How to handle checkboxes in ASP.NET MVC forms?

I'm surprised none of these answers used the built in MVC features for this.

I wrote a blog post about this here, which even actually links the labels to the checkbox. I used the EditorTemplate folder to accomplish this in a clean and modular way.

You will simply end up with a new file in the EditorTemplate folder that looks like this:

@model SampleObject

@Html.CheckBoxFor(m => m.IsChecked)
@Html.HiddenFor(m => m.Id)
@Html.LabelFor(m => m.IsChecked, Model.Id)

in your actual view, there will be no need to loop this, simply 1 line of code:

@Html.EditorFor(x => ViewData.Model)

Visit my blog post for more details.

Here's what I've been doing.

View:

<input type="checkbox" name="applyChanges" />

Controller:

var checkBox = Request.Form["applyChanges"];

if (checkBox == "on")
{
...
}

I found the Html.* helper methods not so useful in some cases, and that I was better off doing it in plain old HTML. This being one of them, the other one that comes to mind is radio buttons.

Edit: this is on Preview 5, obviously YMMV between versions.

I'd also like to point out that you can name each checkbox a different name, and have that name part of the actionresults parameters.

Example,

View:

 <%= Html.CheckBox("Rs232CheckBox", false, new { @id = "rs232" })%>RS-232

 <%= Html.CheckBox("Rs422CheckBox", false, new { @id = "rs422" })%>RS-422

Controller:

public ActionResults MyAction(bool Rs232CheckBox, bool Rs422CheckBox) {
    ...
}

The values from the view are passed to the action since the names are the same.

I know this solution isn't ideal for your project, but I thought I'd throw the idea out there.

I know that this question was written when MVC3 wasn't out, but for anyone who comes to this question and are using MVC3, you may want the "correct" way to do this.

While I think that doing the whole

Contains("true");

thing is great and clean, and works on all MVC versions, the problem is that it doesn't take culture into account (as if it really matters in the case of a bool).

The "correct" way to figure out the value of a bool, at least in MVC3, is to use the ValueProvider.

var value = (bool)ValueProvider.GetValue("key").ConvertTo(typeof(bool));

I do this in one of my client's sites when I edit permissions:

var allPermissionsBase = Request.Params.AllKeys.Where(x => x.Contains("permission_")).ToList();
var allPermissions = new List<KeyValuePair<int, bool>>();

foreach (var key in allPermissionsBase)
{
     // Try to parse the key as int
     int keyAsInt;
     int.TryParse(key.Replace("permission_", ""), out keyAsInt);

     // Try to get the value as bool
     var value = (bool)ValueProvider.GetValue(key).ConvertTo(typeof(bool));
}

Now, the beauty of this is you can use this with just about any simple type, and it will even be correct based on the Culture (think money, decimals, etc).

The ValueProvider is what is used when you form your Actions like this:

public ActionResult UpdatePermissions(bool permission_1, bool permission_2)

but when you are trying to dynamically build these lists and check the values, you will never know the Id at compile time, so you have to process them on the fly.

The easiest way to do is so...

You set the name and value.

<input type="checkbox" name="selectedProducts" value="@item.ProductId" />@item.Name

Then on submitting grab the values of checkboxes and save in an int array. then the appropriate LinQ Function. That's it..

[HttpPost]
        public ActionResult Checkbox(int[] selectedObjects)
        {
            var selected = from x in selectedObjects
                           from y in db
                           where y.ObjectId == x
                           select y;                   

            return View(selected);
        }