Python操作Mongodb (增刪改查）
阿新 • • 發佈：2018-12-23
find(self, *args, **kwargs) method of pymongo.collection.Collection instance
Query the database.
The `filter` argument is a prototype document that all results
must match. For example:
>>> db.test.find({"hello": "world"})
only matches documents that have a key "hello" with value
"world". Matches can have other keys *in addition* to
"hello". The `projection` argument is used to specify a subset
of fields that should be included in the result documents. By
limiting results to a certain subset of fields you can cut
down on network traffic and decoding time.
Raises :class:`TypeError` if any of the arguments are of improper type. Returns an instance of :class:`~pymongo.cursor.Cursor` corresponding to this query. The :meth:`find` method obeys the :attr:`read_preference` of this :class:`Collection`. :Parameters: - `filter` (optional): a SON object specifying elements which must be present for a document to be included in the result set - `projection` (optional): a list of field names that should be returned in the result set or a dict specifying the fields to include or exclude. If `projection` is a list "_id" will always be returned. Use a dict to exclude fields from the result (e.g. projection={'_id': False}). - `skip` (optional): the number of documents to omit (from the start of the result set) when returning the results - `limit` (optional): the maximum number of results to return - `no_cursor_timeout` (optional): if False (the default), any returned cursor is closed by the server after 10 minutes of inactivity. If set to True, the returned cursor will never time out on the server. Care should be taken to ensure that cursors with no_cursor_timeout turned on are properly closed. - `cursor_type` (optional): the type of cursor to return. The valid options are defined by :class:`~pymongo.cursor.CursorType`: - :attr:`~pymongo.cursor.CursorType.NON_TAILABLE` - the result of this find call will return a standard cursor over the result set. - :attr:`~pymongo.cursor.CursorType.TAILABLE` - the result of this find call will be a tailable cursor - tailable cursors are only for use with capped collections. They are not closed when the last data is retrieved but are kept open and the cursor location marks the final document position. If more data is received iteration of the cursor will continue from the last document received. For details, see the `tailable cursor documentation <http://www.mongodb.org/display/DOCS/Tailable+Cursors>`_. - :attr:`~pymongo.cursor.CursorType.TAILABLE_AWAIT` - the result of this find call will be a tailable cursor with the await flag set. The server will wait for a few seconds after returning the full result set so that it can capture and return additional data added during the query. - :attr:`~pymongo.cursor.CursorType.EXHAUST` - the result of this find call will be an exhaust cursor. MongoDB will stream batched results to the client without waiting for the client to request each batch, reducing latency. See notes on compatibility below. - `sort` (optional): a list of (key, direction) pairs specifying the sort order for this query. See :meth:`~pymongo.cursor.Cursor.sort` for details. - `allow_partial_results` (optional): if True, mongos will return partial results if some shards are down instead of returning an error. - `oplog_replay` (optional): If True, set the oplogReplay query flag. - `modifiers` (optional): A dict specifying the MongoDB `query modifiers`_ that should be used for this query. For example:: >>> db.test.find(modifiers={"$maxTimeMS": 500}) - `batch_size` (optional): Limits the number of documents returned in a single batch. - `manipulate` (optional): **DEPRECATED** - If True (the default), apply any outgoing SON manipulators before returning. - `collation` (optional): An instance of :class:`~pymongo.collation.Collation`. This option is only supported on MongoDB 3.4 and above. .. note:: There are a number of caveats to using :attr:`~pymongo.cursor.CursorType.EXHAUST` as cursor_type: - The `limit` option can not be used with an exhaust cursor. - Exhaust cursors are not supported by mongos and can not be used with a sharded cluster. The :meth:`find` method obeys the :attr:`read_preference` of this :class:`Collection`. :Parameters: - `filter` (optional): a SON object specifying elements which must be present for a document to be included in the result set - `projection` (optional): a list of field names that should be returned in the result set or a dict specifying the fields to include or exclude. If `projection` is a list "_id" will always be returned. Use a dict to exclude fields from the result (e.g. projection={'_id': False}). - `skip` (optional): the