mongo_client
– Tools for connecting to MongoDB¶
Tools for connecting to MongoDB.
See also
Module master_slave_connection
for
connecting to master-slave clusters, and
High Availability and PyMongo for an example of how to connect
to a replica set, or specify a list of mongos instances for automatic
failover.
To get a Database
instance from a
MongoClient
use either dictionary-style or attribute-style
access:
>>> from pymongo import MongoClient
>>> c = MongoClient()
>>> c.test_database
Database(MongoClient('localhost', 27017), u'test_database')
>>> c['test-database']
Database(MongoClient('localhost', 27017), u'test-database')
-
class
pymongo.mongo_client.
MongoClient
([host='localhost'[, port=27017[, max_pool_size=100[, document_class=dict[, tz_aware=False[, **kwargs]]]]]])¶ Create a new connection to a single MongoDB instance at host:port.
The resultant client object has connection-pooling built in. It also performs auto-reconnection when necessary. If an operation fails because of a connection error,
ConnectionFailure
is raised. If auto-reconnection will be performed,AutoReconnect
will be raised. Application code should handle this exception (recognizing that the operation failed) and then continue to execute.Raises
TypeError
if port is not an instance ofint
. RaisesConnectionFailure
if the connection cannot be made.The host parameter can be a full mongodb URI, in addition to a simple hostname. It can also be a list of hostnames or URIs. Any port specified in the host string(s) will override the port parameter. If multiple mongodb URIs containing database or auth information are passed, the last database, username, and password present will be used. For username and passwords reserved characters like ‘:’, ‘/’, ‘+’ and ‘@’ must be escaped following RFC 2396.
Parameters: - host (optional): hostname or IP address of the instance to connect to, or a mongodb URI, or a list of hostnames / mongodb URIs. If host is an IPv6 literal it must be enclosed in ‘[‘ and ‘]’ characters following the RFC2732 URL syntax (e.g. ‘[::1]’ for localhost)
- port (optional): port number on which to connect
- max_pool_size (optional): The maximum number of connections that the pool will open simultaneously. If this is set, operations will block if there are max_pool_size outstanding connections from the pool. Defaults to 100.
- document_class (optional): default class to use for documents returned from queries on this client
- tz_aware (optional): if
True
,datetime
instances returned as values in a document by thisMongoClient
will be timezone aware (otherwise they will be naive)
Other optional parameters can be passed as keyword arguments:- socketTimeoutMS: (integer) How long (in milliseconds) a send or
receive on a socket can take before timing out. Defaults to
None
(no timeout). - connectTimeoutMS: (integer) How long (in milliseconds) a
connection can take to be opened before timing out. Defaults to
20000
. - waitQueueTimeoutMS: (integer) How long (in milliseconds) a
thread will wait for a socket from the pool if the pool has no
free sockets. Defaults to
None
(no timeout). - waitQueueMultiple: (integer) Multiplied by max_pool_size to give
the number of threads allowed to wait for a socket at one time.
Defaults to
None
(no waiters). - auto_start_request: If
True
, each thread that accesses thisMongoClient
has a socket allocated to it for the thread’s lifetime. This ensures consistent reads, even if you read after an unacknowledged write. Defaults toFalse
- use_greenlets: If
True
,start_request()
will ensure that the current greenlet uses the same socket for all operations untilend_request()
Write Concern options:- w: (integer or string) If this is a replica set, write operations will block until they have been replicated to the specified number or tagged set of servers. w=<int> always includes the replica set primary (e.g. w=3 means write to the primary and wait until replicated to two secondaries). Passing w=0 disables write acknowledgement and all other write concern options.
- wtimeout: (integer) Used in conjunction with w. Specify a value in milliseconds to control how long to wait for write propagation to complete. If replication does not complete in the given timeframe, a timeout exception is raised.
- j: If
True
block until write operations have been committed to the journal. Cannot be used in combination with fsync. Prior to MongoDB 2.6 this option was ignored if the server was running without journaling. Starting with MongoDB 2.6 write operations will fail with an exception if this option is used when the server is running without journaling. - fsync: If
True
and the server is running without journaling, blocks until the server has synced all data files to disk. If the server is running with journaling, this acts the same as the j option, blocking until write operations have been committed to the journal. Cannot be used in combination with j.
