Why I can't set a value on a asp:CheckBox?

Question

There isn't the attribute Value :

<asp:CheckBox ID="CheckBox1" runat="server" />

while on standard HTML this is allowed :

<input type="checkbox" ID="CheckBox1" value="My Valyue" />

why?

Answer 1

The Text property is used to render a label for the checkbox.

The control has an InputAttributes property that you can add to:

myChk.InputAttributes.Add("value", "My Value");

I believe that if you simply add the value attribute to the markup, this will also get populated.

You can access the value like so:

myChk.InputAttributes["value"];

---

To answer the question of why Value is not a build in attribute to the CheckBox control:

A CheckBox in isolation (just by itself) needs no value. By definition it is a boolean and is identified by its ID. All you need to do is check whether it was checked or not.

The value comes into play when you group checkboxes and there is a control for that - the CheckBoxList that uses ListItem - each ListItem does have a Value property.

Answer 2

Instead of using the asp:CheckBox control, use the html input checkbox, and run it at the server.

<input type="checkbox" id="ck" runat="server" value='<%# Eval("Value") %>' />
<asp:Label ID="lbl" runat="server" AssociatedControlID="ck" Text='<%# Eval("Name") %>'></asp:Label>

Now you can reference it from codebehind as an HtmlInputCheckBox (my latest example is inside a repeater, so I can decorate this substitute for a checkbox list with other elements, like a tool tip image).

foreach (RepeaterItem repeaterItem in repCheckboxes.Items)
{
    HtmlInputCheckBox listItem = (HtmlInputCheckBox)repeaterItem.FindControl("ck");
    if (listItem.Checked)
    {
         string val = listItem.Value;
         ...

I know this does not answer the "why" of the OP, but this comes up high in searches for this exact problem, and this is a good solution. As for why, I think MS goofed by leaving it out, since you don't have control over the html in a CheckBoxList