Rails add_index missing when running GENERATE command

Question

Since I am new to Rails, I am following this 'getting started' guide on rails website.

On section 6.1 Generating a Model, I should run rails generate model Comment commenter:string body:text post:references to get a comment model.

Supposedly, this is what should be included in the migration file:

class CreateComments < ActiveRecord::Migration
   def change
     create_table :comments do |t|
       t.string :commenter
       t.text :body
       t.references :post

       t.timestamps
     end

     add_index :comments, :post_id
   end
end

But in my migration file, I have everything but this line add_index :comments, :post_id. Instead, I have index:true following the t.references :post

I can't seem to find an explanation to this, can anyone explain to me what is going on here? Because later on I need to use :post_id, but in my version of migration, it is not clearly declared. I am very confused.

post your exact migration file

Siva
– Siva

2013-12-26 12:35:11 +00:00
Commented Dec 26, 2013 at 12:35 — Siva
– Siva, Commented Dec 26, 2013 at 12:35

edikgat · Accepted Answer · 2013-12-26 16:57:53Z

2

class CreateComments < ActiveRecord::Migration
  def change
     create_table :comments do |t|
       t.string :commenter
       t.text :body
       t.references :post

       t.timestamps
     end

     add_index :comments, :post_id
  end
end

and

class CreateComments < ActiveRecord::Migration
  def change
     create_table :comments do |t|
       t.string :commenter
       t.text :body
       t.references :post, index: true

       t.timestamps
     end

  end
end

will do same things, both of them will add index to post_id column

also you can later add index to any column any column that you want to add to your model like

$ rails generate migration AddPartNumberToProducts part_number:string:index

that will produce this code:

class AddPartNumberToProducts < ActiveRecord::Migration
  def change
    add_column :products, :part_number, :string
    add_index :products, :part_number
  end
end

answered Dec 26, 2013 at 16:57

edikgat

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1 Comment

donkey Over a year ago

Good to know, but is that a new feature of using "index:true"?

HarsHarI · Accepted Answer · 2013-12-26 12:36:06Z

0

in above code if you want to create index for post_id then write it as t.integer :post_id else you can try this add_index :comments, :post

answered Dec 26, 2013 at 12:36

HarsHarI

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