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Author SHA1 Message Date
Stefan Wojcik
2c247869f0 revamp the "connecting" user guide and test more ways of connecting to a replica set 2017-02-26 20:54:39 -05:00
3 changed files with 62 additions and 40 deletions

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@ -42,13 +42,18 @@ the :attr:`host` to
will establish connection to ``production`` database using
``admin`` username and ``qwerty`` password.
ReplicaSets
===========
Replica Sets
============
MongoEngine supports
:class:`~pymongo.mongo_replica_set_client.MongoReplicaSetClient`. To use them,
please use an URI style connection and provide the ``replicaSet`` name
in the connection kwargs.
MongoEngine supports connecting to replica sets::
from mongoengine import connect
# Regular connect
connect('dbname', replicaset='rs-name')
# MongoDB URI-style connect
connect(host='mongodb://localhost/dbname?replicaSet=rs-name')
Read preferences are supported through the connection or via individual
queries by passing the read_preference ::
@ -59,76 +64,74 @@ queries by passing the read_preference ::
Multiple Databases
==================
Multiple database support was added in MongoEngine 0.6. To use multiple
databases you can use :func:`~mongoengine.connect` and provide an `alias` name
for the connection - if no `alias` is provided then "default" is used.
To use multiple databases you can use :func:`~mongoengine.connect` and provide
an `alias` name for the connection - if no `alias` is provided then "default"
is used.
In the background this uses :func:`~mongoengine.register_connection` to
store the data and you can register all aliases up front if required.
Individual documents can also support multiple databases by providing a
`db_alias` in their meta data. This allows :class:`~pymongo.dbref.DBRef` objects
to point across databases and collections. Below is an example schema, using
3 different databases to store data::
`db_alias` in their meta data. This allows :class:`~pymongo.dbref.DBRef`
objects to point across databases and collections. Below is an example schema,
using 3 different databases to store data::
class User(Document):
name = StringField()
meta = {"db_alias": "user-db"}
meta = {'db_alias': 'user-db'}
class Book(Document):
name = StringField()
meta = {"db_alias": "book-db"}
meta = {'db_alias': 'book-db'}
class AuthorBooks(Document):
author = ReferenceField(User)
book = ReferenceField(Book)
meta = {"db_alias": "users-books-db"}
meta = {'db_alias': 'users-books-db'}
Context Managers
================
Sometimes you may want to switch the database or collection to query against
for a class.
Sometimes you may want to switch the database or collection to query against.
For example, archiving older data into a separate database for performance
reasons or writing functions that dynamically choose collections to write
document to.
a document to.
Switch Database
---------------
The :class:`~mongoengine.context_managers.switch_db` context manager allows
you to change the database alias for a given class allowing quick and easy
access the same User document across databases::
access to the same User document across databases::
from mongoengine.context_managers import switch_db
class User(Document):
name = StringField()
meta = {"db_alias": "user-db"}
meta = {'db_alias': 'user-db'}
with switch_db(User, 'archive-user-db') as User:
User(name="Ross").save() # Saves the 'archive-user-db'
User(name='Ross').save() # Saves the 'archive-user-db'
Switch Collection
-----------------
The :class:`~mongoengine.context_managers.switch_collection` context manager
allows you to change the collection for a given class allowing quick and easy
access the same Group document across collection::
access to the same Group document across collection::
from mongoengine.context_managers import switch_collection
class Group(Document):
name = StringField()
Group(name="test").save() # Saves in the default db
Group(name='test').save() # Saves in the default db
with switch_collection(Group, 'group2000') as Group:
Group(name="hello Group 2000 collection!").save() # Saves in group2000 collection
Group(name='hello Group 2000 collection!').save() # Saves in group2000 collection
.. note:: Make sure any aliases have been registered with

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@ -2,13 +2,13 @@
Installing MongoEngine
======================
To use MongoEngine, you will need to download `MongoDB <http://mongodb.org/>`_
To use MongoEngine, you will need to download `MongoDB <http://mongodb.com/>`_
and ensure it is running in an accessible location. You will also need
`PyMongo <http://api.mongodb.org/python>`_ to use MongoEngine, but if you
install MongoEngine using setuptools, then the dependencies will be handled for
you.
MongoEngine is available on PyPI, so to use it you can use :program:`pip`:
MongoEngine is available on PyPI, so you can use :program:`pip`:
.. code-block:: console

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@ -198,19 +198,6 @@ class ConnectionTest(unittest.TestCase):
self.assertTrue(isinstance(db, pymongo.database.Database))
self.assertEqual(db.name, 'test')
def test_connect_uri_with_replicaset(self):
"""Ensure connect() works when specifying a replicaSet."""
if IS_PYMONGO_3:
c = connect(host='mongodb://localhost/test?replicaSet=local-rs')
db = get_db()
self.assertTrue(isinstance(db, pymongo.database.Database))
self.assertEqual(db.name, 'test')
else:
# PyMongo < v3.x raises an exception:
# "localhost:27017 is not a member of replica set local-rs"
with self.assertRaises(MongoEngineConnectionError):
c = connect(host='mongodb://localhost/test?replicaSet=local-rs')
def test_uri_without_credentials_doesnt_override_conn_settings(self):
"""Ensure connect() uses the username & password params if the URI
doesn't explicitly specify them.
@ -332,6 +319,38 @@ class ConnectionTest(unittest.TestCase):
self.assertEqual(dict(conn1.write_concern), {'w': 1, 'j': True})
self.assertEqual(dict(conn2.write_concern), {'w': 1, 'j': True})
def test_connect_with_replicaset_via_uri(self):
"""Ensure connect() works when specifying a replicaSet via the
MongoDB URI.
"""
if IS_PYMONGO_3:
c = connect(host='mongodb://localhost/test?replicaSet=local-rs')
db = get_db()
self.assertTrue(isinstance(db, pymongo.database.Database))
self.assertEqual(db.name, 'test')
else:
# PyMongo < v3.x raises an exception:
# "localhost:27017 is not a member of replica set local-rs"
with self.assertRaises(MongoEngineConnectionError):
c = connect(host='mongodb://localhost/test?replicaSet=local-rs')
def test_connect_with_replicaset_via_kwargs(self):
"""Ensure connect() works when specifying a replicaSet via the
connection kwargs
"""
if IS_PYMONGO_3:
c = connect(replicaset='local-rs')
self.assertEqual(c._MongoClient__options.replica_set_name,
'local-rs')
db = get_db()
self.assertTrue(isinstance(db, pymongo.database.Database))
self.assertEqual(db.name, 'test')
else:
# PyMongo < v3.x raises an exception:
# "localhost:27017 is not a member of replica set local-rs"
with self.assertRaises(MongoEngineConnectionError):
c = connect(replicaset='local-rs')
def test_datetime(self):
connect('mongoenginetest', tz_aware=True)
d = datetime.datetime(2010, 5, 5, tzinfo=utc)