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up vote 47 down vote favorite
8

I just noticed that Html.CheckBox("foo") generates 2 inputs instead of one, anybody knows why is this so ?

<input id="foo" name="foo" type="checkbox" value="true" />
<input name="foo" type="hidden" value="false" />
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Really crazy))) –  Andrei Mikhalevich Jun 24 at 10:52
 
stackoverflow.com/questions/2697299/… –  Nikhil waghmare Aug 27 at 8:44

3 Answers

up vote 53 down vote accepted

If checkbox is not selected, form field is not submitted. That is why there is always false value in hidden field. If you leave checkbox unchecked, form will still have value from hidden field. That is how ASP.NET MVC handles checkbox values.

If you want to confirm that, place a checkbox on form not with Html.Hidden, but with <input type="checkbox" name="MyTestCheckboxValue"></input>. Leave checkbox unchecked, submit form and look at posted request values on server side. You'll see that there is no checkbox value. If you had hidden field, it would contain MyTestCheckboxValue entry with false value.

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If you didn't check the box then obviously the answer is false, no need for it to send back the item. Silly design in my opinion. –  Lé Muffin Man Sep 18 at 23:24
up vote 4 down vote

when the check box is checked and submitted perform this 

if ($('[name="foo"]:checked').length > 0)
    $('[name="foo"]:hidden').val(true);

Refer

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up vote 3 down vote

The manual approach is this:

bool IsDefault = (Request.Form["IsDefault"] != "false");
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And is this guaranteed to get you the checkbox type value and not the hidden type value? –  Brian Sweeney Mar 13 '12 at 19:21
 
that is irrelevant. When the checkbox is not checked, it does not post. So the hiddenbox will have 'false'. If the checkbox is checked the value of 'true, true' is returned (i think), and this does not equal 'false'. –  Valamas - AUS Jun 12 '12 at 21:33
2  
No, when checkbox is checked, both true and false are posted because both checkbox and hidden fields are valid controls to be sent back. Mvc binder then checks if true value exists for a given namve and if so it prefers true value. You can check this by viewing the posted data. It will have both true and false values against single name. –  ZafarYousafi Mar 23 at 14:47

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