CODEWITHSUNDEEP
c#asp.netasp.net-mvcasp.net-mvc-4
mbrc
mbrc

Reputation: 3973

CheckBox lists in ASP.NET MVC and bind it back to controller

 Html.CheckBox("SelectedStudents", false, new { @class = "check-item", id = x.Id, value = x.Id })

which produce

<input checked="checked" class="check-item" id="4507" name="SelectedStudents" value="4507" type="checkbox">

<input checked="checked" class="check-item" id="4507" name="SelectedStudents" value="4508" type="checkbox">

<input checked="checked" class="check-item" id="4507" name="SelectedStudents" value="4509" type="checkbox">

In mvc model I have

public IEnumerable<string> SelectedStudents { get; set; }

but when I post back, SelectedStudents are always null. Why? In this howto http://benfoster.io/blog/checkbox-lists-in-aspnet-mvc is written:

The ASP.NET MVC modelbinder is smart enough to map the selected items to this property.

but in my example is always null. Why? How to write more checkboxes and bind it back

Upvotes: 4

Views: 11879

Answers (4)

Moe
Moe

Reputation: 1599

You should be using a strongly typed editor to be able to pass the result to the controller (Model binder).

I prefer to do it this way.

Model

public class YourViewModel
{
     public List<SelectListItem> Students
        {
            get;
            set;
        }
}

Controller Get

Students= service.GetStudents(); //Fill the list

View

  @for (var i = 0; i < Model.Students.Count; i++)
                {

                    @Html.CheckBoxFor(m => m.Students[i].Selected)
                    @Html.HiddenFor(m => m.Students[i].Text)
                    @Html.HiddenFor(m => m.Students[i].Value)
                    <span>@Model.Students[i].Text</span>
                }

Controller Post

[HttpPost]
        public ActionResult Create(YourViewModel model)
        {
          foreach(var student in model.Students)
          {
            if(student.Selected) { // Do your logic}
          }
        }

Alternatively You could use an array or List of string. A ListBox is used in this example.

public string[] SelectedStudents{ get; set; }

@Html.ListBoxFor(s => s.SelectedStudents, new MultiSelectList(Model.Students, "Value", "Text", Model.SelectedStudents), new { @class = "form-control", style = "height:250px; width:100%" })

Upvotes: 12

Fran
Fran

Reputation: 6530

See my answer here How to bind checkbox values to a list of ints?.

The nice thing about this is that it separates concerns between your controller and ui nicely. The html extension methods also create correct html using label and input for the checkbox. and there is no need for hidden fields.

Upvotes: 1

Chris Pratt
Chris Pratt

Reputation: 239430

You need to use a mutable type, like List<string>.

public List<string> SelectedStudents { get; set; }

Upvotes: 0

J4ime
J4ime

Reputation: 155

Do you try it with CheckBoxListFor?? You need to associate the checkbox with model and should not have the same ID and name

@Html.CheckBoxListFor(model => model.SelectedSources, Model.SubscriptionSources)

Upvotes: 0

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