Rails includes with eager loading => nested models not in to_json version?

Question

I have a class TwitterUser that has many TwitterLists

class TwitterUser < ActiveRecord::Base    
    has_many :twitter_lists, :dependent => :destroy
end

When I do:

user = TwitterUser.includes(:twitter_lists).find(12615489)

then:

lists = user.twitter_lists

it eagerly loads the twitter lists for that user in the first "find", so it doesn't run a query when I do user.twitter_lists (this is expected).

However when I try to convert the user to JSON like: user.to_json

I don't see the nested association "twitter_lists" anywhere in the JSON. Even though I used eager loading. Why is this? And how can I make it appear in the JSON?

Frederick Cheung · Accepted Answer · 2013-05-18 15:17:58Z

1

To include the association in the output of to_json you need to pass :include => :twitter_lists to to_json

There is no connection between the associations that are eager loaded and the associations that are included in the output of to_json - the two are completely independant.

answered May 18, 2013 at 15:17

Frederick Cheung

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Community · Accepted Answer · 2017-05-23 11:57:22Z

0

Check this answer May be this is what you need

Rails find method - select columns from ":include" table parameter

includes is just for eager loading. Which means it is cached somewhere but not actually returned

edited May 23, 2017 at 11:57

CommunityBot

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answered May 18, 2013 at 2:05

shishirmk

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