Ruby on Rails build makes id nil

Question

In my project, a user has a hotel, and each hotel has room types associated with it. Briefly, the models are

 class User < ActiveRecord::Base
     has_many :hotels

 class Hotel < ActiveRecord::Base
      belongs_to :user
      has_many :roomtypes

 class Roomtype < ActiveRecord::Base
    attr_accessible :maxguests, :name
    belongs_to :hotel

If I do the commands:

 @user = User.find(1)
 @user.hotels.find(1).roomtypes.build(name: "something", maxguests: "2")

The console returns:

    #<Roomtype id: nil, name: "something", maxguests: 2, created_at: nil, updated_at: nil, hotel_id: 1>

For some reason, the Roomtype id and the timestamps are nil. Any ideas why?

score 7 · Accepted Answer · edited Sep 12 '12 at 01:27

7

You have built the roomtype (which creates a new instance of the object), but you not saved it yet. You have to explicitly save roomtype for it to go into the db (and thus get an id).

Instead of build use create or create! to accomplish this with a single method call

edited Sep 12 '12 at 01:27

Taryn East

27,486
9
86
108

answered Sep 11 '12 at 13:46

Amar

6,874
4
25
23

See http://stackoverflow.com/questions/403671/the-differences-between-build-create-and-create-and-when-should-they-be-us for a more detailed description of these methods. – gregates Sep 11 '12 at 13:59

score 3 · Answer 2 · answered Sep 11 '12 at 13:46

3

Replace build with create and you'll have your persisted object with id and timestamp.

Would not make sense to have this before.

answered Sep 11 '12 at 13:46

apneadiving

114,565
26
219
213

Ruby on Rails build makes id nil

2 Answers2