Why did Rails 5 changed “index” to “foreign key”?

If you had this in Rails 4:

t.references :event, index: true

Now you could use foreign_key instead of index in Rails 5. I don't quite understand WHY they decided to do this, since the functionality remains the same, what you're adding is an INDEX, not a FOREIGN KEY to that column.

edited Sep 29 '16 at 13:31

Ajay Barot

1,43111833

asked Sep 29 '16 at 12:11

anemaria20

537722

3

I honestly don't understand your question, the index option adds a database index, the foreign key one adds a database foreign key.

– j-dexx
Sep 29 '16 at 12:13

add a comment |

If you had this in Rails 4:

t.references :event, index: true

edited Sep 29 '16 at 13:31

Ajay Barot

1,43111833

asked Sep 29 '16 at 12:11

anemaria20

537722

3

I honestly don't understand your question, the index option adds a database index, the foreign key one adds a database foreign key.

– j-dexx
Sep 29 '16 at 12:13

add a comment |

If you had this in Rails 4:

t.references :event, index: true

edited Sep 29 '16 at 13:31

Ajay Barot

1,43111833

asked Sep 29 '16 at 12:11

anemaria20

537722

If you had this in Rails 4:

t.references :event, index: true

ruby-on-rails foreign-keys primary-key ruby-on-rails-5

edited Sep 29 '16 at 13:31

Ajay Barot

1,43111833

asked Sep 29 '16 at 12:11

anemaria20

537722

edited Sep 29 '16 at 13:31

Ajay Barot

1,43111833

asked Sep 29 '16 at 12:11

anemaria20

537722

edited Sep 29 '16 at 13:31

Ajay Barot

1,43111833

edited Sep 29 '16 at 13:31

Ajay Barot

1,43111833

edited Sep 29 '16 at 13:31

Ajay Barot

1,43111833

asked Sep 29 '16 at 12:11

anemaria20

537722

asked Sep 29 '16 at 12:11

anemaria20

537722

asked Sep 29 '16 at 12:11

anemaria20

537722

3

I honestly don't understand your question, the index option adds a database index, the foreign key one adds a database foreign key.

– j-dexx
Sep 29 '16 at 12:13

add a comment |

3

I honestly don't understand your question, the index option adds a database index, the foreign key one adds a database foreign key.

– j-dexx
Sep 29 '16 at 12:13

I honestly don't understand your question, the index option adds a database index, the foreign key one adds a database foreign key.

– j-dexx
Sep 29 '16 at 12:13

add a comment |

3 Answers
3

active

oldest

votes

In Rails 5 - when we reference a model, index on the foreign_key is automatically created.

Migration API has changed in Rails 5 -

Rails 5 has changed migration API because of which even though null: false options is not passed to timestamps when migrations are run then not null is automatically added for timestamps.

Similarly, we want indexes for referenced columns in almost all cases. So Rails 5 does not need references to have index: true. When migrations are run then index is automatically created.

As an example - (Copying from http://blog.bigbinary.com/2016/03/01/migrations-are-versioned-in-rails-5.html)

When you run rails g model Task user:references

Rails 4 would generate

class CreateTasks < ActiveRecord::Migration

  def change

    create_table :tasks do |t|

      t.references :user, index: true, foreign_key: true

      t.timestamps null: false

    end

  end

end

And rails 5 would generate

class CreateTasks < ActiveRecord::Migration[5.0]

  def change

    create_table :tasks do |t|

      t.references :user, foreign_key: true

      t.timestamps

    end

  end

end

answered Sep 29 '16 at 12:23

Pramod Solanky

1,3581116

Very well detailled answer. BUT, what if for whatever reason, I don't want the reference to be indexed? Or was it still indexed implicitly in Rails 4 even if I only have t.references :user, foreign_key: true ? --- And now, I wonder why they didn't even omit foreign_key: true too.

– Asme Just
Jul 29 '17 at 6:24

add a comment |

The index and foreign_key are different concepts, even if in Rails 5. So it's wrong to say the rails 5 changed “index” to “foreign key”.

The change from Rails 4 to Rails 5 is that the index option defaults to true, so you don't need to set it explicitly.

Method add_reference in rails 4.2.5

:index

Add an appropriate index. Defaults to false.

Method add_reference in rails 5.2

:index

Add an appropriate index. Defaults to true. See add_index for usage of this option.

That's why when you generate the references in rails 5 migration, you didn't see the index: true, because it's default.

edited Jan 2 at 21:30

Meekohi

6,68643948

answered Jun 6 '18 at 23:28

Stephen

1,499918

add a comment |

foreign_key and index are completely different things (as you may judge from their names).

So nothing is being changed, you still can use two.

You can check out these docs for some more info on establishing associations in migrations.

answered Sep 29 '16 at 12:14

Andrey Deineko

40.5k85695

add a comment |

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3 Answers
3

active

oldest

votes

3 Answers
3

active

oldest

votes

In Rails 5 - when we reference a model, index on the foreign_key is automatically created.

Migration API has changed in Rails 5 -

Rails 5 has changed migration API because of which even though null: false options is not passed to timestamps when migrations are run then not null is automatically added for timestamps.

