Moved the MongoDb database connection method to the utils module

lodel/datasource/mongodb/datasource.py

 from bson.son import SON
 from collections import OrderedDict
 import pymongo
-from pymongo import MongoClient
+# from pymongo import MongoClient
 from pymongo.errors import BulkWriteError
 import urllib
 
 
 class MongoDbDataSource(GenericDataSource):
 
-    MANDATORY_CONNECTION_ARGS = ('host', 'port', 'login', 'password', 'dbname')
-
     ## @brief Instanciates a Database object given a connection name
     # @param connection_name str
     def __init__(self, connection_name='default'):
-        connection_args = self._get_connection_args(connection_name)
-        login, password, host, port, dbname = MongoDbDataSource._check_connection_args(connection_args)
-
-        # Creating of the connection
-        connection_string = 'mongodb://%s:%s@%s:%s' % (login, password, host, port)
-        self.connection = MongoClient(connection_string)
-        # Getting the database
-        self.database = self.connection[dbname]
-
-    ## @brief Gets the settings given a connection name
-    # @param connection_name str
-    # @return dict
-    # @TODO Change the return value using the Lodel 2 settings module
-    def _get_connection_args(self, connection_name):
-        return {'host': 'localhost', 'port': 28015, 'login': 'lodel_admin', 'password': 'lapwd', 'dbname': 'lodel'}
-
-    ## @brief checks if the connection args are valid and complete
-    # @param connection_args dict
-    # @return bool
-    # @todo checks on the argument types can be added here
-    @classmethod
-    def _check_connection_args(cls, connection_args):
-        errors = []
-        for connection_arg in cls.MANDATORY_CONNECTION_ARGS:
-            if connection_arg not in connection_args:
-                errors.append("Datasource connection error : %s parameter is missing." % connection_arg)
-        if len(errors) > 0 :
-            raise MongoDbDataSourceError("\r\n-".join(errors))
-
-        return (connection_args['login'], connection_args['password'], connection_args['host'],
-                connection_args['port'], connection_args['dbname'])
+        self.database = utils.mongodbconnect(connection_name)
 
     ## @brief returns a selection of documents from the datasource
     # @param target_cls Emclass

lodel/datasource/mongodb/utils.py

 # -*- coding: utf-8 -*-
 
 import pymongo
+from pymongo import MongoClient
 
 common_collections = {
     'object': 'object'
 }
 
 
+MANDATORY_CONNECTION_ARGS = ('host', 'port', 'login', 'password', 'dbname')
+
+
+class MongoDbConnectionError(Exception):
+    pass
+
+
+## @brief Creates a connection to a MongoDb database
+def mongodbconnect(connection_name):
+    connection_args = get_connection_args(connection_name)
+    checked_connection_args = check_connection_args(connection_args)
+    if len(checked_connection_args['errors']) > 0:
+        raise MongoDbConnectionError("\r\n-".join(checked_connection_args['errors']))
+
+    # connection arguments are parsed after the check
+    login, password, host, port, dbname = checked_connection_args['params']
+
+    # Connection creation
+    connection_string = 'mongodb://%s:%s@%s:%s' % (login, password, host, port)
+    connection = MongoClient(connection_string)
+
+    # Setting the database
+    database = connection[dbname]
+
+    return database
+
+
+## @brief gets the settings given a connection name
+# @param connection_name str
+# @return dict
+# @todo connect this method to the settings
+def get_connection_args(connnection_name):
+    return {'host': 'localhost', 'port': 28015, 'login': 'lodel_admin', 'password': 'lapwd', 'dbname': 'lodel'}
+
+
+## @brief Checks the settings given a connection name
+# @param connection_args dict
+# @return dict
+# @throw MongoDbDataSourceError with the list of all the found errors
+# @todo optimize the error management
+def check_connection_args(connection_args):
+    check_result = {'params': connection_args, 'errors': []}
+    for connection_arg in MANDATORY_CONNECTION_ARGS:
+        if connection_arg not in connection_args:
+            check_result['errors'].append('Datasource connection error: %s parameter is missing.' % connection_arg)
+    return check_result
+
+
 ## @brief Returns a collection name given a Emclass name
 # @param class_name str : The class name
 # @return str