Dexterity Relationfield ComponentLookupError

Development Developing for Plone
,
1

Trying to set a relation field to a Dexterity content type i get the following error when i try to create new content:

2017-02-22 10:12:25 ERROR Zope.SiteErrorLog 1487754745.270.794031734041 http://ploneprod.semicinternet.local:18081/fs-prova/testsgerard/++add++Banner
Traceback (innermost last):
  Module ZPublisher.Publish, line 138, in publish
  Module ZPublisher.mapply, line 77, in mapply
  Module ZPublisher.Publish, line 48, in call_object
  Module plone.z3cform.layout, line 66, in __call__
  Module plone.z3cform.layout, line 50, in update
  Module plone.dexterity.browser.add, line 130, in update
  Module plone.z3cform.fieldsets.extensible, line 59, in update
  Module plone.z3cform.patch, line 30, in GroupForm_update
  Module z3c.form.group, line 132, in update
  Module z3c.form.form, line 136, in updateWidgets
  Module z3c.form.field, line 257, in update
  Module zope.component._api, line 109, in getMultiAdapter
ComponentLookupError: ((<z3c.relationfield.schema.Relation object at 0x7f29634db9d0>, <HTTPRequest, URL=http://ploneprod.semicinternet.local:18081/fs-prova/testsgerard/++add++Banner>), <InterfaceClass z3c.form.interfaces.IFieldWidget>, u'')

I read around the internet and seems that it could be because it doesn't finds the view, but i don't know why:

My interfaces.py file:
# -- coding: utf-8 --
"""Module where all interfaces, events and exceptions live."""

from contenttype.banner import _
from zope import schema
from plone.supermodel import model
from zope.publisher.interfaces.browser import IDefaultBrowserLayer
from plone.namedfile import field
from z3c.relationfield import Relation


class IContenttypeBannerLayer(IDefaultBrowserLayer):
    """Marker interface that defines a browser layer."""


class IBanner(model.Schema):

    title = schema.TextLine(
        title=_(u'Title'),
        required=True,
    )

    description = schema.Text(
        title=_(u'Description'),
        required=False,
    )

    image = field.NamedImage(
        title=_(u'Image'),
        required=True,
    )

    button_text = schema.TextLine(
        title=_(u'Button text'),
        required=True,
        default=_(u'More information'),
    )

    external_link = schema.URI(
        title=_(u'External link'),
        required=False,
    )

    internal_link = Relation(
        title=_(u'Internal link'),
        required=False,
    )



from z3c.relationfield.interfaces import IHasRelations
from persistent import Persistent
from zope.interface import implements

class Banner(Persistent):

  implements(IBanner, IHasRelations)
  
  def __init__(self):
    self.internal_link = None
2

I think you should use the Field in your Schema:

from contenttype.banner import _
from zope import schema
from plone.supermodel import model
from zope.publisher.interfaces.browser import IDefaultBrowserLayer
from plone.namedfile import field
from plone.app.vocabularies.catalog import CatalogSource
from z3c.relationfield.schema import RelationChoice


class IContenttypeBannerLayer(IDefaultBrowserLayer):
    """Marker interface that defines a browser layer."""


class IBanner(model.Schema):

    title = schema.TextLine(
        title=_(u'Title'),
        required=True,
    )

    description = schema.Text(
        title=_(u'Description'),
        required=False,
    )

    image = field.NamedImage(
        title=_(u'Image'),
        required=True,
    )

    button_text = schema.TextLine(
        title=_(u'Button text'),
        required=True,
        default=_(u'More information'),
    )

    external_link = schema.URI(
        title=_(u'External link'),
        required=False,
    )
    
    internal_link = RelationChoice(
        title=_(u"Internal Link"),
        vocabulary='plone.app.vocabularies.Catalog',
        required=False
)



from zope.interface import implements
from plone.dexterity.content import Item
class Banner(Item):
    
    implements(IBanner)
  
    def __init__(self):
        pass

Another way: use the behavior in the profile/types/banner.xml
plone.app.relationfield.behavior.IRelatedItems
check plone.app.contenttypes for Example or read the Training Docs for Examples