MotorCursor

class motor.motor_tornado.MotorCursor(cursor, collection)

Don’t construct a cursor yourself, but acquire one from methods like MotorCollection.find() or MotorCollection.aggregate().

Note

There is no need to manually close cursors; they are closed by the server after being fully iterated with to_list(), each(), or async for, or automatically closed by the client when the MotorCursor is cleaned up by the garbage collector.

add_option(mask: int) Cursor[_DocumentType]

Set arbitrary query flags using a bitmask.

To set the tailable flag: cursor.add_option(2)

allow_disk_use(allow_disk_use: bool) Cursor[_DocumentType]

Specifies whether MongoDB can use temporary disk files while processing a blocking sort operation.

Raises TypeError if allow_disk_use is not a boolean.

Note

allow_disk_use requires server version >= 4.4

Parameters:

allow_disk_use – if True, MongoDB may use temporary disk files to store data exceeding the system memory limit while processing a blocking sort operation.

clone()

Get a clone of this cursor.

async close()

Explicitly kill this cursor on the server.

Call like:

await cursor.close()
collation(collation: _CollationIn | None) Cursor[_DocumentType]

Adds a Collation to this query.

Raises TypeError if collation is not an instance of Collation or a dict. Raises InvalidOperation if this Cursor has already been used. Only the last collation applied to this cursor has any effect.

Parameters:

collation – An instance of Collation.

comment(comment: Any) Cursor[_DocumentType]

Adds a ‘comment’ to the cursor.

http://mongodb.com/docs/manual/reference/operator/comment/

Parameters:

comment – A string to attach to the query to help interpret and trace the operation in the server logs and in profile data.

coroutine distinct(key: str) list

Get a list of distinct values for key among all documents in the result set of this query.

Raises TypeError if key is not an instance of str.

The distinct() method obeys the read_preference of the Collection instance on which find() was called.

Parameters:

key – name of key for which we want to get the distinct values

each(callback)

Iterates over all the documents for this cursor.

each() returns immediately, and callback is executed asynchronously for each document. callback is passed (None, None) when iteration is complete.

Cancel iteration early by returning False from the callback. (Only False cancels iteration: returning None or 0 does not.)

>>> def each(result, error):
...     if error:
...         raise error
...     elif result:
...         sys.stdout.write(str(result["_id"]) + ", ")
...     else:
...         # Iteration complete
...         IOLoop.current().stop()
...         print("done")
...
>>> cursor = collection.find().sort([("_id", 1)])
>>> cursor.each(callback=each)
>>> IOLoop.current().start()
0, 1, 2, 3, 4, done

Note

Unlike other Motor methods, each requires a callback and does not return a Future, so it cannot be used in a coroutine. async for and to_list() are much easier to use.

Parameters:
  • callback: function taking (document, error)

coroutine explain() _DocumentType

Returns an explain plan record for this cursor.

Note

This method uses the default verbosity mode of the explain command, allPlansExecution. To use a different verbosity use command() to run the explain command directly.

See also

The MongoDB documentation on explain.

hint(index: str | Sequence[str | Tuple[str, int | str | Mapping[str, Any]]] | Mapping[str, Any] | None) Cursor[_DocumentType]

Adds a ‘hint’, telling Mongo the proper index to use for the query.

Judicious use of hints can greatly improve query performance. When doing a query on multiple fields (at least one of which is indexed) pass the indexed field as a hint to the query. Raises OperationFailure if the provided hint requires an index that does not exist on this collection, and raises InvalidOperation if this cursor has already been used.

index should be an index as passed to create_index() (e.g. [('field', ASCENDING)]) or the name of the index. If index is None any existing hint for this query is cleared. The last hint applied to this cursor takes precedence over all others.

Parameters:

index – index to hint on (as an index specifier)

limit(limit: int) Cursor[_DocumentType]

Limits the number of results to be returned by this cursor.

Raises TypeError if limit is not an integer. Raises InvalidOperation if this Cursor has already been used. The last limit applied to this cursor takes precedence. A limit of 0 is equivalent to no limit.

