relation field in dexterity

gistfile1.txt

from z3c.relationfield.schema import RelationChoice, RelationList

class IRDFFramework(form.Schema):
    """RDF descriptors"""

    rdf_framework = RelationList(
        title=_(u"RDF Framework"),
        default=[],
        value_type=RelationChoice(
            source=ObjPathSourceBinder(
                object_provides=IMetaDescriptor.__identifier__,
                navigation_tree_query={"portal_type": [
                           "vitae.content.metafolder",
                           "vitae.content.rdfmetaframework",
                           "vitae.content.metadescriptor",
                    ]}
                )
            ),
        required=False,
        )