Similarly, we want indexes for referenced columns in almost all cases. So Rails 5 does not need references to have index: true. When migrations are run then index is automatically created.

As an example - (Copying from http://blog.bigbinary.com/2016/03/01/migrations-are-versioned-in-rails-5.html)

When you run rails g model Task user:references

Rails 4 would generate

class CreateTasks < ActiveRecord::Migration

  def change

    create_table :tasks do |t|

      t.references :user, index: true, foreign_key: true

      t.timestamps null: false

    end

  end

end

And rails 5 would generate

class CreateTasks < ActiveRecord::Migration[5.0]

  def change

    create_table :tasks do |t|

      t.references :user, foreign_key: true

      t.timestamps

    end

  end

end

answered Sep 29 '16 at 12:23

Pramod Solanky

1,3581116

Very well detailled answer. BUT, what if for whatever reason, I don't want the reference to be indexed? Or was it still indexed implicitly in Rails 4 even if I only have t.references :user, foreign_key: true ? --- And now, I wonder why they didn't even omit foreign_key: true too.

– Asme Just
Jul 29 '17 at 6:24

add a comment |

In Rails 5 - when we reference a model, index on the foreign_key is automatically created.

Migration API has changed in Rails 5 -

Rails 5 has changed migration API because of which even though null: false options is not passed to timestamps when migrations are run then not null is automatically added for timestamps.

Similarly, we want indexes for referenced columns in almost all cases. So Rails 5 does not need references to have index: true. When migrations are run then index is automatically created.

As an example - (Copying from http://blog.bigbinary.com/2016/03/01/migrations-are-versioned-in-rails-5.html)

When you run rails g model Task user:references

Rails 4 would generate

class CreateTasks < ActiveRecord::Migration

  def change

    create_table :tasks do |t|

      t.references :user, index: true, foreign_key: true

      t.timestamps null: false

    end

  end

end

And rails 5 would generate

class CreateTasks < ActiveRecord::Migration[5.0]

  def change

    create_table :tasks do |t|

      t.references :user, foreign_key: true

      t.timestamps

    end

  end

end

answered Sep 29 '16 at 12:23

Pramod Solanky

1,3581116

Very well detailled answer. BUT, what if for whatever reason, I don't want the reference to be indexed? Or was it still indexed implicitly in Rails 4 even if I only have t.references :user, foreign_key: true ? --- And now, I wonder why they didn't even omit foreign_key: true too.

– Asme Just
Jul 29 '17 at 6:24

add a comment |

In Rails 5 - when we reference a model, index on the foreign_key is automatically created.

Migration API has changed in Rails 5 -

Rails 5 has changed migration API because of which even though null: false options is not passed to timestamps when migrations are run then not null is automatically added for timestamps.

Similarly, we want indexes for referenced columns in almost all cases. So Rails 5 does not need references to have index: true. When migrations are run then index is automatically created.

As an example - (Copying from http://blog.bigbinary.com/2016/03/01/migrations-are-versioned-in-rails-5.html)

When you run rails g model Task user:references

Rails 4 would generate

class CreateTasks < ActiveRecord::Migration

  def change

    create_table :tasks do |t|

      t.references :user, index: true, foreign_key: true

      t.timestamps null: false

    end

  end

end

And rails 5 would generate

class CreateTasks < ActiveRecord::Migration[5.0]

  def change

    create_table :tasks do |t|

      t.references :user, foreign_key: true

      t.timestamps

    end

  end

end

answered Sep 29 '16 at 12:23

Pramod Solanky

1,3581116

In Rails 5 - when we reference a model, index on the foreign_key is automatically created.

Migration API has changed in Rails 5 -

Rails 5 has changed migration API because of which even though null: false options is not passed to timestamps when migrations are run then not null is automatically added for timestamps.

Similarly, we want indexes for referenced columns in almost all cases. So Rails 5 does not need references to have index: true. When migrations are run then index is automatically created.

As an example - (Copying from http://blog.bigbinary.com/2016/03/01/migrations-are-versioned-in-rails-5.html)

When you run rails g model Task user:references

Rails 4 would generate

class CreateTasks < ActiveRecord::Migration

  def change

    create_table :tasks do |t|

      t.references :user, index: true, foreign_key: true

      t.timestamps null: false

    end

  end

end

And rails 5 would generate

class CreateTasks < ActiveRecord::Migration[5.0]

  def change

    create_table :tasks do |t|

      t.references :user, foreign_key: true

      t.timestamps

    end

  end

end

answered Sep 29 '16 at 12:23

Pramod Solanky

1,3581116

answered Sep 29 '16 at 12:23

Pramod Solanky

1,3581116

answered Sep 29 '16 at 12:23

Pramod Solanky

1,3581116

answered Sep 29 '16 at 12:23

Pramod Solanky

1,3581116

Very well detailled answer. BUT, what if for whatever reason, I don't want the reference to be indexed? Or was it still indexed implicitly in Rails 4 even if I only have t.references :user, foreign_key: true ? --- And now, I wonder why they didn't even omit foreign_key: true too.

