返回modelState错误消息

Question

I have a controller action where I perform some validations. I want to use ModelState.AddModelError to summarize the errors and display all at once, but without creating a view and using return content() instead. Is this possible? Here is my code so far:

    public ActionResult Validate(string lName, string fName)

    { 
       var lName= DataContext.LName(lName);
       var fName = DataContext.FName(fName);

        if (lName == null)
        ModelState.AddModelError("lName", "Last Name " + lName + " not found);

        if (fName== null)
        ModelState.AddModelError("fName", "First Name " + fName + " not found);

        return Content("Display Error Summary");

    }

Answer 1

You are adding the errors to MdoelState but you may need to test the validity also like so:

if (!ModelState.IsValid)
    {
        return View();//Show error
    }
    else
    {
        return redirectToAction("Index")// No errors so move on
    }

And then in your Razor veiw

@Html.ValidationSummary(true)

Answer 2

You've asked this question before: returning custom error message for multiple variables

You are attempting to mix two different ideas. I would recommend following LillyPop's answer or using the answer you selected from your earlier question.