conditionatl_full.py

from tastypie.fields import ToManyField

class ConditionalRelatedField(ToManyField):
    truthy = set('1', 'true', 'yes')

    def dehydrate_related(self, bundle, related_resource):
        full = bundle.request.GET.get('include_entitites', '').lower()
        if full not in self.truthy:
            return related_resource.get_resource_uri(bundle)
        else:
            bundle = related_resource.build_bundle(obj=related_resource.instance, request=bundle.request)
            return related_resource.full_dehydrate(bundle)