Method watch

pymongo/synchronous/database.py:348–477

Watch changes on this database. Performs an aggregation with an implicit initial ``$changeStream`` stage and returns a :class:`~pymongo.change_stream.DatabaseChangeStream` cursor which iterates over changes on all collections in this database. Introduced in

(
        self,
        pipeline: Optional[_Pipeline] = None,
        full_document: Optional[str] = None,
        resume_after: Optional[Mapping[str, Any]] = None,
        max_await_time_ms: Optional[int] = None,
        batch_size: Optional[int] = None,
        collation: Optional[_CollationIn] = None,
        start_at_operation_time: Optional[Timestamp] = None,
        session: Optional[ClientSession] = None,
        start_after: Optional[Mapping[str, Any]] = None,
        comment: Optional[Any] = None,
        full_document_before_change: Optional[str] = None,
        show_expanded_events: Optional[bool] = None,
    )

        )

    def watch(
        self,
        pipeline: Optional[_Pipeline] = None,
        full_document: Optional[str] = None,
        resume_after: Optional[Mapping[str, Any]] = None,
        max_await_time_ms: Optional[int] = None,
        batch_size: Optional[int] = None,
        collation: Optional[_CollationIn] = None,
        start_at_operation_time: Optional[Timestamp] = None,
        session: Optional[ClientSession] = None,
        start_after: Optional[Mapping[str, Any]] = None,
        comment: Optional[Any] = None,
        full_document_before_change: Optional[str] = None,
        show_expanded_events: Optional[bool] = None,
    ) -> DatabaseChangeStream[_DocumentType]:
        """Watch changes on this database.

        Performs an aggregation with an implicit initial ``$changeStream``
        stage and returns a
        :class:`~pymongo.change_stream.DatabaseChangeStream` cursor which
        iterates over changes on all collections in this database.

        Introduced in MongoDB 4.0.

        .. code-block:: python

           with db.watch() as stream:
               for change in stream:
                   print(change)

        The :class:`~pymongo.change_stream.DatabaseChangeStream` iterable
        blocks until the next change document is returned or an error is
        raised. If the
        :meth:`~pymongo.change_stream.DatabaseChangeStream.next` method
        encounters a network error when retrieving a batch from the server,
        it will automatically attempt to recreate the cursor such that no
        change events are missed. Any error encountered during the resume
        attempt indicates there may be an outage and will be raised.

        .. code-block:: python

            try:
                with db.watch([{"$match": {"operationType": "insert"}}]) as stream:
                    for insert_change in stream:
                        print(insert_change)
            except pymongo.errors.PyMongoError:
                # The ChangeStream encountered an unrecoverable error or the
                # resume attempt failed to recreate the cursor.
                logging.error("...")

        For a precise description of the resume process see the
        `change streams specification`_.

        :param pipeline: A list of aggregation pipeline stages to
            append to an initial ``$changeStream`` stage. Not all
            pipeline stages are valid after a ``$changeStream`` stage, see the
            MongoDB documentation on change streams for the supported stages.
        :param full_document: The fullDocument to pass as an option