Change column in Rails to be unique

Question

I know many similar questions have been asked before but I haven't found this question exactly (maybe it's just not possible).

So I have a Column_A in my Rails table (using MySQL). Recently we've had the need to enforce uniqueness on this column.

Is it possible to do a change on this column to make it unique?

The only other solution I came up with is to create a temporary unique column and shuffle everything around. Which would be a pain.

Thanks!

Answer 1

Simple two step process:

1: Create a migration

change_column :table_name, :column_name, :string, unique: true

2: Add validation in your model

validates_uniqueness_of :column_name