Rails & Postgresql create a field that auto increments from 1

Question

I'm looking to create a field called id_visual in my table orders which starts at 1 and auto increments from there. I could create a method in my model to do it but I thought there must be a better more foolproof way. Any ideas?

Answer 1

From what I can tell, you want a secondary id based on the primary id? The identity key can only be table based and can not be dependent on another key. You will have to do this in code and then save it to a new field on before_create. The easiest way to do this is for each order that you want to id, get the count of all orders less than or equal to the one you are working with based on whatever the primary key is. Its a simple one query calculation.