gistfile1.py

        counts = Metadata.group(key={'metadata_type':1},
                                condition={"owner" : self.owner.id,
                                           "attributes.attribute_type" : {"$in", self.md_fields}
                                           },
                                initial={"count":0},
                                reduce_f="""function (current, result) { result.count++}""",
                                finalize_f=None)