Arel/AR not replacing binds correct?

[arthurnn]

Using this script:
https://gist.github.com/arthurnn/8702117

mysql output:

"SELECT `posts`.`title` FROM `posts`  WHERE `posts`.`author_id` = 1"

postgres output:

"SELECT \"posts\".\"title\" FROM \"posts\"  WHERE \"posts\".\"author_id\" = $1"

sqlite3 output:

"SELECT \"posts\".\"title\" FROM \"posts\"  WHERE \"posts\".\"author_id\" = ?"

Is this correct? (AFAIK, the ? and $1 should had been replaced)
author.posts.select(:title) returns a Relation, which calls to_sql https://github.com/rails/rails/blob/master/activerecord/lib/active_record/relation.rb#L510 . So that means that the binds are in place, so that might be an issue on AREL? (if it is a AREL thing, I can open a issue in there)

maybe related #12753 ?

thoughts @tenderlove @rafaelfranca @carlosantoniodasilva

[rafaelfranca]

This is correct. Who finally replace the binds are the database adapter when doing the query.

[arthurnn]

good point =)

[arthurnn]

So, select_row should receive the binds, in case we have these queries. see https://github.com/rails/rails/blob/master/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb#L48

[rafaelfranca]

See adequaterecord branch for adequate reason. If we replace the binds before the database connection call we would not have how to cache the prepared statements.

That branch also explain why the to_sql implementation of Relation can't use the database adapter version

[arthurnn]

Got it... everything is clear now...
So select_row should receive the query(without replacing the binds), and the bind array?

[rafaelfranca]

Yes, it should.

[arthurnn]

✨
will do that on #13886 ... And remote the to_sql refactoring.