Custom Validation in jQuery Unobtrusive Validation Without Field Name

Question

Is it possible, using jQuery unobtrusive validation, to specify a custom validation function that is not bound to a specific field? I mean, a validation function that is triggered when the form is validated, but not targeted at a specific form field. This is in the context of ASP.NET Core validation, and I would prefer not to add any code to the form submit handler. Essentially, I would like to keep the default behavior when I click on a submit button, but besides the usual field-oriented validation also do bespoke ("global") validation too.

Answer 1

One way to achieve this is to have an hidden field with validation attributes:

<input type="hidden" id="val" name="val" data-val="true" data-val-custom="My custom error message" />

Then hook it to unobtrusive validation:

$.validator.addMethod('custom', function (value, element, params) {
    //whatever
    return false;
});
$.validator.unobtrusive.adapters.addBool('custom');

This way it will appear as if it is general, not field-specific.