How to chain joins in Sequel as in ActiveRecord

Question

I have a model "MyModel" with the following relationships:

Class MyModel

    #if MyModel < ActiveRecord::Base
    has_one a
    has_one b

    #if MyModel < Sequel::Model
    many_to_one a
    many_to_one b

end

With ActiveRecord:

MyModel.joins(:a, :b)

or

MyModel.joins(:a).joins(:b)

gives the following SQL:

SELECT * FROM my_models INNER JOIN bs ON bs.id = my_models.b_id INNER JOIN as ON a.id = my_models.a_id

But with Sequel:

MyModel.join(:as, id: :a_id).join(:bs, id: :b_id)

gives the following SQL:

SELECT * FROM my_models INNER JOIN bs ON bs.id = my_models.b_id INNER JOIN as ON a.id = bs.a_id

Why does join use the last joined table's name? How do I get the same SQL generated by ActiveRecord in Sequel?

Answer 1

By default in Sequel's join, the implicit qualifier is the last joined table.

So,

MyModel.join(:as, id: :a_id).join(:bs, id: :b_id)

equals:

MyModel.join(:as, id: :a_id).join(:bs, id: Sequel[:as][:b_id])

Use an explicit qualifier:

MyModel.join(:as, id: :a_id).join(:bs, id: Sequel[:my_models][:b_id])

This is from the official Sequel IRC chat with @jeremyevans.