> line 445, in __call__
>     attr = self.__page_attribute__
> AttributeError: '+' object has no attribute '__page_attribute__'
> 
> because the __call__ method of
> zope.app.publisher.browser.viewmeta.simple expects views and pages to
> have a page attribute:
> 
>     def __call__(self, *a, **k):
>         # If a class doesn't provide it's own call, then get the attribute
>         # given by the browser default.
> 
>         attr = self.__page_attribute__
> 
> 
> With the '+' view described above, there is a default page attribute to
> use for displaying the view ('index.html') and but no page attribute
> explicitly assigned.
> 
> The following patch fixes the problem, but I'm afraid that I'm missing
> something: are views supposed to have a '__page_attribute__' or not?

They are only supposed to ave a page attribute if they are pages. :)

The directive above creates a view *with pages*.  This means that the
view itself should not a page and is not intended to be callable.

Bottom line: views created this way are not callable and are not directly
renderable.

There's a bit more complexity than I'd like in these view directives. This is
why, more and more, I tend to *define* views in Python and just register them
with the adapter or view directive.  I still do often find it useful to register
views with the view directive, mainly so I can avoid having to mention IBrowserRequest.

Jim

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