number of documents to omit (from the start of the result set) when returning the results - `limit` (optional): the maximum number of results to return - `no_cursor_timeout` (optional): if False (the default), any returned cursor is closed by the server after 10 minutes of inactivity. If set to True, the returned cursor will never time out on the server. Care should be taken to ensure that cursors with no_cursor_timeout turned on are properly closed. - `cursor_type` (optional): the type of cursor to return. The valid options are defined by :class:`~pymongo.cursor.CursorType`: - :attr:`~pymongo.cursor.CursorType.NON_TAILABLE` - the result of this find call will return a standard cursor over the result set. - :attr:`~pymongo.cursor.CursorType.TAILABLE` - the result of this find call will be a tailable cursor - tailable cursors are only for use with capped collections. They are not closed when the last data is retrieved but are kept open and the cursor location marks the final document position. If more data is received iteration of the cursor will continue from the last document received. For details, see the `tailable cursor documentation <http://www.mongodb.org/display/DOCS/Tailable+Cursors>`_. - :attr:`~pymongo.cursor.CursorType.TAILABLE_AWAIT` - the result of this find call will be a tailable cursor with the await flag set. The server will wait for a few seconds after returning the full result set so that it can capture and return additional data added during the query. - :attr:`~pymongo.cursor.CursorType.EXHAUST` - the result of this find call will be an exhaust cursor. MongoDB will stream batched results to the client without waiting for the client to request each batch, reducing latency. See notes on compatibility below. - `sort` (optional): a list of (key, direction) pairs specifying the sort order for this query. See :meth:`~pymongo.cursor.Cursor.sort` for details. - `allow_partial_results` (optional): if True, mongos will return partial results if some shards are down instead of returning an error. - `oplog_replay` (optional): If True, set the oplogReplay query flag. - `modifiers` (optional): A dict specifying the MongoDB `query modifiers`_ that should be used for this query. For example:: >>> db.test.find(modifiers={"$maxTimeMS": 500}) - `batch_size` (optional): Limits the number of documents returned in a single batch. - `manipulate` (optional): **DEPRECATED** - If True (the default), apply any outgoing SON manipulators before returning. - `collation` (optional): An instance of :class:`~pymongo.collation.Collation`. This option is only supported on MongoDB 3.4 and above.
Raises :class:`TypeError` if any of the arguments are of improper type. Returns an instance of :class:`~pymongo.cursor.Cursor` corresponding to this query. The :meth:`find` method obeys the :attr:`read_preference` of this :class:`Collection`. :Parameters: - `filter` (optional): a SON object specifying elements which must be present for a document to be included in the result set - `projection` (optional): a list of field names that should be returned in the result set or a dict specifying the fields to include or exclude. If `projection` is a list "_id" will always be returned. Use a dict to exclude fields from the result (e.g. projection={'_id': False}). - `skip` (optional): the number of documents to omit (from the start of the result set) when returning the results - `limit` (optional): the maximum number of results to return - `no_cursor_timeout` (optional): if False (the default), any returned cursor is closed by the server after 10 minutes of inactivity. If set to True, the returned cursor will never time out on the server. Care should be taken to ensure that cursors with no_cursor_timeout turned on are properly closed. - `cursor_type` (optional): the type of cursor to return. The valid options are defined by :class:`~pymongo.cursor.CursorType`: - :attr:`~pymongo.cursor.CursorType.NON_TAILABLE` - the result of this find call will return a standard cursor over the result set. - :attr:`~pymongo.cursor.CursorType.TAILABLE` - the result of this find call will be a tailable cursor - tailable cursors are only for use with capped collections. They are not closed when the last data is retrieved but are kept open and the cursor location marks the final document position. If more data is received iteration of the cursor will continue from the last document received. For details, see the `tailable cursor documentation <http://www.mongodb.org/display/DOCS/Tailable+Cursors>`_. - :attr:`~pymongo.cursor.CursorType.TAILABLE_AWAIT` - the result of this find call will be a tailable cursor with the await flag set. The