Add an array column in Rails

Question

How do you declare an array column in Rails?

Detail

I have the following model

rails generate model User address:text 

but I want a model which can store multiple addresses per user. The following declaration gives me an error

rails generate model User address[]:text  

How do you declare an array column in Rails?

Answer 1

You can use following steps

rails g migration add_subjects_to_book subjects:text 

And the migration file:

class AddSubjectsToBook < ActiveRecord::Migration   def change     add_column :books, :subjects, :text, array: true, default: []   end end 

We can check it now:

2.1.2 :001 > b = Book.create    (0.2ms)  BEGIN   SQL (2.0ms)  INSERT INTO "books" ("created_at", "updated_at") VALUES ($1, $2) RETURNING "id"  [["created_at", "2014-10-17 08:21:17.870437"], ["updated_at", "2014-10-17 08:21:17.870437"]]    (0.5ms)  COMMIT  => #<Book id: "39abef75-56af-4ad5-8065-6b4d58729ee0", title: nil, created_at: "2014-10-17 08:21:17", updated_at: "2014-10-17 08:21:17", description: {}, metadata: {}, subjects: []>  2.1.2 :002 > b.subjects.class  => Array 

If you want to add array while creating table you can do as follows

create_table :products do |t|   t.string :name, null: false   t.references :category, null: false   t.text :tags, array: true, default: [] end 

Note: array column is supported by PostgreSQL