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. I've googled around but I can't find how to write a migration which adds not null to an existing column.
TIA.
您还可以使用change_column_null :
change_column_null :table_name, :column_name, false
For Rails 4+, nates' answer (using change_column_null ) is better.
Pre-Rails 4, try change_column .
1) FIRST: Add column with default value
2) THEN: Remove default value
add_column :orders, :items, :integer, null: false, default: 0
change_column :orders, :items, :integer, default: nil
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
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.
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