Made connection lazy

docs/apireference.rst

@@ -38,6 +38,8 @@ Fields
 
 .. autoclass:: mongoengine.FloatField
 
+.. autoclass:: mongoengine.BooleanField
+
 .. autoclass:: mongoengine.DateTimeField
 
 .. autoclass:: mongoengine.EmbeddedDocumentField

mongoengine/connection.py

@@ -10,6 +10,10 @@ _connection_settings = {
     'pool_size': 1,
 }
 _connection = None
+
+_db_name = None
+_db_username = None
+_db_password = None
 _db = None
 
 
@@ -19,14 +23,30 @@ class ConnectionError(Exception):
 
 def _get_connection():
     global _connection
+    # Connect to the database if not already connected
     if _connection is None:
+        try:
             _connection = Connection(**_connection_settings)
+        except:
+            raise ConnectionError('Cannot connect to the database')
     return _connection
 
 def _get_db():
-    global _db
+    global _db, _connection
+    # Connect if not already connected
+    if _connection is None:
+        _connection = _get_connection()
+
     if _db is None:
-        raise ConnectionError('Not connected to database')
+        # _db_name will be None if the user hasn't called connect()
+        if _db_name is None:
+            raise ConnectionError('Not connected to the database')
+
+        # Get DB from current connection and authenticate if necessary
+        _db = _connection[_db_name]
+        if _db_username and _db_password:
+            _db.authenticate(_db_username, _db_password)
+
     return _db
 
 def connect(db, username=None, password=None, **kwargs):
@@ -35,12 +55,8 @@ 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 _db
+    global _connection_settings, _db_name, _db_username, _db_password
-
     _connection_settings.update(kwargs)
-    connection = _get_connection()
+    _db_name = db
-    # Get DB from connection and auth if necessary
+    _db_username = username
-    _db = connection[db]
+    _db_password = password
-    if username is not None and password is not None:
-        _db.authenticate(username, password)
-