Replica set keyword arguments for connecting with a replica set - either directly or via a mongos:(ignored by standalone mongod instances)- replicaSet: (string) The name of the replica set to connect to. The driver will verify that the replica set it connects to matches this name. Implies that the hosts specified are a seed list and the driver should attempt to find all members of the set. Ignored by mongos.
- read_preference: The read preference for this client. If
connecting to a secondary then a read preference mode other than
PRIMARY is required - otherwise all queries will throw
AutoReconnect
“not master”. SeeReadPreference
for all available read preference options. - tag_sets: Ignored unless connecting to a replica set via mongos.
Specify a priority-order for tag sets, provide a list of
tag sets:
[{'dc': 'ny'}, {'dc': 'la'}, {}]
. A final, empty tag set,{}
, means “read from any member that matches the mode, ignoring tags.
SSL configuration:- ssl: If
True
, create the connection to the server using SSL. - ssl_keyfile: The private keyfile used to identify the local
connection against mongod. If included with the
certfile
then only thessl_certfile
is needed. Impliesssl=True
. - ssl_certfile: The certificate file used to identify the local
connection against mongod. Implies
ssl=True
. - ssl_cert_reqs: Specifies whether a certificate is required from
the other side of the connection, and whether it will be validated
if provided. It must be one of the three values
ssl.CERT_NONE
(certificates ignored),ssl.CERT_OPTIONAL
(not required, but validated if provided), orssl.CERT_REQUIRED
(required and validated). If the value of this parameter is notssl.CERT_NONE
, then thessl_ca_certs
parameter must point to a file of CA certificates. Impliesssl=True
. - ssl_ca_certs: The ca_certs file contains a set of concatenated
“certification authority” certificates, which are used to validate
certificates passed from the other end of the connection.
Implies
ssl=True
.
See also
Changed in version 2.5: Added additional ssl options
New in version 2.4.
-
disconnect
()¶ Disconnect from MongoDB.
Disconnecting will close all underlying sockets in the connection pool. If this instance is used again it will be automatically re-opened. Care should be taken to make sure that
disconnect()
is not called in the middle of a sequence of operations in which ordering is important. This could lead to unexpected results.See also
New in version 1.3.
-
close
()¶ Alias for
disconnect()
Disconnecting will close all underlying sockets in the connection pool. If this instance is used again it will be automatically re-opened. Care should be taken to make sure that
disconnect()
is not called in the middle of a sequence of operations in which ordering is important. This could lead to unexpected results.See also
New in version 2.1.
-
alive
()¶ Return
False
if there has been an error communicating with the server, elseTrue
.This method attempts to check the status of the server with minimal I/O. The current thread / greenlet retrieves a socket from the pool (its request socket if it’s in a request, or a random idle socket if it’s not in a request) and checks whether calling select on it raises an error. If there are currently no idle sockets,
alive()
will attempt to actually connect to the server.A more certain way to determine server availability is:
client.admin.command('ping')
-
c[db_name] || c.db_name
Get the db_name
Database
onMongoClient
c.Raises
InvalidName
if an invalid database name is used.
-
host
¶ Current connected host.
Changed in version 1.3:
host
is now a property rather than a method.
-
port
¶ Current connected port.
Changed in version 1.3:
port
is now a property rather than a method.
-
is_primary
¶ If this instance is connected to a standalone, a replica set primary, or the master of a master-slave set.
New in version 2.3.
-
is_mongos
¶ If this instance is connected to mongos.
New in version 2.3.
-
max_pool_size
¶ The maximum number of sockets the pool will open concurrently.
When the pool has reached max_pool_size, operations block waiting for a socket to be returned to the pool. If
waitQueueTimeoutMS
is set, a blocked operation will raiseConnectionFailure
after a timeout. By defaultwaitQueueTimeoutMS
is not set.Warning
SIGNIFICANT BEHAVIOR CHANGE in 2.6. Previously, this parameter would limit only the idle sockets the pool would hold onto, not the number of open sockets. The default has also changed to 100.
Changed in version 2.6.
New in version 1.11.
-
nodes
¶ List of all known nodes.
Nodes are either specified when this instance was created, or discovered through the replica set discovery mechanism.
New in version 1.8.
