/// <summary>
 /// Initialize the command to manipulate mongo document
 /// </summary>
 public MongoDbCommand()
 {
     _context = new MongoDbDataContext();
 }
 /// <summary>
 /// Initialize the command to manipulate mongo document
 /// </summary>
 /// <param name="connectionStringSourceUrl"></param>
 /// <param name="connectionStringTargetUrl"></param>
 public MongoDbCommand(string connectionStringSourceUrl, string connectionStringTargetUrl)
 {
     _context = new MongoDbDataContext(connectionStringSourceUrl, connectionStringTargetUrl);
 }