How to make Html.ValidationMessage if I use ViewModel ASP.NET MVC 4

Question

I'm having trouble using Html.ValidationMessage because I use ViewModel,

this is my Controller

    public ActionResult SetDataInDataBase()
    {
        ViewData["jenisList"] = new SelectList(db.isengs, "jenis", "jenis");

        return View();
    }

    [HttpPost]
    public ActionResult SetDataInDataBase(CostVM model)
    {

        informasi item = new informasi();

        if (model.nama == null)
        {
            ModelState.AddModelError("Error", "This Field Cant Empty");
            return View(model);
        }
        else
        {
            item.nama = model.nama;
            item.alamat = model.alamat;
            item.jk = model.jk;
            item.kelas = model.kelas;
            item.jenis = model.jenis;
        }

        db.informasis.Add(item);
        db.SaveChanges();
        return RedirectToAction("Edit", "Register", new { id = item.id, id2 = item2.Id });

    }

this is my RazorView

@Html.ValidationMessage("Error")
<div class="container">
    <div class="form-group">
        <label>Nama:</label>
        @Html.TextArea("nama")
    </div>
    <div class="form-group">
        <label>Alamat:</label>
        <input class="form-control" name="alamat" placeholder="Enter Password" required/>
    </div>
    <div class="form-group">
        <label>JK:</label>
        <input class="form-control" type="radio" name="jk" value="L" required/>L<br />
        <input class="form-control" type="radio" name="jk" value="P" />P<br />
    </div>
    <div class="form-group">
        <label>Kelas:</label>
        <select name="kelas" required>
            <option value="">--Pilih Kelas--</option>
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
        </select>
    </div>
    <div class="form-group">
        <label>Jenis:</label>
        <div >
            @Html.DropDownList("jenis1", ViewBag.jenisList as SelectList, "--Jenis--", new { required = "required" })
        </div>
    </div>

    <div class="button">
        <button>Submit</button>
    </div>
</div>

I want to make if model.name is empty, show a notice or Message error "This Field Can't Empty", but I dont understand because I use ViewModel

Can someone help me show Validation Message if model.name empty?

@Html.ValidationMessageFor with @Html.TextAreaFor, @Html.TextBoxFor and @Html.DropDownListFor should be used if you're using a viewmodel class, and mark corresponding properties as [Required(ErrorMessage = "This field can't be empty")]. — Tetsuya Yamamoto
– Tetsuya Yamamoto, Commented Jan 4, 2018 at 9:13
@TetsuyaYamamoto I already sue your code, but I got error in this line @Html.DropDownList("jenis1", ViewBag.jenisList as SelectList, "--Jenis--", new { required = "required" }) if a column name is empty, maybe my return is wrong but I dont know how to fix this — Ihsan
– Ihsan, Commented Jan 5, 2018 at 1:12

M.Y.Mnu · Accepted Answer · 2018-01-05 06:23:15Z

2

You can use like below to validate error thorugh model

[Required (ErrorMessage= "jenis selection is Required")]  
public string jenisList { get; set; }

and if you want to bind drop down list using viewbag, just use Viewbag in your related action method in controller.

[HttpGet]
public ActionResult SetDataInDataBase()
{
    ViewBag.jenisList  = new SelectList(db.isengs, "jenis", "jenis");
    return View();
}

Write below code in view

@Html.DropDownList("jenis", (SelectList)ViewBag.jenisList  , "-- Choose --")
@Html.ValidationSummaryFor(model => model.jenisList, "", new { @class = "text-danger" })

edited Jan 5, 2018 at 6:23

answered Jan 4, 2018 at 9:13

M.Y.Mnu

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2 Comments

Ihsan Over a year ago

I already sue your code, but I got error in this line @Html.DropDownList("jenis1", ViewBag.jenisList as SelectList, "--Jenis--", new { required = "required" }) if a column name is empty, maybe my return is wrong but I dont know how to fix this

M.Y.Mnu Over a year ago

try now hope its help you :)

Tetsuya Yamamoto · Accepted Answer · 2018-01-04 09:25:21Z

1

This is example how you can use validation with a strongly-typed viewmodel bound to view:

Model

public class CostVM
{
   // required property attribute
   [Required(ErrorMessage = "This field can't be empty")]
   public string Name { get; set; }

   // other properties
}

View

@model CostVM

@Html.TextBoxFor(model => model.Name)
@Html.ValidationMessageFor(model => model.Name)

If you want to show all validation errors, use validation summary feature:

@Html.ValidationSummary()

Reference: Performing Simple Validation

answered Jan 4, 2018 at 9:25

Tetsuya Yamamoto

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3 Comments

Ihsan Over a year ago

I used your code, but I got error in this line @Html.DropDownList("jenis1", ViewBag.jenisList as SelectList, "--Jenis--", new { required = "required" })

Marcin Over a year ago

@Ihsan if you want to bind to model best way to do that is to use DropDownListFor(m => m.JenisList.....) But if you still want to use DropDownList("name") the 'name' should be exactly the same as property in your model.

SamuraiJack Over a year ago

wouldnt it show error when user first loads the view as model.Name will be blank the first time (get request)

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