How to make event registration fields conditionally required

[narayanis]

We've set up an event registration with a price set. Field 'Foo' is a radio with multiple price options; this field is not required so we have the -none- option at the end. Another optional price set field ('Bar') allows the user to set any registration amount. It is an integer field with the price set to $1; so if the user types 20, the registration amount is $20.

If the user selects -none- from price list 'Foo', we want to make 'Bar' required. Are there any examples that show a simple way to go about this? I thought I could use built-in jQuery validation by adding the below code to Register.extra.tpl. However, while it adds/removes the class, it doesn't seem to enforce anything.

Code: [Select]

var myAmount = $("label[for='" + $('#CIVICRM_QFID_0_14').attr('id') + "']");
$(myAmount).text("I will set my own amount");


$('input:radio').change(
    function(){

if ($('#CIVICRM_QFID_0_14').is(':checked'))
{
$('#price_44').addClass('required');
}
else
{
$('#price_44').removeClass('required');
}
    }
);

[Michael McAndrew]

Adding the classes won't do anything - since the underlying PHP does not get informed of the change.

Another approach would be to use jquery to disable / hide the submit button, and or replace it with some text which explains what the user needs to do to get it enabled again. ("Since you have selected  -none- from price list 'Foo', you need to add something to 'Bar'") or similar.

HTH

[narayanis]

Thanks Michael; I saw /templates/CRM/Form/validate.tpl, and thought perhaps its presence meant that jQuery validation was commonly available to all forms. I'll take your advice and disable the button.

[Michael McAndrew]

NP feel free to post code here once completed for other people's edification