CODEWITHSUNDEEP
ruby-on-railsactiverecord
karimmt
karimmt

Reputation: 21

Rails Active Records Multiple joins

Is there any way I can get this SQL query by using ActiveRecord query syntax?

select t1.*
from
  t1
  join t2 on t1.id = t2.t1_id
  join t3 on t2.id = t3.t2_id
  join t4 on t3.id = t4.t3_id
  join t5 on t4.id = t5.t4_id
where t5.id = 5;

Upvotes: 1

Views: 1178

Answers (2)

D-side
D-side

Reputation: 9495

The problem with your query is that you're based off the database tables named not per Rails convention of having plural table names. I can provide an example similar to yours, it looks like this:

Universe.joins(
  galaxies: {
    stars: {
      planets: {
          molecules: :atoms
      }
    }
  }
).where(atoms: {id: 5})

And this query assumes you have models:

  • Universe that has_many :galaxies
  • Galaxy that has_many :stars and belongs_to :universe (as such, has universe_id)
  • Star that has_many :planets and belongs_to :galaxy
  • Planet that has_many :molecules and belongs_to :star
  • Molecule that has_many :atoms and belongs_to :planet
  • Atom... just belongs_to :molecule

Upvotes: 1

errata
errata

Reputation: 26972

I would start by reading this: http://guides.rubyonrails.org/association_basics.html and creating tables with names that somehow represent the data you are working with. Create migrations model classes with the proper associations and come back and update your question.

Upvotes: 0

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