[Grok-dev] Re: Using martian to load schemata

[Martin Aspeli]

Martijn Faassen <faassen <at> startifact.com> writes:

> Yes, this is a good point. grok.Fields() (or formlib FormFields) work 
> during import time, so you can't get the schema yet.
> 
> You can work around this, but you'd need to make it a property:
> 
> class MyForm(grok.EditForm):
>      @property
>      def form_fields(self):
>           return grok.Fields(IMySchema)
> 
> This way grok.Fields will only be executed during runtime, as the form 
> is being rendered.
> 
> We run into similar problems when generating a schema from RDB schema. 
> It's unfortunate the form code assumes the schemas need to exist already 
> during import time. I wonder whether z3c.form has a better way?

Sounds like a bit of a general problem. If you want to be able to use Zope 
3 components in grokkers/martian directives, you're going to get into funny
dependency loops, I think.

Martin