Fix connect/disconnect functions

- expose disconnect
- disconnect cleans _connection_settings
- disconnect cleans cached collection in Document._collection
- re-connecting with the same alias raise an error (must call disconnect in between)

mongoengine/base/common.py

@@ -13,7 +13,7 @@ _document_registry = {}
 
 
 def get_document(name):
-    """Get a document class by name."""
+    """Get a registered Document class by name."""
     doc = _document_registry.get(name, None)
     if not doc:
         # Possible old style name
@@ -30,3 +30,12 @@ def get_document(name):
             been imported?
         """.strip() % name)
     return doc
+
+
+def _get_documents_by_db(connection_alias, default_connection_alias):
+    """Get all registered Documents class attached to a given database"""
+    def get_doc_alias(doc_cls):
+        return doc_cls._meta.get('db_alias', default_connection_alias)
+
+    return [doc_cls for doc_cls in _document_registry.values()
+            if get_doc_alias(doc_cls) == connection_alias]

mongoengine/connection.py

@@ -3,11 +3,13 @@ import six
 
 from mongoengine.pymongo_support import IS_PYMONGO_3
 
-__all__ = ['MongoEngineConnectionError', 'connect', 'register_connection',
-           'DEFAULT_CONNECTION_NAME', 'get_db']
+__all__ = ['MongoEngineConnectionError', 'connect', 'disconnect', 'disconnect_all',
+           'register_connection', 'DEFAULT_CONNECTION_NAME', 'DEFAULT_DATABASE_NAME',
+           'get_db', 'get_connection']
 
 
 DEFAULT_CONNECTION_NAME = 'default'
+DEFAULT_DATABASE_NAME = 'test'
 
 if IS_PYMONGO_3:
     READ_PREFERENCE = ReadPreference.PRIMARY
@@ -28,18 +30,17 @@ _connections = {}
 _dbs = {}
 
 
-def register_connection(alias, db=None, name=None, host=None, port=None,
-                        read_preference=READ_PREFERENCE,
-                        username=None, password=None,
-                        authentication_source=None,
-                        authentication_mechanism=None,
-                        **kwargs):
-    """Add a connection.
+def _get_connection_settings(
+        db=None, name=None, host=None, port=None,
+        read_preference=READ_PREFERENCE,
+        username=None, password=None,
+        authentication_source=None,
+        authentication_mechanism=None,
+        **kwargs):
+    """Get the connection settings as a dict
 
-    :param alias: the name that will be used to refer to this connection
-        throughout MongoEngine
-    :param name: the name of the specific database to use
     :param db: the name of the database to use, for compatibility with connect
+    :param name: the name of the specific database to use
     :param host: the host name of the :program:`mongod` instance to connect to
     :param port: the port that the :program:`mongod` instance is running on
     :param read_preference: The read preference for the collection
@@ -59,7 +60,7 @@ def register_connection(alias, db=None, name=None, host=None, port=None,
     .. versionchanged:: 0.10.6 - added mongomock support
     """
     conn_settings = {
-        'name': name or db or 'test',
+        'name': name or db or DEFAULT_DATABASE_NAME,
         'host': host or 'localhost',
         'port': port or 27017,
         'read_preference': read_preference,
@@ -125,17 +126,74 @@ def register_connection(alias, db=None, name=None, host=None, port=None,
     kwargs.pop('is_slave', None)
 
     conn_settings.update(kwargs)
+    return conn_settings
+
+
+def register_connection(alias, db=None, name=None, host=None, port=None,
+                        read_preference=READ_PREFERENCE,
+                        username=None, password=None,
+                        authentication_source=None,
+                        authentication_mechanism=None,
+                        **kwargs):
+    """Register the connection settings.
+
+    :param alias: the name that will be used to refer to this connection
+        throughout MongoEngine
+    :param name: the name of the specific database to use
+    :param db: the name of the database to use, for compatibility with connect
+    :param host: the host name of the :program:`mongod` instance to connect to
+    :param port: the port that the :program:`mongod` instance is running on
+    :param read_preference: The read preference for the collection
+       ** Added pymongo 2.1
+    :param username: username to authenticate with
+    :param password: password to authenticate with
+    :param authentication_source: database to authenticate against
+    :param authentication_mechanism: database authentication mechanisms.
+        By default, use SCRAM-SHA-1 with MongoDB 3.0 and later,
+        MONGODB-CR (MongoDB Challenge Response protocol) for older servers.
+    :param is_mock: explicitly use mongomock for this connection
+        (can also be done by using `mongomock://` as db host prefix)
+    :param kwargs: ad-hoc parameters to be passed into the pymongo driver,
+        for example maxpoolsize, tz_aware, etc. See the documentation
+        for pymongo's `MongoClient` for a full list.
+
+    .. versionchanged:: 0.10.6 - added mongomock support
+    """
+    conn_settings = _get_connection_settings(
+        db=db, name=name, host=host, port=port,
+        read_preference=read_preference,
+        username=username, password=password,
+        authentication_source=authentication_source,
+        authentication_mechanism=authentication_mechanism,
+        **kwargs)
     _connection_settings[alias] = conn_settings
 
 
 def disconnect(alias=DEFAULT_CONNECTION_NAME):
     """Close the connection with a given alias."""
+    from mongoengine.base.common import _get_documents_by_db
+
     if alias in _connections:
         get_connection(alias=alias).close()
         del _connections[alias]
+
     if alias in _dbs:
+        # Detach all cached collections in Documents
+        for doc_cls in _get_documents_by_db(alias, DEFAULT_CONNECTION_NAME):
+            if hasattr(doc_cls, '_disconnect'):
+                doc_cls._disconnect()
+
         del _dbs[alias]
 
+    if alias in _connection_settings:
+        del _connection_settings[alias]
+
+
+def disconnect_all():
+    """Close all registered database."""
+    for alias in list(_connections.keys()):
+        disconnect(alias)
+
 
 def get_connection(alias=DEFAULT_CONNECTION_NAME, reconnect=False):
     """Return a connection with a given alias."""
@@ -265,7 +323,14 @@ def connect(db=None, alias=DEFAULT_CONNECTION_NAME, **kwargs):
 
     .. versionchanged:: 0.6 - added multiple database support.
     """
-    if alias not in _connections:
+    if alias in _connections:
+        prev_conn_setting = _connection_settings[alias]
+        new_conn_settings = _get_connection_settings(db, **kwargs)
+
+        if new_conn_settings != prev_conn_setting:
+            raise MongoEngineConnectionError(
+                'A different connection with alias `%s` was already registered. Use disconnect() first' % alias)
+    else:
         register_connection(alias, db, **kwargs)
 
     return get_connection(alias)

mongoengine/document.py

@@ -188,10 +188,16 @@ class Document(six.with_metaclass(TopLevelDocumentMetaclass, BaseDocument)):
         return get_db(cls._meta.get('db_alias', DEFAULT_CONNECTION_NAME))
 
     @classmethod
-    def _get_collection(cls):
-        """Return a PyMongo collection for the document."""
-        if not hasattr(cls, '_collection') or cls._collection is None:
+    def _disconnect(cls):
+        """Detach the Document class from the (cached) database collection"""
+        cls._collection = None
 
+    @classmethod
+    def _get_collection(cls):
+        """Return the corresponding PyMongo collection of this document.
+        Upon the first call, it will ensure that indexes gets created. The returned collection then gets cached
+        """
+        if not hasattr(cls, '_collection') or cls._collection is None:
             # Get the collection, either capped or regular.
             if cls._meta.get('max_size') or cls._meta.get('max_documents'):
                 cls._collection = cls._get_capped_collection()