How to return error from ASP.NET MVC action

ajax, asp.net, asp.net-mvc, jquery

Solution

Your ajax error handler will be called when the action doesn't return a expected status code. It will, for example, fire if the action wasn't found or if you throw a exception that you don't handle. In your case it will be called if you don't catch the error in your action (as the action will return a 500 status code).

I would, however, not do it in this way as this is probably a expected error. I would rather return json both when you succeed and when you have a error. Then you can indicate if it is a successful call or not. Something like this:

public ActionResult AddToFavourites(int entityId, string entityType)
{

    if (!Request.IsAjaxRequest())
        throw new InvalidOperationException("This action can be called only in async style.");

    try
    {
        RBParams.EntityType typeOfFavourite = (RBParams.EntityType)Enum.Parse(typeof(RBParams.EntityType), entityType);
        string status = "";

        if (typeOfFavourite == RBParams.EntityType.BusinessEntity)
        {
            status = MarkFavouriteEntity(entityId);
        }
        else if (typeOfFavourite == RBParams.EntityType.Review)
        {
            status = MarkFavouriteReview(entityId);
        }
        else
        {
            throw new InvalidOperationException("The type of the entity is not proper");
        }

        return Json(new { Success = true, Status = status });

    }
    catch (Exception ex)
    {

        return Json(new { Success = false, Message = ex.Message });
    }
}

Then you handle it in the same way as a successful call. You just check the Success property of your json response. Then you handle unexpected errors in the error callback.

Problem

Original source

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