change-the-nullability-of-a-column.md

Change The Nullability Of A Column

Do you have an existing table with a column that is exactly as you want it except that it needs to be changed to either null: false or null: true?

One option is to use ActiveRecord's change_column_null method in your migration.

For example to change a nullable column to null: false, you'll want a migration like the following:

def change
  change_column_null :posts, :title, false
end

Note, if you have existing records with null values in the title column, then you'll need to deal with those before migrating.

If you want to make an existing column nullable, change that false to true:

def change
  change_column_null :posts, :title, true
end