What's the meaning of "_FORM" in ModelState?

Question

I was going through the AccountController class (the default one). I noticed that "_FORM" is used at many places with the ModelState. For, isntance:

if (String.IsNullOrEmpty(userName))
        {
            ModelState.AddModelError("username", "You must specify a username.");
        }

if (!String.Equals(password, confirmPassword, StringComparison.Ordinal))
        {
            ModelState.AddModelError("_FORM", "The new password and confirmation password do not match.");
        }

It's easy to tell the meaning for the username (as it is for for email, password, and confirmpassword). but what's "_FORM"? Has it a special meaning? I did not see where it is defined.

Thank for helping

score 3 · Accepted Answer · answered Dec 10 '09 at 16:07

3

If you don't have an input element with name="_FORM" this could be used to just add a model error which will be shown in the error summary but no inputs would appear in red.

answered Dec 10 '09 at 16:07

Darin Dimitrov

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This is exactly right. The name "_FORM" is just a dummy so that it appears in the summary, but not in any field validation message. The MVC 2 templates use the empty string ("") instead of "_FORM", but the end result is the same. – Levi Dec 10 '09 at 18:13

score 0 · Answer 2 · edited May 23 '17 at 11:43

0

It has meaning in MVC 2 as a way to specify a validation summary error, as described above.

But in MVC 3 and later, you need to pass an empty string as the key parameter to ModelState.AddModelError(). Passing "_FORM" to denote a validation summary error doesn't seem to work any longer.See this question for more details.

edited May 23 '17 at 11:43

Community

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answered Sep 20 '12 at 01:20

Ivan Karajas

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What's the meaning of "_FORM" in ModelState?

2 Answers2