2/21/2012 ASP.Net MVC Unobtrusive Validation Bug

If you use the ASP.Net MVC 3 [Compare] validation attribute on a model property, then include that model as a property in a parent model (so that the field name becomes Parent.ChildProperty), the built-in unobtrusive client validation will choke, and will always report the field as having an error.

This is due to a bug on line 288 of jquery.validate.unobtrusive.js:

adapters.add("equalto", ["other"], function (options) {
    var prefix = getModelPrefix(options.element.name),
        other = options.params.other,
        fullOtherName = appendModelPrefix(other, prefix),
        element = $(options.form).find(":input[name=" + fullOtherName + "]")[0];

    setValidationValues(options, "equalTo", element);
});

Because the value of the name attribute selector is not quoted, this fails if the name contains a ..

The simplest fix is to add quotes around the concatenated value.  However, the jQuery selector there is overkill.  HTML form elements have properties for each named input, so you can do this instead:

adapters.add("equalto", ["other"], function (options) {
    var prefix = getModelPrefix(options.element.name),
        other = options.params.other,
        fullOtherName = appendModelPrefix(other, prefix),
        element = options.form[fullOtherName];
    if (!element)
        throw new Error(fullOtherName + " not found");
    //If there are multiple inputs with that name, get the first one
    if (element.length && element[0])        
        element = element[0];
    setValidationValues(options, "equalTo", element);
});