@Html.ValidationSummary(true, “Please fix errors”) not displaying “Please fix errors” message

Question

I was following along with a tutorial on how to implement validation in my MVC web application. Below is a snippet of my View for creating a new Student:

<div class="form-horizontal">
    <h4>Student</h4>
    <hr />
    @Html.ValidationSummary(true)
    <div class="form-group">
        @Html.LabelFor(model => model.LastName, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.LastName, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.LastName)
        </div>
    </div>

Here is a snippet of my controller code:

 using System;
 using System.Collections.Generic;
 using System.Data;
 using System.Data.Entity;
 using System.Linq;
 using System.Net;
 using System.Web;
 using System.Web.Mvc;
 using ContosoUniversity.DAL;
 using ContosoUniversity.Models;

 namespace ContosoUniversity.Controllers
 {
     public class StudentController : Controller
     {
          private SchoolContext db = new SchoolContext();
          public ActionResult Create()
          {
                return View();
          }

         [HttpPost]
         [ValidateAntiForgeryToken]
         public ActionResult Create([Bind(Include = 
         "ID,LastName,FirstMidName,EnrollmentDate")] Student student)
         {

             if (ModelState.IsValid)
             {
                db.Students.Add(student);
                db.SaveChanges();
                return RedirectToAction("Index");
             }

             return View(student);

        }

My @Html.ValidationMessageFor(model => model.LastName) works without a problem. Even @Html.ValidationSummary(false) works to displays my field errors, as expected, but I don't want my field errors displayed. When I change false to true and include my custom message, the message does not show up when I run my code in the browser. I cannot figure out what is going on, and I've tried researching the answer on the web, but there is no answer that makes sense to me, even though I'm sure it has been answered somewhere. Can someone please provide me with a "layman's terms" solution to this problem?

Answer 1

To showing message change validationSummary as true and to display custom error message to non field use ModelState.AddModelError("","Error message") without key. validationSummary true case non key model error added in unordered list and field model error messages showing in ValidationMessageFor.

ModelState.AddModelError("", "Error Message");

Answer 2

像这样在第二个参数中传递所需的摘要语句。

@Html.ValidationSummary(true, "Please check form errors", new { @class = "text-danger" })