-
auto_start_request
¶ Is auto_start_request enabled?
-
document_class
¶ Default class to use for documents returned from this client.
New in version 1.7.
-
tz_aware
¶ Does this client return timezone-aware datetimes?
New in version 1.8.
-
max_bson_size
¶ Return the maximum size BSON object the connected server accepts in bytes. Defaults to 16MB if not connected to a server.
New in version 1.10.
-
max_message_size
¶ Return the maximum message size the connected server accepts in bytes. Defaults to 32MB if not connected to a server.
New in version 2.6.
-
min_wire_version
¶ The minWireVersion reported by the server.
Returns
0
when connected to server versions prior to MongoDB 2.6.New in version 2.7.
-
max_wire_version
¶ The maxWireVersion reported by the server.
Returns
0
when connected to server versions prior to MongoDB 2.6.New in version 2.7.
-
read_preference
¶ The read preference mode for this instance.
See
ReadPreference
for available options.New in version 2.1.
-
tag_sets
¶ Set
tag_sets
to a list of dictionaries like [{‘dc’: ‘ny’}] to read only from members whosedc
tag has the value"ny"
. To specify a priority-order for tag sets, provide a list of tag sets:[{'dc': 'ny'}, {'dc': 'la'}, {}]
. A final, empty tag set,{}
, means “read from any member that matches the mode, ignoring tags.” ReplicaSetConnection tries each set of tags in turn until it finds a set of tags with at least one matching member.See also
New in version 2.3.
-
secondary_acceptable_latency_ms
¶ Any replica-set member whose ping time is within secondary_acceptable_latency_ms of the nearest member may accept reads. Defaults to 15 milliseconds.
See
ReadPreference
.New in version 2.3.
Note
secondary_acceptable_latency_ms
is ignored when talking to a replica set through a mongos. The equivalent is the localThreshold command line option.
-
write_concern
¶ The default write concern for this instance.
Supports dict style access for getting/setting write concern options. Valid options include:
- w: (integer or string) If this is a replica set, write operations will block until they have been replicated to the specified number or tagged set of servers. w=<int> always includes the replica set primary (e.g. w=3 means write to the primary and wait until replicated to two secondaries). Setting w=0 disables write acknowledgement and all other write concern options.
- wtimeout: (integer) Used in conjunction with w. Specify a value in milliseconds to control how long to wait for write propagation to complete. If replication does not complete in the given timeframe, a timeout exception is raised.
- j: If
True
block until write operations have been committed to the journal. Cannot be used in combination with fsync. Prior to MongoDB 2.6 this option was ignored if the server was running without journaling. Starting with MongoDB 2.6 write operations will fail with an exception if this option is used when the server is running without journaling. - fsync: If
True
and the server is running without journaling, blocks until the server has synced all data files to disk. If the server is running with journaling, this acts the same as the j option, blocking until write operations have been committed to the journal. Cannot be used in combination with j.
>>> m = pymongo.MongoClient() >>> m.write_concern {} >>> m.write_concern = {'w': 2, 'wtimeout': 1000} >>> m.write_concern {'wtimeout': 1000, 'w': 2} >>> m.write_concern['j'] = True >>> m.write_concern {'wtimeout': 1000, 'j': True, 'w': 2} >>> m.write_concern = {'j': True} >>> m.write_concern {'j': True} >>> # Disable write acknowledgement and write concern ... >>> m.write_concern['w'] = 0
Note
Accessing
write_concern
returns its value (a subclass ofdict
), not a copy.Warning
If you are using
Connection
orReplicaSetConnection
make sure you explicitly setw
to 1 (or a greater value) orsafe
toTrue
. Unlike callingset_lasterror_options()
, setting an option inwrite_concern
does not implicitly setsafe
toTrue
.
-
uuid_subtype
¶ This attribute specifies which BSON Binary subtype is used when storing UUIDs. Historically UUIDs have been stored as BSON Binary subtype 3. This attribute is used to switch to the newer BSON Binary subtype 4. It can also be used to force legacy byte order and subtype compatibility with the Java and C# drivers. See the
bson.binary
module for all options.
-
is_locked
¶ Is this server locked? While locked, all write operations are blocked, although read operations may still be allowed. Use
unlock()
to unlock.New in version 2.0.
