public static ModelSource <TEntity> InvokeModelSource <TEntity>(this TempDataDictionary tempData)
            where TEntity : class, new()
        {
            GenericManager <BFDataContext> models = tempData.GetGenericModelSource();

            if (models == null)
            {
                models = new ModelSource <TEntity>();
                tempData.SetModelSource <TEntity>((ModelSource <TEntity>)models);
                return((ModelSource <TEntity>)models);
            }
            else if (models is ModelSource <TEntity> )
            {
                return((ModelSource <TEntity>)models);
            }
            else
            {
                return(new ModelSource <TEntity>(models));
            }
        }