Rails: ActiveRecord Query for has_many :through model

Question

How to query for Companies with a certain Branch in a "has_many :through" relationship?

  #company.rb
  has_many :branch_choices
  has_many :branches, :through => :branch_choices

"Find all companies with Branch ID 3"

RocketR · Accepted Answer · 2013-07-12T10:30:47.617

16

Company.includes(:branches).where(:branches => {:id => 3})

or

Branch.find(3).companies

UPDATE Actually, there's one downside to the first snippet: it eagerly loads branches along with the companies. To avoid this overhead you may consider using a left join:

Company.
  joins("LEFT JOIN `branch_choices` ON `branch_choices`.`company_id` = `companies`.`id`").
  where(:branch_choices => {:branch_id => 3})

edited Jul 12 '13 at 10:30

answered Jul 31 '11 at 17:01

RocketR

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In addition, how would the first line look like as a Scope? – David Jul 31 '11 at 17:27
1

`scope :filter_by_branch, lambda{|branch_id| includes(:branches).where(:branches => {:id => branch_id})` – RocketR Jul 31 '11 at 17:36

score 0 · Answer 2 · answered Apr 28 '23 at 08:21

0

The following should do the trick and avoids extra queries:

Company.joins(:branches).where(:branches => {:id => 3})

answered Apr 28 '23 at 08:21

wandering-tales

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Rails: ActiveRecord Query for has_many :through model

2 Answers2