DS.JSONSerializer#extractPolymorphicRelationship()

Returns a polymorphic relationship formatted as a JSON-API "relationship object".

http://jsonapi.org/format/#document-resource-object-relationships

relationshipOptions is a hash which contains more information about the polymorphic relationship which should be extracted: - resourceHash complete hash of the resource the relationship should be extracted from - relationshipKey key under which the value for the relationship is extracted from the resourceHash - relationshipMeta meta information about the relationship