AW: [Zope-dev] z3c.form SequenceWIdget extract

15 Mar 2008

      Hi Mat
...
Betreff: [Zope-dev] z3c.form SequenceWIdget extract
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).
Can you give a smaple ot the search string which you are using
if it contains a sequence widget? I guess this string is wrong
and this ends in none sequence data at the server side.

If I'm right, now you are trying to convert this simple data
string into a sequence, right?

Try to build a sequence of values as:

search.html?text=foo&text=bar

that's the right way to send sequence data and will give you 
the result:

text = ['foo', 'bar']

at the server side.

Regards 
Roger Ineichen
...
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
Käthe-Kollwitz-Straße 6
99734 Nordhausen
fon:   +49 3631 470652
mobil: +49 170 5176774
eMail: info@matlehmann.de
web:   http://www.matlehmann.de