Parameters:

limit – the number of results to return

See also

The MongoDB documentation on limit.

max(spec: Sequence[str | Tuple[str, int | str | Mapping[str, Any]]] | Mapping[str, Any]) Cursor[_DocumentType]

Adds max operator that specifies upper bound for specific index.

When using max, hint() should also be configured to ensure the query uses the expected index and starting in MongoDB 4.2 hint() will be required.

Parameters:

spec – a list of field, limit pairs specifying the exclusive upper bound for all keys of a specific index in order.

max_await_time_ms(max_await_time_ms: int | None) Cursor[_DocumentType]

Specifies a time limit for a getMore operation on a TAILABLE_AWAIT cursor. For all other types of cursor max_await_time_ms is ignored.

Raises TypeError if max_await_time_ms is not an integer or None. Raises InvalidOperation if this Cursor has already been used.

Note

max_await_time_ms requires server version >= 3.2

Parameters:

max_await_time_ms – the time limit after which the operation is aborted

max_scan(max_scan: int | None) Cursor[_DocumentType]

DEPRECATED - Limit the number of documents to scan when performing the query.

Raises InvalidOperation if this cursor has already been used. Only the last max_scan() applied to this cursor has any effect.

Parameters:

max_scan – the maximum number of documents to scan

max_time_ms(max_time_ms: int | None) Cursor[_DocumentType]

Specifies a time limit for a query operation. If the specified time is exceeded, the operation will be aborted and ExecutionTimeout is raised. If max_time_ms is None no limit is applied.

Raises TypeError if max_time_ms is not an integer or None. Raises InvalidOperation if this Cursor has already been used.

Parameters:

max_time_ms – the time limit after which the operation is aborted

min(spec: Sequence[str | Tuple[str, int | str | Mapping[str, Any]]] | Mapping[str, Any]) Cursor[_DocumentType]

Adds min operator that specifies lower bound for specific index.

When using min, hint() should also be configured to ensure the query uses the expected index and starting in MongoDB 4.2 hint() will be required.

Parameters:

spec – a list of field, limit pairs specifying the inclusive lower bound for all keys of a specific index in order.

async next()

Advance the cursor.

Added in version 2.2.

next_object()

DEPRECATED - Get a document from the most recently fetched batch, or None. See fetch_next.

The next_object() method is deprecated and may be removed in a future major release. Use async for to elegantly iterate over MotorCursor objects instead.

Changed in version 2.2: Deprecated.

remove_option(mask: int) Cursor[_DocumentType]

Unset arbitrary query flags using a bitmask.

To unset the tailable flag: cursor.remove_option(2)

rewind()

Rewind this cursor to its unevaluated state.

skip(skip: int) Cursor[_DocumentType]

Skips the first skip results of this cursor.

Raises TypeError if skip is not an integer. Raises ValueError if skip is less than 0. Raises InvalidOperation if this Cursor has already been used. The last skip applied to this cursor takes precedence.

Parameters:

skip – the number of results to skip

sort(key_or_list: str | Sequence[str | Tuple[str, int | str | Mapping[str, Any]]] | Mapping[str, Any], direction: int | str | None = None) Cursor[_DocumentType]

Sorts this cursor’s results.

Pass a field name and a direction, either ASCENDING or DESCENDING:

>>> async def f():
...     cursor = collection.find().sort("_id", pymongo.DESCENDING)
...     docs = await cursor.to_list(None)
...     print([d["_id"] for d in docs])
...
>>> IOLoop.current().run_sync(f)
[4, 3, 2, 1, 0]

To sort by multiple fields, pass a list of (key, direction) pairs:

>>> async def f():
...     cursor = collection.find().sort(
...         [("field1", pymongo.ASCENDING), ("field2", pymongo.DESCENDING)]
...     )
...     docs = await cursor.to_list(None)
...     print([(d["field1"], d["field2"]) for d in docs])
...
>>> IOLoop.current().run_sync(f)
[(0, 4), (0, 2), (0, 0), (1, 3), (1, 1)]

Text search results can be sorted by relevance:

>>> async def f():
...     cursor = collection.find(
...         {"$text": {"$search": "some words"}}, {"score": {"$meta": "textScore"}}
...     )
...     # Sort by 'score' field.
...     cursor.sort([("score", {"$meta": "textScore"})])
...     async for doc in cursor:
...         print("%.1f %s" % (doc["score"], doc["field"]))
...
>>> IOLoop.current().run_sync(f)
1.5 words about some words
1.0 words

Raises InvalidOperation if this cursor has already been used. Only the last sort() applied to this cursor has any effect.

