Resolved issue with Multiple DB settings.

flask_mongoengine/connection.py

@@ -73,6 +73,11 @@ def _validate_settings(is_test, temp_db, preserved, conn_host):
                 'only when `TESTING` is set to true.'
         raise InvalidSettingsError(msg)
 
+def __get_app_config(key):
+    return (_app_instance.get(key, False)
+            if isinstance(_app_instance, dict)
+            else _app_instance.config.get(key, False))
+
 def get_connection(alias=DEFAULT_CONNECTION_NAME, reconnect=False):
     global _connections
     set_global_attributes()
@@ -98,9 +103,9 @@ def get_connection(alias=DEFAULT_CONNECTION_NAME, reconnect=False):
         conn_settings.pop('password', None)
         conn_settings.pop('authentication_source', None)
 
-        is_test = _app_instance.config.get('TESTING', False)
-        temp_db = _app_instance.config.get('TEMP_DB', False)
-        preserved = _app_instance.config.get('PRESERVE_TEMP_DB', False)
+        is_test = __get_app_config('TESTING')
+        temp_db = __get_app_config('TEMP_DB')
+        preserved = __get_app_config('PRESERVE_TEMP_DB')
 
         # Validation
         _validate_settings(is_test, temp_db, preserved, conn_host)
@@ -351,7 +356,7 @@ def create_connection(config, app):
     @param app: instance of flask.Flask
     """
     global _connection_settings, _app_instance
-    _app_instance = app
+    _app_instance = app if app else config
 
     if config is None or not isinstance(config, dict):
         raise Exception("Invalid application configuration");
@@ -363,6 +368,7 @@ def create_connection(config, app):
         connections = {}
         for conn_setting in conn_settings:
             alias = conn_setting['alias']
+            _connection_settings[alias] = conn_setting
             connections[alias] = get_connection(alias)
         return connections
     else:

tests/test_connection.py

@@ -39,6 +39,10 @@ def test_live_connection(self):
             'PASSWORD': None,
             'DB': 'test'
         }
+
+        self._do_persist(db)
+
+    def _do_persist(self, db):
         class Todo(db.Document):
             title = db.StringField(max_length=60)
             text = db.StringField()
@@ -57,6 +61,44 @@ class Todo(db.Document):
         f_to = Todo.objects().first()
         self.assertEqual(s_todo.title, f_to.title)
 
+    def test_multiple_connections(self):
+        db = MongoEngine()
+        self.app.config['TESTING'] = True
+        self.app.config['MONGODB_SETTINGS'] = [
+            {
+             "ALIAS": "default",
+             "DB":    'my_db1',
+             "HOST": 'localhost',
+             "PORT": 27017
+            },
+            {
+             "ALIAS": "my_db2",
+             "DB": 'my_db2',
+             "HOST": 'localhost',
+             "PORT": 27017
+            },
+        ]
+        class Todo(db.Document):
+            title = db.StringField(max_length=60)
+            text = db.StringField()
+            done = db.BooleanField(default=False)
+            meta = {"db_alias": "my_db2"}
+
+        db.init_app(self.app)
+        Todo.drop_collection()
+
+        # Switch DB
+        from mongoengine.context_managers import switch_db
+        with switch_db(Todo, 'default') as Todo:
+            todo = Todo()
+            todo.text = "Sample"
+            todo.title = "Testing"
+            todo.done = True
+            s_todo = todo.save()
+
+            f_to = Todo.objects().first()
+            self.assertEqual(s_todo.title, f_to.title)
+
     def test_mongodb_temp_instance(self):
         # String value used instead of boolean
         self.app.config['TESTING'] = True