Method _save_update

mongoengine/document.py:551–587

Update an existing document. Helper method, should only be used inside save().

(self, doc, save_condition, write_concern)

        return select_dict

    def _save_update(self, doc, save_condition, write_concern):
        """Update an existing document.

        Helper method, should only be used inside save().
        """
        collection = self._get_collection()
        object_id = doc["_id"]
        created = False

        select_dict = {}
        if save_condition is not None:
            select_dict = transform.query(self.__class__, **save_condition)

        select_dict["_id"] = object_id

        select_dict = self._integrate_shard_key(doc, select_dict)

        update_doc = self._get_update_doc()
        if update_doc:
            upsert = save_condition is None
            with set_write_concern(collection, write_concern) as wc_collection:
                last_error = wc_collection.update_one(
                    select_dict, update_doc, upsert=upsert
                ).raw_result
            if not upsert and last_error["n"] == 0:
                raise SaveConditionError(
                    "Race condition preventing document update detected"
                )
            if last_error is not None:
                updated_existing = last_error.get("updatedExisting")
                if updated_existing is False:
                    created = True
                    # !!! This is bad, means we accidentally created a new,
                    # potentially corrupted document. See
                    # https://github.com/MongoEngine/mongoengine/issues/564

        return object_id, created

    def cascade_save(self, **kwargs):
        """Recursively save any references and generic references on the