[Zope3-Users] Re: Sending data to widgets

[Gary Poster]

On Apr 18, 2006, at 10:19 AM, Frank Burkhardt wrote:

> Hi,
>
> On Tue, Apr 18, 2006 at 04:04:43PM +0200, Philipp von Weitershausen  
> wrote:
>> Hi Frank,
>>
>>> My problem is not about data the widget should display but about  
>>> data
>>> that controls the widget's behaviour.
>>>
>>> In this case my form consists of some widgets representing a  
>>> schema interface
>>> plus a special "I18NController" widget which is e.g. used to  
>>> define, in which
>>> order different language versions of the form's fields should be  
>>> displayed.
>>> (->This is about I18Nd content, stored in dictionary-fields)
>>>
>>> Problem is: Some of the Widgets that should receive data from the  
>>> "I18NController"
>>> are not known to the formlib because they are multiadapter- 
>>> queried inside e.g.
>>> a ListInputWidget. The request + the context seem to be the only  
>>> objects accessible
>>> to all the widgets - but I don't want to store language order  
>>> information in zodb which
>>> leaves the request object only.
>>>
>>> Is there really no chance to store information as attributes of  
>>> the request?
>>
>> Perhaps there is, but I would still advise against it.
>>
>> In this case I would recommend to make use of the adaption feature of
>> zope.formlib. The "context" of the form and widgets doesn't  
>> necessarily
>> have to be the persistent object itself. It can be an adapter.  
>> That way
>> you can generate schema-based forms using schemas that aren't even
>> provided by the object you're editing. zope.formlib will  
>> automatically
>> adapt the object to the schema. The adapter will be responsible for
>> mediating between formlib and the object.
>>
>> An example is the Metadata tab in the ZMI. The schema is something  
>> like
>> IZopeDublinCore (at least some Dublin Core metadata), though no  
>> object
>> really provides this data. However, there's an adapter that the  
>> data can
>> be written to and that knows how to modify the object accordingly.
>>
>> In your case your adapter would probably behave like the original
>> "context" except that it also stores this i18n ordering that you  
>> don't
>> want to be stored persistently but still need for the form.
>
> Perhaps it's overkill to write adapter for all my content objects.  
> I think
> I found a solution. The Request object might be RO but I can  
> smuggle an object
> reference inside the reponse headers and removed it after all the  
> widgets are
> processed.

augh! :-)

Philipp is leading you correctly.  I might even be tempted to write a  
custom form that directly set the data for the widgets myself; maybe  
that would be a quicker and easier approach to the same road.

If you still don't want to listen to him, please don't do the  
response hack you are talking about.  the request has an  
`annotations` attribute which experts can use to stash things away.   
Beware: this is a road that has bitten many in Zope 2, and is easily  
abused.

Gary