Querying against a non-default primary key uses wrong value

[x2764tech]

I have a gist: https://gist.github.com/x2764tech/4ff7c015cd5d7137c295

I have the follow models:

class Post < ActiveRecord::Base
  has_many :comments, primary_key: :system_id
end

class Comment < ActiveRecord::Base
  belongs_to :post, primary_key: :system_id
end

and the test

class BugTest < Minitest::Test
  def test_association_stuff
    post = Post.create! system_id: 23
    post.comments << Comment.create!

    assert Comment.exists?(post: post)
  end
end

The data is created successfully, but the query to check whether a post exists uses Post.id and not Post.system_id:

SELECT  1 AS one FROM "comments" WHERE "comments"."post_id" = 1 LIMIT 1

The query should use the primary key specified in the relationship.

[x2764tech]

I don't know if it helps, but I noticed this in 4.1.6, and replicated it in 4.1.9 and 4.2.0, as well as the master branch

[sgrif]

This looks like the correct behavior. You are confusing the primary_key and foreign_key options.

[sgrif]

Never mind, I misread your issue.

[sgrif]

This is my daily reminder not to go through the issue tracker before I've had my coffee...

[x2764tech]

@sgrif In production code, it uses a named foreign_key as well, so I was pretty certain I had it right.

[sgrif]

Yes, you have it right. I was just reading it wrong. I'm drinking my coffee now, and then I'll fix it. 😁

[sgrif]

This might not be something that can be backported to pre-5.0, since the fix on master depends a lot on the refactoring work I've been doing this year. I'll see what I can do to get it on 4.2 and 4.1 though

[x2764tech]

In case I hit this again:

The obvious work-around is to query the foreign-key column with the correct primary-key value instead of the object, e.g. in the example above

Comment.exists?(post_id: post.system_id)

returns the correct result.

[sgrif]

You can also just pass the ID without changing the column. Doing Comment.exists?(post: post.system_id) will work, as well. However, I got the backport working for 4.2 and 4.1, I'll link the commits here when I'm done.

[sgrif]

Backported for 4.1.10 in b8ba202

Backported for 4.2.1 in e43d96c

Thank you for the report.

[x2764tech]

@sgrif Thanks for the quick fix!

[sgrif]

Any time. It's my job. :)