Question

I used a migration in ruby to create these tables together with a model.

I have a Table Information and a Table Detail, each entry in the information table can have one association in the detail table.

So i created them with:

create_table :details do |t|
      t.integer :id
      t.string :Bezeichnung
      t.binary :Koordinaten
    end

 create_table :informations do |t|
      t.integer :id
      t.integer :DetailID
      t.integer :Longitude
      t.integer :Latitude
    end

In my Information Table i got a DetailID which should Reference to the id of the Detail table.

Now i did:

ALTER TABLE informations
      ADD CONSTRAINT fk_informations_details
      FOREIGN KEY (DetailID)
      REFERENCES details(id)

Is this correct? Have i set the FOREIGN KEY correct? Or do i have to put the foreign key in the other table!?

Because i want to use in my Information Model following:

has_one :detail, :foreign_key => 'DetailID'

And in the Detail Model following:

belongs_to :main

Answer 1

Some notes:

1. Perform all kinds of alterations on the database using migrations, never do them by hand.
2. Use Ruby on Rails naming convention whenever possible. This means using detail_id instead of DetailID
3. Your associations are wrong.

If Information has_one :detail, Ruby on Rails will look for an entity with a matching information_id in the details table.

In your model, it is the other way around – the Information contains a detail_id. In other words Ruby on Rails would specify this as Information belongs_to :detail and Detail has_one :information.