CODEWITHSUNDEEP
ruby-on-railsrubyactive-model-serializers
Cheyne
Cheyne

Reputation: 2119

Select Attributes From Rails Nested Includes Association With ActiveModelSerializer?

So i've been struggling with this for a few hours and im hoping someone can help.

I have a 3 level relationship, List, Page & App.
A List has_many Pages A Page belongs_to List and can optionally belongs_to an App. App has_many Pages

With a query like this

@account.lists.includes(pages: :app)

Everything works fine, I have no N+1 queries, and its all being eager loaded correctly

Eg

List Load (3.0ms)  SELECT `lists`.* FROM `rotations` WHERE `lists`.`account_id` = 1
Page Load (2.5ms)  SELECT `pages`.* FROM `pages` WHERE `pages`.`list_id` IN (13, 17, 18)
App Load (2.0ms)  SELECT `apps`.* FROM `apps` WHERE `apps`.`id` IN (6, 9, 15)

My problem is that all these statements are SELECT * FROM although the Apps records in particular are quite heavy. There can be entire HTML documents in a column named "content"

I really need to be able to only SELECT apps.id, apps.name FROMapps ....`. So im not loading these full objects into memory only just discard it all a moment later when I render only the ID and names.

I would perform this manually, although I can't seem to get this working with ActiveModelSerializers.

My serializers are pretty standard. A List that has_many :pages and a page that belongs_to :app.

How can I only pull select attributes from one of my nested associations? Im pretty sure I can use joins() but im not sure how that works with my serializers?

Cheers

Upvotes: 0

Views: 1535

Answers (1)

Beartech
Beartech

Reputation: 6411

Hmmm.. trying to test this on an app with similar associations. I think something like this might work:

@account.lists.includes(pages: :app).pluck("apps.id", "apps.name")

This will do a LEFT OUTER JOIN on the associations.

@account.lists.joins(pages: :app).pluck("apps.id", "apps.name")

will do INNER JOINS. Not sure what you are looking for exactly without a lot more info on your data structures and example output.

Upvotes: 1

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