Dexterity edit form which disables constraint checks for certain fields

edit.py

"""
Dexterity edit form which disables constraint checks for certain fields

use at your own risk as the error handling is manipulated!

configure.zcml:

 <browser:page
      for="plone.dexterity.interfaces.IDexterityContent"
      layer="plone.addon.interfaces.IPloneAddonLayer"
      name="edit"
      class=".edit.DefaultEditView"
      permission="cmf.ModifyPortalContent"
      />
      
"""

from plone.dexterity.browser.edit import DefaultEditForm
from plone.dexterity.interfaces import IDexterityEditForm
from plone.z3cform import layout
from wageindicator.addon.content.site import Site
from zope.interface import classImplements
from zope.schema.interfaces import ConstraintNotSatisfied

import logging
logger = logging.getLogger(__name__)

FIELDS = (
    'image_reference',
    'link_reference',
    'cta_image',
)

class AddonEditForm(DefaultEditForm):

    def extractData(self):
        """ Override the error which is returned when a object outside a 
        subsite is referenced.
        """

        def get_object(value):
            return value.context.args[0]

        data, errors = super(AddonEditForm, self).extractData()

        ignore_errors = {}

        for index, error_value in enumerate(errors):
            name = error_value.field.getName()

            if name in FIELDS and \
                    type(error_value.error) == ConstraintNotSatisfied:
                context = get_object(error_value)

                if Site.resolve(context):
                    continue  # ignore if the object is in the WI site

                ignore_errors[index] = error_value

        if ignore_errors:
            errors = list(errors)

            for index, error_value in ignore_errors.items():
                errors.pop(index)

                name = error_value.field.getName()

                data[name] = get_object(error_value)

                logger.info(
                    'Ignoring constraint error for {0} field'.format(name)
                )

            errors = tuple(errors)

        return data, errors


DefaultEditView = layout.wrap_form(AddonEditForm)
classImplements(DefaultEditView, IDexterityEditForm)