Parameters:
  • key_or_list: a single key or a list of (key, direction) pairs specifying the keys to sort on

  • direction (optional): only used if key_or_list is a single key, if not given ASCENDING is assumed

coroutine to_list(length)

Get a list of documents.

>>> from motor.motor_tornado import MotorClient
>>> collection = MotorClient().test.test_collection
>>>
>>> async def f():
...     cursor = collection.find().sort([("_id", 1)])
...     docs = await cursor.to_list(length=2)
...     while docs:
...         print(docs)
...         docs = await cursor.to_list(length=2)
...     print("done")
...
>>> ioloop.IOLoop.current().run_sync(f)
[{'_id': 0}, {'_id': 1}]
[{'_id': 2}, {'_id': 3}]
done
Parameters:
  • length: maximum number of documents to return for this call, or None

Returns a Future.

Changed in version 2.0: No longer accepts a callback argument.

Changed in version 0.2: callback must be passed as a keyword argument, like to_list(10, callback=callback), and the length parameter is no longer optional.

where(code: str | Code) Cursor[_DocumentType]

Adds a $where clause to this query.

The code argument must be an instance of str Code containing a JavaScript expression. This expression will be evaluated for each document scanned. Only those documents for which the expression evaluates to true will be returned as results. The keyword this refers to the object currently being scanned. For example:

# Find all documents where field "a" is less than "b" plus "c".
async for doc in db.test.find().where('this.a < (this.b + this.c)'):
    print(doc)

Raises TypeError if code is not an instance of str. Raises InvalidOperation if this MotorCursor has already been used. Only the last call to where() applied to a MotorCursor has any effect.

Note

MongoDB 4.4 drops support for Code with scope variables. Consider using $expr instead.

Parameters:
  • code: JavaScript expression to use as a filter

property address

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

Changed in version 3.0: Renamed from “conn_id”.

property alive

Does this cursor have the potential to return more data?

This is mostly useful with tailable cursors since they will stop iterating even though they may return more results in the future.

With regular cursors, simply use a for loop instead of alive:

for doc in collection.find():
    print(doc)

Note

Even if alive is True, next() can raise StopIteration. alive can also 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.

property cursor_id

Returns the id of the cursor

Added in version 2.2.

property fetch_next

DEPRECATED - A Future used with gen.coroutine to asynchronously retrieve the next document in the result set, fetching a batch of documents from the server if necessary. Resolves to False if there are no more documents, otherwise next_object() is guaranteed to return a document:

Attention

The fetch_next property is deprecated and will be removed in Motor 3.0. Use async for to iterate elegantly and efficiently over MotorCursor objects instead.:

>>> async def f():
...     await collection.drop()
...     await collection.insert_many([{"_id": i} for i in range(5)])
...     async for doc in collection.find():
...         sys.stdout.write(str(doc["_id"]) + ", ")
...     print("done")
...
>>> IOLoop.current().run_sync(f)
0, 1, 2, 3, 4, done

While it appears that fetch_next retrieves each document from the server individually, the cursor actually fetches documents efficiently in large batches. Example usage:

>>> async def f():
...     await collection.drop()
...     await collection.insert_many([{"_id": i} for i in range(5)])
...     cursor = collection.find().sort([("_id", 1)])
...     while await cursor.fetch_next:
...         doc = cursor.next_object()
...         sys.stdout.write(str(doc["_id"]) + ", ")
...     print("done")
...
>>> IOLoop.current().run_sync(f)
0, 1, 2, 3, 4, done

Changed in version 2.2: Deprecated.

property session

The cursor’s ClientSession, or None.

Added in version 3.6.

MotorCommandCursor

class motor.motor_tornado.MotorCommandCursor(cursor, collection)

Don’t construct a cursor yourself, but acquire one from methods like MotorCollection.find() or MotorCollection.aggregate().

