Method distinct

mongoengine/queryset/base.py:980–1036

Return a list of distinct values for a given field. :param field: the field to select distinct values from .. note:: This is a command and won't take ordering or limit into account.

(self, field)

        return queryset

    def distinct(self, field):
        """Return a list of distinct values for a given field.

        :param field: the field to select distinct values from

        .. note:: This is a command and won't take ordering or limit into
           account.
        """
        queryset = self.clone()

        try:
            field = self._fields_to_dbfields([field]).pop()
        except LookUpError:
            pass

        raw_values = queryset._cursor.distinct(field)
        if not self._auto_dereference:
            return raw_values

        distinct = self._dereference(raw_values, 1, name=field, instance=self._document)

        doc_field = self._document._fields.get(field.split(".", 1)[0])
        instance = None

        # We may need to cast to the correct type eg. ListField(EmbeddedDocumentField)
        EmbeddedDocumentField = _import_class("EmbeddedDocumentField")
        ListField = _import_class("ListField")
        GenericEmbeddedDocumentField = _import_class("GenericEmbeddedDocumentField")
        if isinstance(doc_field, ListField):
            doc_field = getattr(doc_field, "field", doc_field)
        if isinstance(doc_field, (EmbeddedDocumentField, GenericEmbeddedDocumentField)):
            instance = getattr(doc_field, "document_type", None)

        # handle distinct on subdocuments
        if "." in field:
            for field_part in field.split(".")[1:]:
                # if looping on embedded document, get the document type instance
                if instance and isinstance(
                    doc_field, (EmbeddedDocumentField, GenericEmbeddedDocumentField)
                ):
                    doc_field = instance
                # now get the subdocument
                doc_field = getattr(doc_field, field_part, doc_field)
                # We may need to cast to the correct type eg. ListField(EmbeddedDocumentField)
                if isinstance(doc_field, ListField):
                    doc_field = getattr(doc_field, "field", doc_field)
                if isinstance(
                    doc_field, (EmbeddedDocumentField, GenericEmbeddedDocumentField)
                ):
                    instance = getattr(doc_field, "document_type", None)

        if instance and isinstance(
            doc_field, (EmbeddedDocumentField, GenericEmbeddedDocumentField)
        ):
            distinct = [instance(**doc) for doc in distinct]

        return distinct