Case-insensitive unique index in Rails/ActiveRecord?

Question

I need to create a case-insensitive index on a column in rails. I did this via SQL:

execute(
   \"CREATE UNIQUE INDEX index_users_on_lower_email_index 
    O         


        

Answer 1

For Rails 4.2, create case-insensitive unique index in users table on name column.

Create new migration file with empty change method:

$ rails generate migration add_index_in_users_on_name

Add call of add_index method to empty change method:

add_index :users, 'lower(name)', name: 'index_users_on_lower_name', unique: true

Run Rake db:migrate task:

$ rake db:migrate

In result, index will be added correctly and file db/schema.rb contains correct add_index:

add_index "users", ["LOWER(\"NAME\")"], name: "index_users_on_lower_name", unique: true

This tested only with RDB Oracle.