Nested records using join Rails

Question

I have these models

class Car < ApplicationRecord
  has_many :car_locations ,:dependent=>:destroy
  has_many :rides,:dependent=>:destroy
end

class CarLocation < ApplicationRecord
  belongs_to :car
end

class Ride < ApplicationRecord
  belongs_to :car
end

There is a status attribute in Ride Model of boolean type.

Now I want those CarLocations whose car rides status is false or don't have any car ride with in minimum complexity.

Andrey Deineko · Accepted Answer · 2016-12-08 13:20:57Z

2

I want those Car Locations whose car rides status is false

CarLocation.joins(car: :rides).where(rides: { status: false })

or don't have any car ride

CarLocation.includes(car: :rides)
           .where(rides: { id: nil })
           .references(:rides)

Combining both together:

CarLocation.includes(car: :rides)
           .where('rides.status = false OR rides.id IS NULL')
           .references(:rides)

edited Dec 8, 2016 at 13:20

answered Dec 8, 2016 at 12:58

Andrey Deineko

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10 Comments

Jai Kumar Rajput Over a year ago

This cause error : > ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR: missing FROM-clause entry for table "rides" LINE 1: ...ECT "car_locations".* FROM "car_locations" WHERE (rides.stat...

Andrey Deineko Over a year ago

@JaiKumarRajput according to your description in OP this is impossible. I mean, this should work with the set up you've shown

Jai Kumar Rajput Over a year ago

if I replace includes with joins then this works perfect. but using includes... facing error. Please correct me if I'm doing somthing wrong

dp7 Over a year ago

CarLocation.includes(car: :rides).where('rides.status = false OR rides.id IS NULL').references(:rides) - does this work ?

Andrey Deineko Over a year ago

@dp7 super nice catch! Thanks! I'm on Rails5 and did not have to use references (worked without it)

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