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ruby-on-railsdatabasemigrationconstraintsnotnull
David Robertson
David Robertson

Reputation: 1829

Ruby on Rails: How do I add a not null constraint to an existing column using a migration?

In my Rails (3.2) app, I have a bunch of tables in my database but I forgot to add a few not null constraints. How can I write a migration which adds not null to an existing column?

Upvotes: 150

Views: 73677

Answers (5)

rndrfero
rndrfero

Reputation: 322

  1. Add column with default value

  2. Remove default value

add_column :orders, :items, :integer, null: false, default: 0
change_column :orders, :items, :integer, default: nil

Upvotes: 13

Thien Ngan
Thien Ngan

Reputation: 104

In my approach, I add NOT NULL constraint to columns i need in my existing migrated migration. After that, I reset all my migrations by using this command:

rake db:migrate:reset

This will drop the database, create it again and run all the migrations. You can check your changes in schema.rb.

If you have few columns in simple migrations, you can use this approach.

Upvotes: 0

Dan Wich
Dan Wich

Reputation: 4943

For Rails 4+, nates' answer (using change_column_null) is better.

Pre-Rails 4, try change_column.

Upvotes: 97

Manjunath Reddy
Manjunath Reddy

Reputation: 1217

If you are using it on a new create migration script/schema here is how we can define it

class CreateUsers < ActiveRecord::Migration[5.2]
  def change
    create_table :users do |t|
    t.string :name, null: false     # Notice here, NOT NULL definition
    t.string :email, null: false
    t.string :password, null: false
    t.integer :created_by
    t.integer :updated_by 

    t.datetime :created_at
    t.datetime :updated_at, default: -> { 'CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP' }
   end
  end
end

Upvotes: 3

nates
nates

Reputation: 8462

You can also use change_column_null:

change_column_null :table_name, :column_name, false

Upvotes: 307

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