CODEWITHSUNDEEP
ruby-on-railsrubypostgresqlruby-on-rails-5
Sylar
Sylar

Reputation: 12092

How to tell a model has an empty relation

There maybe an answer for this but I might not be searching with the correct words. How to tell my model has an association object? Makes sense?

#Foo Model:
 has_one :bar

#User Model:
 has_many :foos

User.first.foos.bar #=> {object}

Basically what I want is, give me all of foos that has no bar. Is this possible?

Instead of adding a table onto foo: has_bar: <boolean>, then:

User.first.foos.where(has_bar: false)

Edit:

This maybe a duplicate post based on Albin's answer. But it still works for Rails 5.

Upvotes: 1

Views: 91

Answers (2)

Albin
Albin

Reputation: 3032

If you read the answers in this question you will find multiple ways of doing it: Want to find records with no associated records in Rails 3

The way I would do it is:

User.first.foos.includes(:bar).where(bars: { foo_id: nil } )

Upvotes: 1

fabriciofreitag
fabriciofreitag

Reputation: 2883

User.first.foos.select { |foo| foo.include(:bar) && foo.bar.id.nil? }

Upvotes: 1

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