How to change column null in rails?

less than 1 minute read

When working with databases in Rails, it’s common to allow nullable columns or to change the null constraint of a column.

For example, to set a NOT NULL constraint on the email column in the users table run:

$ rails generate migration change_column_null_for_email
      invoke  active_record
      create    db/migrate/20240325142034_change_column_null_for_email.rb

The above command will generate an empty migration

class ChangeColumnNullForEmail < ActiveRecord::Migration[7.1]
  def change
  end
end

We need to modify it to:

class ChangeColumnNullForEmail < ActiveRecord::Migration[7.1]
  def change
    change_column_null(:users, :email, false)
  end
end

This migration will update the schema to enforce the presence of email addresses for users.

Syntax

change_column_null(table_name, column_name, null, default = nil)

NOTE:

The null flag indicates whether the value can be NULL. For example

change_column_null(:users, :email, false)

User email cannot be NULL (adds NOT NULL constraint)

change_column_null(:users, :email, true)

Allows user email to be NULL (drops the NOT NULL constraint).

References

You May Also Enjoy