public string SaveCategory(Category category)
 {
     if (aCategoryGateway.IsCategoryExistes(category.Name))
     {
         return("Category already exists");
     }
     else
     {
         int rowAffected = aCategoryGateway.SaveCategory(category);
         if (rowAffected > 0)
         {
             return("Saved successfully");
         }
         return("Save failed");
     }
 }