`with_annotation` doesn't work on relations

[Jacob Bednarz]

While starting to use with_annotation in some of our queries, I am finding that it doesn't work on where methods (and I suspect other AR relation methods).

Rails version: 5.2
Gem version: 1.8.0

# works
Marginalia.with_annotation("foo") { User.first }
#=> SELECT * FROM `users` LIMIT 1 /*foo*/

# works
Marginalia.with_annotation("foo") { User.find_by_id(1) }
#=> SELECT * FROM `users` WHERE `id` = 1 LIMIT 1 /*foo*/

# doesn't
Marginalia.with_annotation("foo") { User.where(id: 1) }
#=> SELECT * FROM `users` WHERE `id` = 1 LIMIT 11

Is this a known thing or any hints as to how to address it?

[Steve Hodgkiss]

The reason the last one doesn't appear to work as expected is because the query is actually evaluated when it's returned to pry/irb, not when it's inside the with_annotation block. Adding .to_a to the relation inside the block should make the comment appear.

[Samuel Cochran]

Yeah sorry this is not a bug.

This will do what you expect for the reasons @stevehodgkiss mentions:

Marginalia.with_annotation("foo") { User.where(id: 1).to_a }

If you're using rails 6+ and you want an annotation to follow your relation then you might like to use #annotate on your relation:

User.where(id: 1).annotate("foo")