– Asme Just
Jul 29 '17 at 6:24

add a comment |

Very well detailled answer. BUT, what if for whatever reason, I don't want the reference to be indexed? Or was it still indexed implicitly in Rails 4 even if I only have t.references :user, foreign_key: true ? --- And now, I wonder why they didn't even omit foreign_key: true too.

– Asme Just
Jul 29 '17 at 6:24

Very well detailled answer. BUT, what if for whatever reason, I don't want the reference to be indexed? Or was it still indexed implicitly in Rails 4 even if I only have t.references :user, foreign_key: true ? --- And now, I wonder why they didn't even omit foreign_key: true too.

– Asme Just
Jul 29 '17 at 6:24

add a comment |

The index and foreign_key are different concepts, even if in Rails 5. So it's wrong to say the rails 5 changed “index” to “foreign key”.

The change from Rails 4 to Rails 5 is that the index option defaults to true, so you don't need to set it explicitly.

Method add_reference in rails 4.2.5

:index

Add an appropriate index. Defaults to false.

Method add_reference in rails 5.2

:index

Add an appropriate index. Defaults to true. See add_index for usage of this option.

That's why when you generate the references in rails 5 migration, you didn't see the index: true, because it's default.

edited Jan 2 at 21:30

Meekohi

6,68643948

answered Jun 6 '18 at 23:28

Stephen

1,499918

add a comment |

The index and foreign_key are different concepts, even if in Rails 5. So it's wrong to say the rails 5 changed “index” to “foreign key”.

The change from Rails 4 to Rails 5 is that the index option defaults to true, so you don't need to set it explicitly.

Method add_reference in rails 4.2.5

:index

Add an appropriate index. Defaults to false.

Method add_reference in rails 5.2

:index

Add an appropriate index. Defaults to true. See add_index for usage of this option.

That's why when you generate the references in rails 5 migration, you didn't see the index: true, because it's default.

edited Jan 2 at 21:30

Meekohi

6,68643948

answered Jun 6 '18 at 23:28

Stephen

1,499918

add a comment |

The index and foreign_key are different concepts, even if in Rails 5. So it's wrong to say the rails 5 changed “index” to “foreign key”.

The change from Rails 4 to Rails 5 is that the index option defaults to true, so you don't need to set it explicitly.

Method add_reference in rails 4.2.5

:index

Add an appropriate index. Defaults to false.

Method add_reference in rails 5.2

:index

Add an appropriate index. Defaults to true. See add_index for usage of this option.

That's why when you generate the references in rails 5 migration, you didn't see the index: true, because it's default.

edited Jan 2 at 21:30

Meekohi

6,68643948

answered Jun 6 '18 at 23:28

Stephen

1,499918

The index and foreign_key are different concepts, even if in Rails 5. So it's wrong to say the rails 5 changed “index” to “foreign key”.

The change from Rails 4 to Rails 5 is that the index option defaults to true, so you don't need to set it explicitly.

Method add_reference in rails 4.2.5

:index

Add an appropriate index. Defaults to false.

Method add_reference in rails 5.2

:index

Add an appropriate index. Defaults to true. See add_index for usage of this option.

That's why when you generate the references in rails 5 migration, you didn't see the index: true, because it's default.

edited Jan 2 at 21:30

Meekohi

6,68643948

answered Jun 6 '18 at 23:28

Stephen

1,499918

edited Jan 2 at 21:30

Meekohi

6,68643948

edited Jan 2 at 21:30

Meekohi

6,68643948

edited Jan 2 at 21:30

Meekohi

6,68643948

answered Jun 6 '18 at 23:28

Stephen

1,499918

answered Jun 6 '18 at 23:28

Stephen

1,499918

answered Jun 6 '18 at 23:28

Stephen

1,499918

add a comment |

foreign_key and index are completely different things (as you may judge from their names).

So nothing is being changed, you still can use two.

You can check out these docs for some more info on establishing associations in migrations.

answered Sep 29 '16 at 12:14

Andrey Deineko

40.5k85695

add a comment |

foreign_key and index are completely different things (as you may judge from their names).

So nothing is being changed, you still can use two.

You can check out these docs for some more info on establishing associations in migrations.

answered Sep 29 '16 at 12:14

Andrey Deineko

40.5k85695

add a comment |

foreign_key and index are completely different things (as you may judge from their names).

So nothing is being changed, you still can use two.

You can check out these docs for some more info on establishing associations in migrations.

answered Sep 29 '16 at 12:14

Andrey Deineko

40.5k85695

foreign_key and index are completely different things (as you may judge from their names).

So nothing is being changed, you still can use two.

You can check out these docs for some more info on establishing associations in migrations.

answered Sep 29 '16 at 12:14

Andrey Deineko

40.5k85695

answered Sep 29 '16 at 12:14

Andrey Deineko

40.5k85695

answered Sep 29 '16 at 12:14

Andrey Deineko

40.5k85695

answered Sep 29 '16 at 12:14

Andrey Deineko

40.5k85695

add a comment |

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