[Zope3-Users] Re: Computed default in zope schema

[Stephan Richter]

On Friday 12 October 2007, Raphael Ritz wrote:
> Piotr Chamera wrote:
> > Hi,
> > I am new in zope (3.3) and schema and cant find how to calculate default
> > value for readonly schema field. I want to set current date as default
> > date for field (and show this in schema) - in schema I can set
> > "default = datetime.now()" but it evaluates once at zope startup, I need
> > it evaluated at attribute access time. How to do it?
>
> I have no clue but what happens if you use "default = datetime.now"
> aka without calling it. The rationale being if it's a callable
> (or maybe a string representation of a callable) it gets invoked when
> needed.
>
> In Archetypes at least we have this pattern at places while for the
> default we destinguish explicitly between a 'default' (value) and a
> 'default_method' (to be evaluated at run time).
>
> Last time this came up here (which is quite a while ago) this was
> not supported. Don't know if that changed.

z3c.form supports default value adapters, which allow you to compute a default 
value before the form is first displayed.

Regards,
Stephan
-- 
Stephan Richter
CBU Physics & Chemistry (B.S.) / Tufts Physics (Ph.D. student)
Web2k - Web Software Design, Development and Training