Merge with joins adds secondary joins to wrong part of query

[quickdudley]

Steps to reproduce

I have a query along these lines:

joins("RIGHT JOIN (p LEFT JOIN s ON s.p_id = p.id) ON s.a_id = a.id OR p.a_id = a.id").merge(p_scope)

If p_scope contains no joins: the query works as expected. If p_scope contains joins: the full query is constructed incorrectly.

Expected behavior

In the event that p_scope contains joins: the generated SQL should be along the line of:

RIGHT JOIN (p LEFT JOIN s ON s.p_id = p.id) ON s.a_id = a.id OR p.a_id = a.id <join clauses from p_scope>

Actual behavior

The generated SQL is along the lines of:

<join clauses from p_scope> RIGHT JOIN (p LEFT JOIN s ON s.p_id = p.id) ON s.a_id = a.id OR p.a_id = a.id

This is a problem because SQL join syntax is left-associative: the join clauses from p_scope refer to columns which are outside of their namespace.

System configuration

Rails version:
Rails 5.0.0.1
Ruby version:
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin17]

[y-yagi]

Can you create an executable test script using one of the templates here, that would demonstrate the problem you are seeing?

[kamipo]

This is a same issue with #12953 and #24281.
A string joins doesn't work with symbol joins for now.

[quickdudley]

I've also been seeing the same issue with symbol joins. During the weekend I will make a test script.

[quickdudley]

Replicating the problem with symbol joins in a test script proved more difficult than expected. I currently have a scope which works as intended in rails console and in a test script but fails when called with the same arguments from a controller.

[rails-bot]

This issue has been automatically marked as stale because it has not been commented on for at least three months.
The resources of the Rails team are limited, and so we are asking for your help.
If you can still reproduce this error on the 5-2-stable branch or on master, please reply with all of the information you have about it in order to keep the issue open.
Thank you for all your contributions.

[tibbon]

Thanks for working on this @quickdudley!

[chumakoff]

For those who has the same problem there is a workaround:

Instead of

BaseModel.joins("<base_scope_join_clauses>").merge(second_scope)

do this:

base_scope = BaseModel.joins("<base_scope_join_clauses>")
BaseModel.joins(base_scope.join_sources).joins(second_scope.join_sources)