schema.Object made simple

This package introduces an experimental proof-of-concept support for object-fields (zope.schema.Object) on z3c.form and Plone for a use-case where one desires to save schema based hierarchical data on objects.

I can't say, why anyone would like to do that (instead of mapping data to containers and items), but I hope this package provides examples, how to make object-fields work with plone.autoform and Plone's KSS-validation.

This package

• provides ISubformFactory for object-widget within IAutoExtensibleForm
• implements simple Plone-style input and display widgets for object-field
• introduces refactored KSS-validation integration with support for object-field
• monkeypatches plone.z3cform's widget traversal to support object-widgets
• overrides default DataConverter for ObjectWidget's with a less invasive one
• provides a simple abstract factory class to store object-fields' values as SimpleItem-properties.

Note that this package relies on plone.app.z3cform and IPloneFormLayer it registers.

Example of Use

At first we define a simple schema we'd like to re-use as a part of other schemas:

from zope import schema
from zope.interface import invariant, Invalid

from plone.directives import form

from zope.i18nmessageid import MessageFactory as ZopeMessageFactory
_= ZopeMessageFactory("my.package")


class StartBeforeEnd(Invalid):
    __doc__ = _(u"The start or end date is invalid")


class IPeriod(form.Schema):
    start = schema.Date(
        title=_(u"period_start_label",
                default=u"Period began"),
        required=True
        )

    end = schema.Date(
        title=_(u"period_end_label",
                default=u"Period ended"),
        required=True
        )

    @invariant
    def validateStartEnd(data):
        if data.start is not None and data.end is not None:
            if data.start > data.end:
                raise StartBeforeEnd(\
                    _(u"The start date must be before the end date."))

Then we define the main schema, which re-uses the first schema:

class IWorkPeriod(form.Schema):
    title = schema.TextLine(
        title=_(u"work_title_label",
                default=u"Title"),
        required=True
        )
    description = schema.TextLine(
        title=_(u"work_description_label",
                default=u"Description"),
        required=False
        )
    period = schema.Object(
        title=_(u"work_period",
                default=u"Period"),
        schema=IPeriod,
        required=True
        )

Finally, we register an object factor, which creates SimpleItem matching our schema for z3c.form to validate and store as a property of the actual object being created or edited:

from five import grok

from zope.interface import Interface

from z3c.form.interfaces import IObjectFactory

from jyu.formwidget.object.factory import AbstractBaseFactory

from my.package.schemas import IPeriod


class PeriodFactory(AbstractBaseFactory, grok.MultiAdapter):
    grok.provides(IObjectFactory)
    grok.name("my.package.schemas.IPeriod")
    grok.adapts(Interface, Interface, Interface, Interface)

To be able to test this, you should, of course, also define and register a new content type based on the main schema (e.g. with Dexterity).

Changelog