-
database_names
()¶ Get a list of the names of all databases on the connected server.
-
drop_database
(name_or_database)¶ Drop a database.
Raises
TypeError
if name_or_database is not an instance ofbasestring
(str
in python 3) or Database.Parameters: - name_or_database: the name of a database to drop, or a
Database
instance representing the database to drop
- name_or_database: the name of a database to drop, or a
-
copy_database
(from_name, to_name[, from_host=None[, username=None[, password=None]]])¶ Copy a database, potentially from another host.
Raises
TypeError
if from_name or to_name is not an instance ofbasestring
(str
in python 3). RaisesInvalidName
if to_name is not a valid database name.If from_host is
None
the current host is used as the source. Otherwise the database is copied from from_host.If the source database requires authentication, username and password must be specified.
Parameters: - from_name: the name of the source database
- to_name: the name of the target database
- from_host (optional): host name to copy from
- username (optional): username for source database
- password (optional): password for source database
Note
Specifying username and password requires server version >= 1.3.3+.
New in version 1.5.
-
get_default_database
()¶ Get the database named in the MongoDB connection URI.
>>> uri = 'mongodb://host/my_database' >>> client = MongoClient(uri) >>> db = client.get_default_database() >>> assert db.name == 'my_database'
Useful in scripts where you want to choose which database to use based only on the URI in a configuration file.
-
server_info
()¶ Get information about the MongoDB server we’re connected to.
-
start_request
()¶ Ensure the current thread or greenlet always uses the same socket until it calls
end_request()
. This ensures consistent reads, even if you read after an unacknowledged write.In Python 2.6 and above, or in Python 2.5 with “from __future__ import with_statement”,
start_request()
can be used as a context manager:>>> client = pymongo.MongoClient(auto_start_request=False) >>> db = client.test >>> _id = db.test_collection.insert({}) >>> with client.start_request(): ... for i in range(100): ... db.test_collection.update({'_id': _id}, {'$set': {'i':i}}) ... ... # Definitely read the document after the final update completes ... print db.test_collection.find({'_id': _id})
If a thread or greenlet calls start_request multiple times, an equal number of calls to
end_request()
is required to end the request.Changed in version 2.4: Now counts the number of calls to start_request and doesn’t end request until an equal number of calls to end_request.
New in version 2.2: The
Request
return value.start_request()
previously returned None
-
end_request
()¶ Undo
start_request()
. Ifend_request()
is called as many times asstart_request()
, the request is over and this thread’s connection returns to the pool. Extra calls toend_request()
have no effect.Ending a request allows the
socket
that has been reserved for this thread bystart_request()
to be returned to the pool. Other threads will then be able to re-use thatsocket
. If your application uses many threads, or has long-running threads that infrequently perform MongoDB operations, then judicious use of this method can lead to performance gains. Care should be taken, however, to make sure thatend_request()
is not called in the middle of a sequence of operations in which ordering is important. This could lead to unexpected results.
-
close_cursor
(cursor_id)¶ Close a single database cursor.
Raises
TypeError
if cursor_id is not an instance of(int, long)
. What closing the cursor actually means depends on this client’s cursor manager.Parameters: - cursor_id: id of cursor to close
-
kill_cursors
(cursor_ids)¶ Send a kill cursors message with the given ids.
Raises
TypeError
if cursor_ids is not an instance oflist
.Parameters: - cursor_ids: list of cursor ids to kill
-
set_cursor_manager
(manager_class)¶ Set this client’s cursor manager.
Raises
TypeError
if manager_class is not a subclass ofCursorManager
. A cursor manager handles closing cursors. Different managers can implement different policies in terms of when to actually kill a cursor that has been closed.Parameters: - manager_class: cursor manager to use
Changed in version 2.1+: Deprecated support for external cursor managers.
-
fsync
(**kwargs)¶ Flush all pending writes to datafiles.
Parameters: Optional parameters can be passed as keyword arguments:
- lock: If True lock the server to disallow writes.
- async: If True don’t block while synchronizing.
Warning
async and lock can not be used together.
Warning
MongoDB does not support the async option on Windows and will raise an exception on that platform.
New in version 2.0.
-
unlock
()¶ Unlock a previously locked server.
New in version 2.0.