tomany.py

from tastypie.fields import ToMany

class HrefToMany(ToMany):
    """Like a normal ToMany, except dehyrates to a link to a filtered collection"""

    def uri_template(self):
        if not hasattr(self, '_uri_template'):
            self._uri_template = self.make_uri_template()
        return self._uri_template


    def make_uri_template(self):
        related = self.get_related_resource(None)
        base = related.get_resource_list_uri()
        
        # This may fail
        field_name = next(k for k,v in related.fields.iteritems() if v == self._cls)
        return ''.join([base, "?", field_name, '__id=%s'])
        

    def dehydrate(self, bundle):
        if not bundle.obj or not bundle.obj.pk:
            if not self.null:
                raise ApiFieldError("The model '%r' does not have a primary key and can not be used in a ToMany context." % bundle.obj)
            return None
        return self.uri_template % (bundle.obj.pk)