Using dexterity behaviors to provide a method - plone

Question

I've been using a schema behavior with no problem, but I want to also have a method that provides some logic. Right now I have
class IMyFoo(form.Schema):
requester = schema.TextLine(title=_(u"Requestor"),
required=False,
)
def foo(self):
""" foo """
alsoProvides(IMyFoo, IFormFieldProvider)
And in the zcml
<plone:behavior
title="My behavior"
description="Some desc"
provides=".behaviors.IMyFoo"
for=".interfaces.ISomeInterface"
/>
I included IMyFoo in the behaviors section of a content type in portal_types. This gives me the schema but not that foo() method. So I tried to add a factory for it from reading http://plone-training.readthedocs.org/en/latest/behaviors2.html with the following code
class MyFoo(object):
def foo(self):
return 'bar'
And in the zcml
<plone:behavior
title="My behavior"
description="Some desc"
provides=".behaviors.IMyFoo"
factory=".behaviors.MyFoo"
for=".interfaces.ISomeInterface"
/>
But this didn't seem to make a difference, or at least, I don't know how to access that method. The closest I've been able to come is the following:
class IMyFoo(Interface):
""" Marker """
class MyFoo(object):
def __init__(self, context):
self.context = context
def foo(self):
return 'bar'
<adapter for=".interfaces.ISomeInterface"
factory=".behaviors.MyFoo"
provides=".behaviors.IMyFoo" />
I put IMyFoo in the behaviors attribute in the fti, and then call it by walking through all behaviors with something like
behavior = resolveDottedName(context.portal_types.getTypeInfo(context.portal_type).behaviors[-1]))
behavior(self).myfoo()
Surely going through the FTI like that is not the proper way to do it. But I'm at a loss at this point. In Archetypes I would just make a mixin class and inherit it with any content type I wanted to use it. I could do the same here, but my understanding is that behaviors are supposed to be a replacement for them, so I'd like to figure out how to use this preferred method.

Answer 1

As you've discovered, the schema class really is just an interface. It can't provide any methods. To provide more functionality, you need to connect your behavior interface to a factory class that adapts a dexterity object to provide your interface.
So, if your behaviors.py looks like this:
# your imports plus:
from plone.dexterity.interfaces import IDexterityContent
from zope.component import adapts
from zope.interface import implements
class IMyFoo(form.Schema):
requester = schema.TextLine(
title=_(u"Requestor"),
required=False,
)
def foo(self):
""" foo """
alsoProvides(IMyFoo, IFormFieldProvider)
class MyFoo(object):
implements(IMyFoo)
adapts(IDexterityContent)
def __init__(self, context):
self.context = context
def foo(self):
return 'bar'
Then your one-and-only zcml declaration would be:
<plone:behavior
title="My behavior name"
description="Behavior description"
provides=".behavior.IMyFoo"
factory=".behavior.MyFoo"
for="plone.dexterity.interfaces.IDexterityContent"
/>
And, you would reach your method with code like:
IMyFoo(myFooishObject).foo()
Note the use of IDexterityContent. You're creating a behavior that could be applied to any Dexterity content. So, the behavior adapter should be for that very general interface.