Fix changing databases

Conflicts:

	mongoengine/connection.py
	mongoengine/queryset.py

mongoengine/connection.py

@@ -4,11 +4,12 @@ import multiprocessing
 __all__ = ['ConnectionError', 'connect']
 
 
-_connection_settings = {
+_connection_defaults = {
     'host': 'localhost',
     'port': 27017,
 }
 _connection = {}
+_connection_settings = _connection_defaults.copy()
 
 _db_name = None
 _db_username = None
@@ -20,25 +21,25 @@ class ConnectionError(Exception):
     pass
 
 
-def _get_connection():
+def _get_connection(reconnect=False):
     global _connection
     identity = get_identity()
     # Connect to the database if not already connected
-    if _connection.get(identity) is None:
+    if _connection.get(identity) is None or reconnect:
         try:
             _connection[identity] = Connection(**_connection_settings)
         except:
             raise ConnectionError('Cannot connect to the database')
     return _connection[identity]
 
-def _get_db():
+def _get_db(reconnect=False):
     global _db, _connection
     identity = get_identity()
     # Connect if not already connected
-    if _connection.get(identity) is None:
-        _connection[identity] = _get_connection()
+    if _connection.get(identity) is None or reconnect:
+        _connection[identity] = _get_connection(reconnect=reconnect)
 
-    if _db.get(identity) is None:
+    if _db.get(identity) is None or reconnect:
         # _db_name will be None if the user hasn't called connect()
         if _db_name is None:
             raise ConnectionError('Not connected to the database')
@@ -61,9 +62,10 @@ def connect(db, username=None, password=None, **kwargs):
     the default port on localhost. If authentication is needed, provide
     username and password arguments as well.
     """
-    global _connection_settings, _db_name, _db_username, _db_password
-    _connection_settings.update(kwargs)
+    global _connection_settings, _db_name, _db_username, _db_password, _db
+    _connection_settings = dict(_connection_defaults, **kwargs)
     _db_name = db
     _db_username = username
     _db_password = password
-    return _get_db()
+    return _get_db(reconnect=True)
+