command_cursor – Tools for iterating over MongoDB command results

CommandCursor class to iterate over command results.

class pymongo.command_cursor.CommandCursor(collection, cursor_info, address, retrieved=0, batch_size=0, max_await_time_ms=None, session=None, explicit_session=False)

Create a new command cursor.

The parameter ‘retrieved’ is unused.

• property address

  The (host, port) of the server used, or None.

  New in version 3.0.

• property alive

  Does this cursor have the potential to return more data?

  Even if alive is True, next() can raise StopIteration. Best to use a for loop:

  for doc in collection.aggregate(pipeline):
      print(doc)

  Note

  alive can be True while iterating a cursor from a failed server. In this case alive will return False after next() fails to retrieve the next batch of results from the server.

• batch_size(batch_size)

  Limits the number of documents returned in one batch. Each batch requires a round trip to the server. It can be adjusted to optimize performance and limit data transfer.

  Note

  batch_size can not override MongoDB’s internal limits on the amount of data it will return to the client in a single batch (i.e if you set batch size to 1,000,000,000, MongoDB will currently only return 4-16MB of results per batch).

  Raises TypeError if batch_size is not an integer. Raises ValueError if batch_size is less than 0.

  • Parameters

    • batch_size: The size of each batch of results requested.

• close()

  Explicitly close / kill this cursor.

• property cursor_id

  Returns the id of the cursor.

• next()

  Advance the cursor.

• property session

  The cursor’s ClientSession, or None.

  New in version 3.6.

class pymongo.command_cursor.RawBatchCommandCursor(collection, cursor_info, address, retrieved=0, batch_size=0, max_await_time_ms=None, session=None, explicit_session=False)

Create a new cursor / iterator over raw batches of BSON data.

Should not be called directly by application developers - see aggregate_raw_batches() instead.

See also

The MongoDB documentation on cursors.