AR 5.2.1 and 5.2.2 transitive polymorphic association results in INNER JOIN which breaks "or" searches

[dholdren]

Problem

When searching a model's polymorphic association's association's field in Rails 5.2 ransack generates a INNER JOIN which causes or type searches to break
(i.e. a Note's notable Article's comment's body)

Working combination: Rails 5.0, ransack 2.1.1 (latest):

This generates LEFT OUTER JOINs for everything

➜  ransack git:(master) rake console
[1] pry(main)> puts Note.ransack("notable_of_Article_type_comments_body_cont" => "First").result.to_sql
SELECT "notes".* FROM "notes" 
LEFT OUTER JOIN "articles" ON "articles"."id" = "notes"."notable_id" AND "notes"."notable_type" = 'Article' AND ('default_scope' = 'default_scope') 
LEFT OUTER JOIN "comments" ON "comments"."article_id" = "articles"."id" 
WHERE ("comments"."body" LIKE '%First%')
=> nil

[2] pry(main)> puts Note.ransack("notable_of_Person_type_name_or_notable_of_Article_type_comments_body_cont" => "First").result.to_sql
SELECT "notes".* FROM "notes" 
LEFT OUTER JOIN "people" ON "people"."id" = "notes"."notable_id" AND "notes"."notable_type" = 'Person' 
LEFT OUTER JOIN "articles" ON "articles"."id" = "notes"."notable_id" AND "notes"."notable_type" = 'Article' AND ('default_scope' = 'default_scope') 
LEFT OUTER JOIN "comments" ON "comments"."article_id" = "articles"."id" 
WHERE ("people"."name" LIKE '%First%' OR "comments"."body" LIKE '%First%')
=> nil

Broken combination Rails 5.2.2 (also 5.2.1), ransack 2.1.1 (latest)

This generates an INNER JOIN for the comments table so it ignores any other tables we chose to search

ransack git:(master) RAILS=v5.2.2 rake console
[1] pry(main)> puts Note.ransack("notable_of_Article_type_comments_body_cont" => "First").result.to_sql
SELECT "notes".* FROM "notes" 
LEFT OUTER JOIN "articles" ON "articles"."id" = "notes"."notable_id" AND ('default_scope' = 'default_scope') 
INNER JOIN "comments" ON "comments"."article_id" = "articles"."id" 
WHERE "comments"."body" LIKE '%First%'
=> nil

[2] pry(main)> puts Note.ransack("notable_of_Person_type_name_or_notable_of_Article_type_comments_body_cont" => "First").result.to_sql
SELECT "notes".* FROM "notes" 
LEFT OUTER JOIN "people" ON "people"."id" = "notes"."notable_id" 
LEFT OUTER JOIN "articles" ON "articles"."id" = "notes"."notable_id" AND ('default_scope' = 'default_scope') 
INNER JOIN "comments" ON "comments"."article_id" = "articles"."id" 
WHERE ("people"."name" LIKE '%First%' OR "comments"."body" LIKE '%First%')
=> nil

Additional bug

You can see in the Rails 5.2.2 example, that the polymorphic associations LEFT OUTER JOIN aren't limited by notable_type. This causes other issues. This was reported in #902

[dholdren]

@gregmolnar Is anyone actively looking into this or #955 ? (sorry for the dup)

Also the separate, but related #902

These are show-stopper bugs for Rails 5.2.1+, polymorphic relationship searches are broken

[gregmolnar]

@dholdren I am struggling with time recently and as far as I know others are not looking into this either. If all goes well, I should be able to look into it this weekend/early next week.

[gregmolnar]

@dholdren Can you verify that this PR fixes your issue? #1004

[dholdren]

@dholdren Can you verify that this PR fixes your issue? #1004

@gregmolnar Yes it looks good. LEFT OUTER joins, and they now have the polymorphic constraint. thanks!