[Zope-dev] z3c.form SequenceWIdget extract

[Mat Lehmann]

Hi,

I am using z3c.form, which is complicated but a lot more flexible than 
the old zope.formlib. Thanks for building it.

Currently, I am having a problem with the SequenceWidget. Let me 
illustrate the scenario:
I have a search-form with batching of the results - the links for the 
pages of the search contain the search parameters and the action-key as 
GET-parameters like this 
"search.html?form.widgets.text=foo&form.buttons.search=1".

With "normal" Widgets, this works perfectly well. But when my 
search-form contains a SequenceWidget, this approach breaks, because 
SequenceWidget depends on zope-functionality in some other place, which 
transforms paramters with a key-postfix of ":list" to a list of values 
(the postfix is appended to the parameter-name by the template).

The part of my application, that builds the query-string for the batch 
does however not have any knowledge about the widget-type of the 
parameters (that's intentionally to limit the dependencies to the form 
implementation).

This problem would not exist, if the extract-method of SequenceWidget 
would contain two additional lines of code:

 def extract(self, default=interfaces.NOVALUE):
        """See z3c.form.interfaces.IWidget."""
        if (self.name not in self.request and
            self.name+'-empty-marker' in self.request):
            return []
        value = self.request.get(self.name, default)
        if value != default:
 >       if not isinstance(value, (list, tuple)):
 >          value = [value]   
           for token in value:
                if token == self.noValueToken:
                    continue
                try:
                    self.terms.getTermByToken(token)
                except LookupError:
                    return default
        return value

I (hope I) can work around this problem by  subclassing SequenceWidget 
and overwrite the extract method, but I wonder, if this fix introduces 
some unknown problems and whether it can be included in the standard 
implementation.

Thanks,

Mat

-- 
Dipl. Inf. Matthias Lehmann
Software- und Web-Development
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