CB Code Field Validation

I have two dropdown input fields, Make and Model, which form a Field Group. I am trying to use CB Code Field Validation on these two fields and have run into a problem.

I can force a selection for 'Make' by specifying that it is a Required field.

I cannot specify that 'Model' is a Required field as this is dependent on the value selected for 'Make'.

How do I test to see whether a value has been selected for 'Model'?

These lines of code work as expected:
if ('[cb_make]' != "None" && '[value]' == "None") {return false;}
AND
if ('[value]' != "xxxx") {return false;}

To test whether any value at all has been entered I have tried:

if (!isset('[value]')) {return false;}
if (empty('[value]')) {return false;}
if (is_null('[value]')) {return false;}
if ('[value]' == "") {return false;}

none of which cause a validation failure and an error message. Instead the database is updated and I get a message confirming that.

Am I using the wrong command? wrong syntax?

I am running PHP 7.3.3 under XAMPP on a Win 10 PC, Joomla 3.9.24, CB 2.5.0

If nothing is selected it should just be an empty string. So for the example the below should be fine for excluding empty.


You need to return true as we want it to pass and skip the validation. If you return false it fails the validation. Be sure you also have additional fields configured like the following example if using the ajax validation feature.

Ajax Validation: Enabled
Additional Fields: cb_make

Thank you for your quick reply.

I had already checked that:

Ajax Validation: Enabled
Additional Fields: cb_make

Returning false for an empty string is what I want to do in this instance, since if Make is not "None" then Model must not be empty (i.e. it's value must be selected from the dropdown list). I have tried again, replacing my double quotes with single quotes

if ('[value]' == '') {return false};

but with the same result.

Is it possible that I have misunderstood the point at which the validation code runs? If I select a value from the Model dropdown it is evident that something is triggered as the little rotating symbol appears briefly. If I don't select any Model, or if I select the empty option, then the little rotating symbol does not appear; clicking on the Update button doesn't appear to trigger the validation code.

If the field isn't marked required then you hit a special case in the validation that's applied to all validation. A not required field is always allowed to be empty as it's an optional field. I don't think you'll be able to have what you're wanting without the field being marked required.

I wondered if that was the case and it is good to have it confirmed:)

I've since been trying all sorts of different approaches to solving the overarching problem. Basically, for any given member the set of fields that make up the Field Group can occur 0-n times; in the majority of cases it occurs only once but our system allocates space for three sets per member and we are wasting a lot of disk space. However no occurrences is common and several members require space for up to 9 sets. The multi-field validation was the most obvious route for what I am trying to achieve and I will try other ways.

If it's of any help to someone who runs into a similar requirement, I'd just like to mention that a) you guys have already posted (some time ago and on a different thread) that CB Conditional is not valid for fields within Field Groups and b) a Field Group can be optional, even if fields within it are required. This information has pointed me to a possible solution and may be of help to someone else.

Thank you for your time and patience, and while it's not possible to achieve the validation I was attempting the information you provided in response is invaluable.