server will wait for a few seconds after returning the full result set so that it can capture and return additional data added during the query. - :attr:`~pymongo.cursor.CursorType.EXHAUST` - the result of this find call will be an exhaust cursor. MongoDB will stream batched results to the client without waiting for the client to request each batch, reducing latency. See notes on compatibility below. - `sort` (optional): a list of (key, direction) pairs specifying the sort order for this query. See :meth:`~pymongo.cursor.Cursor.sort` for details. - `allow_partial_results` (optional): if True, mongos will return partial results if some shards are down instead of returning an error. - `oplog_replay` (optional): If True, set the oplogReplay query flag. - `modifiers` (optional): A dict specifying the MongoDB `query modifiers`_ that should be used for this query. For example:: >>> db.test.find(modifiers={"$maxTimeMS": 500}) - `batch_size` (optional): Limits the number of documents returned in a single batch. - `manipulate` (optional): **DEPRECATED** - If True (the default), apply any outgoing SON manipulators before returning. - `collation` (optional): An instance of :class:`~pymongo.collation.Collation`. This option is only supported on MongoDB 3.4 and above. .. note:: There are a number of caveats to using :attr:`~pymongo.cursor.CursorType.EXHAUST` as cursor_type: - The `limit` option can not be used with an exhaust cursor. - Exhaust cursors are not supported by mongos and can not be used with a sharded cluster. The :meth:`find` method obeys the :attr:`read_preference` of this :class:`Collection`. :Parameters: - `filter` (optional): a SON object specifying elements which must be present for a document to be included in the result set - `projection` (optional): a list of field names that should be returned in the result set or a dict specifying the fields to include or exclude. If `projection` is a list "_id" will always be returned. Use a dict to exclude fields from the result (e.g. projection={'_id': False}). - `skip` (optional): the number of documents to omit (from the start of the result set) when returning the results - `limit` (optional): the maximum number of results to return - `no_cursor_timeout` (optional): if False (the default), any returned cursor is closed by the server after 10 minutes of inactivity. If set to True, the returned cursor will never time out on the server. Care should be taken to ensure that cursors with no_cursor_timeout turned on are properly closed. - `cursor_type` (optional): the type of cursor to return. The valid options are defined by :class:`~pymongo.cursor.CursorType`: - :attr:`~pymongo.cursor.CursorType.NON_TAILABLE` - the result of this find call will return a standard cursor over the result set. - :attr:`~pymongo.cursor.CursorType.TAILABLE` - the result of this find call will be a tailable cursor - tailable cursors are only for use with capped collections. They are not closed when the last data is retrieved but are kept open and the cursor location marks the final document position. If more data is received iteration of the cursor will continue from the last document received. For details, see the `tailable cursor documentation <http://www.mongodb.org/display/DOCS/Tailable+Cursors>`_. - :attr:`~pymongo.cursor.CursorType.TAILABLE_AWAIT` - the result of this find call will be a tailable cursor with the await flag set. The server will wait for a few seconds after returning the full result set so that it can capture and return additional data added during the query. - :attr:`~pymongo.cursor.CursorType.EXHAUST` - the result of this find call will be an exhaust cursor. MongoDB will stream batched results to the client without waiting for the client to request each batch, reducing latency. See notes on compatibility below. - `sort` (optional): a list of (key, direction) pairs specifying the sort order for this query. See :meth:`~pymongo.cursor.Cursor.sort` for details. - `allow_partial_results` (optional): if True, mongos will return partial results if some shards are down instead of returning an error. - `oplog_replay` (optional): If True, set the oplogReplay query flag. - `modifiers` (optional): A dict specifying the MongoDB `query modifiers`_ that should be used for this query. For example:: >>> db.test.find(modifiers={"$maxTimeMS": 500}) - `batch_size` (optional): Limits the number of documents returned in a single batch. - `manipulate` (optional): **DEPRECATED** - If True (the default), apply any outgoing SON manipulators before returning. - `collation` (optional): An instance of :class:`~pymongo.collation.Collation`. This option is only supported on MongoDB 3.4 and above.