Add and validate mandatory field in order-address payment step

[jacobohidalgo]

Hi everybody. I'm trying to add a new mandatory field in order-address payment step. I have modified the order-address.tpl to show the new required field. I also save the value of this new field in the database and relate it with the order if the user completes its order.

 

The problem is that I want to validate that step so that when the user clicks on the "Continue" button to go to the next step and that field is empty or if it has an incorrect value my website should show a message telling the user that that field can not be empty.

 

Please help.