Rails association - how to add the 'has_many' object to the 'owner'

Question

In my app, a user has many score_cards and a score_card belongs to a user

The question is, whenever I create a new score_card, ie, ScoreCardsController.create gets called, how do I add this newly created score_card to the current_user (I'm using devise, so current_user is a valid User object).

grzuy · Accepted Answer · 2016-05-06T02:07:58.903

71

current_user.score_cards << score_card

OR

score_card.user = current_user
score_card.save

edited May 06 '16 at 02:07

answered Apr 27 '11 at 03:40

grzuy

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I personally prefer the first one, but it is up to you :) – grzuy Oct 13 '12 at 20:34
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I believe these are not actually equivalent because `<<` will save the association (without having to explicitly call `User#save`). – David Tuite Dec 06 '13 at 10:49
You do not need to call current_user.save. You can just call "current_user.score_cards << score_card" – etc Dec 08 '13 at 23:33
I would upvote this answer if the first solution didn't include a redundant save. – mwfearnley May 05 '16 at 13:52
... And indeed now have. :) – mwfearnley May 06 '16 at 13:46

score 13 · Answer 2 · answered Apr 27 '11 at 08:47

13

Use the association builder method:

current_user.score_cards.build(params[:score_card])

Alternatively to build you can use create or create! if you don't care about the validations in the controller.

answered Apr 27 '11 at 08:47

Ryan Bigg

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score 11 · Answer 3 · answered Jul 22 '15 at 17:17

11

I'm going to throw this out there in case anyone is looking for a way to add multiple objects to an associated object:

score_cards = ScoreCard.all
current_user.score_cards << score_cards

No need to current_user.save

answered Jul 22 '15 at 17:17

Abram

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Thanks for making note of this! I've always been doing an unnecessary save afterward. – Luke Ehresman Jan 19 '16 at 15:38

Rails association - how to add the 'has_many' object to the 'owner'

3 Answers3