javascript - How can I add, remove, or swap jQuery validation rules from a page?

Question

Note:
This question refers to a very old version of jQuery.validate() (version 1.5). This plugin now provides a built-in solution for doing this: the .rules() method that should be used instead. I'm leaving this question and answer in its original form for historical purposes for anyone who needs to maintain a legacy site that is unable to upgrade to the latest versions of jQuery and jQuery.validate().

---

I have a form that toggles what input elements are visible. I want to validate only the visible elements on the form.

I'm having a hard time getting this to function correctly. I want to disable validators for non-visible elements and I can't seem to figure out the best way to do this. Any insight to what may be wrong with my code, or my approach would be appreciated.

When visibility is toggled, I've tried a few things:

• Calling $("form").rules("remove") to clear all existing validation rules. This throws an "undefined" JavaScript exception.
• Calling $("form").validation(...options...) for the visible elements, hoping this would overwrite the rules. This only allows the first group that is validated to work. The second panel can not be validated.
• Unbinding the submit handler before calling the new validation() method. This didn't do what I would have thought. It removes all validation (seemingly) permanently and the form submits without validation.
• Clearing out the validation object with $.removeData($('form'), 'validator') before trying to call the validator again. This also doesn't work.
• This is in an ASP.NET site, so using multiple <form /> tags is out of the question since that would break the page.

I'm sort of stumped on how I can make this work. You can see a complete working demo of what I have at http://jsbin.com/ucibe3, or edit it at http://jsbin.com/ucibe3/edit. I've tried to strip it down to just the code that causes the bug.

Here are the key pieces of my code (use above links for complete working page)

HTML:

<td id="leftform">
    Left Form<br />
    Input 1: <input type="text" name="leftform_input1" /><br />
    Input 2: <input type="text" name="leftform_input2" /><br />
    <input type="submit" name="leftform_submit" value="Submit Left" />
</td>
<td id="rightform" style="visibility:hidden">
    Right Form<br />
    Input 1: <input type="text" name="rightform_input1" /><br />
    Input 2: <input type="text" name="rightform_input2" /><br />
    <input type="submit" name="rightform_submit" value="Submit Right" />
</td>

JavaScript:

$('#toggleSwitch').click(function() {
    if ($('#leftform').css("visibility") !== "hidden") {
        $('#leftform').css("visibility", "hidden");
        $('#rightform').css("visibility", "visible");
        $('form').validate({
            rules: {
                rightform_input1: { required: true },
                rightform_input2: { required: true }
            },
            messages: {
                rightform_input1: "Field is required",
                rightform_input2: "Field is required"
            }
        });
    } else {
        $('#rightform').css("visibility", "hidden");
        $('#leftform').css("visibility", "visible");
        $('form').validate({
            rules: {
                leftform_input1: { required: true },
                leftform_input2: { required: true }
            },
            messages: {
                leftform_input1: "Field is required",
                leftform_input2: "Field is required"
            }
        });
    }
});

Answer 1

Obsolete notice:
This answer refers to an extremely old version of the jQuery.validate() plugin (version 1.5) and is now obsolete as the plugin provides an official API for solving this problem. See the .rules() documentation for the current approach to solving this. I'm leaving this answer as-is to help anyone who must maintain a legacy site that is unable to upgrade to the latest versions of jQuery and jQuery.validate().

---

This uses a feature of the validator that is not well documented in the API (and by this I mean it isn't documented at all), however since it is a fundamental part of how the validator works, it is not likely to be removed even if it is undocumented.

Once you've initialized the jQuery validator, you can get access to the validator object again by calling the validate() method on the form object you applied the validator to. This validator object has a settings property, which stores the default settings, combined with the settings you applied to it in initialization.

Assuming I initialize the validator like this:

$('form').validate({
    rules: {
        leftform_input1: { required: true },
        leftform_input2: { required: true }
    },
    messages: {
        leftform_input1: "Field is required",
        leftform_input2: "Field is required"
    }
});

I can then get those exact settings out of the validator by doing the following:

var settings = $('form').validate().settings;

I can then easily work with this settings object to add or remove validators for the form.

This is how you would remove validation rules:

var settings = $('form').validate().settings;
delete settings.rules.rightform_input1;
delete settings.messages.rightform_input1;

And this is how you would add validation rules:

var settings = $('form').validate().settings;
settings.rules.leftform_input1 = {required: true};
settings.messages.leftform_input1 = "Field is required";

---

Here is a working solution for the scenario in my question. I use jQuery's extend() method to overwrite the rules and messages properties of the validate object, which is how I toggle between the two panels.

$('#toggleSwitch').click(function() {
    var settings = $('form').validate().settings;
    var leftForm = $('#leftform');
    var rightForm = $('#rightform');

    if (leftForm.css("visibility") !== "hidden") {
        leftForm.css("visibility", "hidden");
        rightForm.css("visibility", "visible");
        $.extend(settings, {
            rules: {
                rightform_input1: { required: true },
                rightform_input2: { required: true }
            },
            messages: {
                rightform_input1: "Field is required",
                rightform_input2: "Field is required"
            }
        });
    } else {
        rightForm.css("visibility", "hidden");
        leftForm.css("visibility", "visible");
        $.extend(settings, {
            rules: {
                leftform_input1: { required: true },
                leftform_input2: { required: true }
            },
            messages: {
                leftform_input1: "Field is required",
                leftform_input2: "Field is required"
            }
        });
    }
});