Note

There is no need to manually close cursors; they are closed by the server after being fully iterated with to_list(), each(), or async for, or automatically closed by the client when the MotorCursor is cleaned up by the garbage collector.

async close()

Explicitly kill this cursor on the server.

Call like:

await cursor.close()
each(callback)

Iterates over all the documents for this cursor.

each() returns immediately, and callback is executed asynchronously for each document. callback is passed (None, None) when iteration is complete.

Cancel iteration early by returning False from the callback. (Only False cancels iteration: returning None or 0 does not.)

>>> def each(result, error):
...     if error:
...         raise error
...     elif result:
...         sys.stdout.write(str(result["_id"]) + ", ")
...     else:
...         # Iteration complete
...         IOLoop.current().stop()
...         print("done")
...
>>> cursor = collection.find().sort([("_id", 1)])
>>> cursor.each(callback=each)
>>> IOLoop.current().start()
0, 1, 2, 3, 4, done

Note

Unlike other Motor methods, each requires a callback and does not return a Future, so it cannot be used in a coroutine. async for and to_list() are much easier to use.

Parameters:
  • callback: function taking (document, error)

async next()

Advance the cursor.

Added in version 2.2.

next_object()

DEPRECATED - Get a document from the most recently fetched batch, or None. See fetch_next.

The next_object() method is deprecated and may be removed in a future major release. Use async for to elegantly iterate over MotorCursor objects instead.

Changed in version 2.2: Deprecated.

coroutine to_list(length)

Get a list of documents.

>>> from motor.motor_tornado import MotorClient
>>> collection = MotorClient().test.test_collection
>>>
>>> async def f():
...     cursor = collection.find().sort([("_id", 1)])
...     docs = await cursor.to_list(length=2)
...     while docs:
...         print(docs)
...         docs = await cursor.to_list(length=2)
...     print("done")
...
>>> ioloop.IOLoop.current().run_sync(f)
[{'_id': 0}, {'_id': 1}]
[{'_id': 2}, {'_id': 3}]
done
Parameters:
  • length: maximum number of documents to return for this call, or None

Returns a Future.

Changed in version 2.0: No longer accepts a callback argument.

Changed in version 0.2: callback must be passed as a keyword argument, like to_list(10, callback=callback), and the length parameter is no longer optional.

async try_next()

Advance the cursor without blocking indefinitely.

This method returns the next document without waiting indefinitely for data.

If no document is cached locally then this method runs a single getMore command. If the getMore yields any documents, the next document is returned, otherwise, if the getMore returns no documents (because there is no additional data) then None is returned.

Returns:

The next document or None when no document is available after running a single getMore or when the cursor is closed.

property address

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

Added 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.

property cursor_id

Returns the id of the cursor.

property fetch_next

DEPRECATED - A Future used with gen.coroutine to asynchronously retrieve the next document in the result set, fetching a batch of documents from the server if necessary. Resolves to False if there are no more documents, otherwise next_object() is guaranteed to return a document:

Attention

The fetch_next property is deprecated and will be removed in Motor 3.0. Use async for to iterate elegantly and efficiently over MotorCursor objects instead.:

>>> async def f():
...     await collection.drop()
...     await collection.insert_many([{"_id": i} for i in range(5)])
...     async for doc in collection.find():
...         sys.stdout.write(str(doc["_id"]) + ", ")
...     print("done")
...
>>> IOLoop.current().run_sync(f)
0, 1, 2, 3, 4, done

While it appears that fetch_next retrieves each document from the server individually, the cursor actually fetches documents efficiently in large batches. Example usage:

>>> async def f():
...     await collection.drop()
...     await collection.insert_many([{"_id": i} for i in range(5)])
...     cursor = collection.find().sort([("_id", 1)])
...     while await cursor.fetch_next:
...         doc = cursor.next_object()
...         sys.stdout.write(str(doc["_id"]) + ", ")
...     print("done")
...
>>> IOLoop.current().run_sync(f)
0, 1, 2, 3, 4, done

Changed in version 2.2: Deprecated.

property session

The cursor’s ClientSession, or None.

Added in version 3.6.