How to add database level foreign key in the migration file in rails 4.2?

Question

I have gone through some of similar question people asked but couldn't find the appropriate solution for it. I have also seen some people using this method - add_foreign_key

 class CreateTaskLists < ActiveRecord::Migration
  def change
    create_table :task_lists do |t|
      t.string :name
      t.references :user
      t.timestamps
    end
    add_foreign_key :task_lists, :users
  end
end

but it is throwing undefined method error.

undefined method `add_foreign_key' for 
#<CreateTaskLists:0x007ffe9a5cd578>
/Users/sushilkumar/.rvm/gems/ruby-2.2.3/gems/
activerecord-4.0.0/lib/active_record/
migration.rb:624:in `block in method_missing'

How to add foreign key in rails migration with different table name I don't know, How does this work for them?

What is the error? Please update it in your question. – Pavan Oct 08 '15 at 07:16 — Pavan, Oct 08 '15 at 07:16

score 2 · Answer 1 · edited Oct 08 '15 at 11:23

2

You can simply try this way using references

class CreateTaskLists < ActiveRecord::Migration
  def change
    create_table :task_lists do |t|
      t.string :name
      t.references :user, index: true
      t.timestamps
    end
    add_foreign_key :task_lists, :users
  end
end

edited Oct 08 '15 at 11:23

sushilprj

2,203
1
14
19

answered Oct 08 '15 at 07:26

Rajarshi Das

11,778
6
46
74

I have updated the migration but it is still throwing error. Is there any gem required to enable add_foreign_key method? – sushilprj Oct 08 '15 at 08:00
http://api.rubyonrails.org/v4.2.0/classes/ActiveRecord/ConnectionAdapters/SchemaStatements.html#method-i-add_foreign_key – Rajarshi Das Oct 08 '15 at 08:27
Thanks Rajarshi, It was my mistake. I was using rails 4.0.0 version. Now it is working .. :) – sushilprj Oct 08 '15 at 09:43

score 1 · Answer 2 · answered Oct 08 '15 at 08:08

1

class CreateTaskLists < ActiveRecord::Migration
  def change
    create_table :task_lists do |t|
      t.string :name
      t.references :user, index: true
      t.timestamps
    end
    add_foreign_key :task_lists, :users
  end
end

try this

answered Oct 08 '15 at 08:08

Vrushali Pawar

3,753
1
13
22

score 1 · Answer 3 · answered Oct 08 '15 at 08:27

Did you meant to reference the table User and not Users? If so, you must use the singular (:user) when making a reference:

class CreateTaskLists < ActiveRecord::Migration
 def change
   create_table :task_lists do |t|
     t.string :name
     t.references :user
     t.timestamps
   end
   add_foreign_key :task_lists, :users
 end

end

score 0 · Answer 4 · edited Oct 08 '15 at 10:43

0

Hope this will work for you.

class CreateTaskLists < ActiveRecord::Migration
  def change
    create_table :task_lists do |t|
      t.string :name
      t.references :user
      t.timestamps
    end
    add_foreign_key :users, :task_lists
  end
end

edited Oct 08 '15 at 10:43

sushilprj

2,203
1
14
19

answered Oct 08 '15 at 10:39

CreativePS

1,105
7
15

How to add database level foreign key in the migration file in rails 4.2?

4 Answers4