Question

I’ve got an editor template which renders out a checkbox:

@Html.CheckBoxFor(model => model.Follow)

Which renders something like this:

<input checked="checked" data-val="true" data-val-required="The Follow field is required." id="Follow" name="Follow" type="checkbox" value="true" />
<input name="Follow" type="hidden" value="false" />

AFAIK the hidden field is something to do with catering when an unchecked box isn’t sent to the server or something.

Anyway, if i take a look at the Request.Form["Follow"] when the checkbox is checked, i see a value of “true,false”.

How do i coerce a bool from this value? Do i simply ignore the second field? (e.g the hidden field).

I’m doing this is a base controller (protected method, invoked from child controller), so i don’t have a strongly-typed view model, only the raw Request object.

Can anyone help? Or alternatively, if someone could point me to where in the MVC source code this happens, i could take a look myself, but not sure where to start looking.

Answer 1

As far as i know, the extra hidden field is because if the checkbox is NOT checked, that input will not be submitted with the form and therefore we need the hidden field with the value of false.

So the only solution is can think of is this:

var rawFollow = Request.Form["Follow"];
var rawFollows = rawFollow.Split(',');
if (rawFollows.Count() > 1)
{
   rawFollow = rawFollows[0];
}

But this seems hacky (and what about the order of the elements on the page, what if for some reason the hidden field was FIRST, then it would always evaluate to false), which is why i’m wondering how the MVC source does this.