# Cartthrob 3 : how to make a custom_data field required in checkout form?

I created a custom field in Order channel and created an imput named custom_data[nameofmycustomfield] in my checkout form as explained in the docs here.

But I can't make it required (validation sensitive). When I put his name as parameter 'required' 's value it doesn't work.

How can I do?

custom_data[nameofmycustomfield]
as the field name in the required parameter, not just nameofmycustomfield.