CODEWITHSUNDEEP
ruby-on-railsdatabase-designrails-migrations
cengo
cengo

Reputation: 151

What is belongs_to creates in rails migrations and in the database structure?

I'm confused about belongs_to and foreign key in rails. When we use belongs_to in rails migrations, it seems like it creates a foreign key on the child table that we can access from the parent table. However, in the rails documentation, there is a situation that uses both in one column.

create_table :accounts do |t|
  t.belongs_to :supplier, index: { unique: true }, foreign_key: true
  # ...
end

Can somebody explain this situation and explain the what belongs_to and foreign_key: true exactly does?

Upvotes: 0

Views: 32

Answers (1)

Danil Speransky
Danil Speransky

Reputation: 30453

t.belongs_to :supplier adds supplier_id to accounts.

index: { unique: true } creates a database index for the column.

foreign_key: true creates a foreign key constraint for the column.

I recommend you to read Active Record Migrations — Ruby on Rails Guides.

Indexes speed up data retrieval operations.

Foreign keys help to maintain referential integrity.

Upvotes: 1

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