Unsafe autocorrect with Rails/Pluck

[axlekb]

If column name is aliased in a select clause, using .pluck('alias_column') in place of .map { |post| post['alias_column'] } will cause an ActiveRecord::StatementInvalid

Cop docs:

# bad
Post.published.map { |post| post[:title] }
[{ a: :b, c: :d }].collect { |el| el[:a] }

# good
Post.published.pluck(:title)
[{ a: :b, c: :d }].pluck(:a)

---

Expected behavior

Autocorrect should not result in changes that raise an error

Actual behavior

Autocorrect causes ActiveRecord::StatementInvalid

Steps to reproduce the problem

• Add a #join and #select clause to an ActiveRecord::Relation. (e.g. .select("table_1.*", "table_2.id AS table_2_id"))

Using .map { |x| x['table_2_id'] } returns an Array of the aliased column
Using .pluck('table_2_id') raises an ActiveRecord::StatementInvalid because table_2_id is not a table column
Using .to_a.pluck('table_2_id') returns an Array of the aliased column

RuboCop version

$ rubocop -V
1.37.0 (using Parser 3.1.2.1, rubocop-ast 1.23.0, running on ruby 3.0.4) [arm64-darwin21]
  - rubocop-performance 1.15.0
  - rubocop-rails 2.17.0
  - rubocop-rspec 2.13.2

[jcoyne]

See further examples in #842 where the target is not an AR::Relation, but a simple ruby Hash.

[vlad-pisanov]

+1 unfortunately, the cop is inherently unsafe when column aliasing is used:

User.select('id AS id2').map { |user| user[:id2] } # works ✔️
User.select('id AS id2').pluck(:id2)               # ERROR:  column "id2" does not exist ❌
User.select('id AS id2').to_a.pluck(:id2)          # works ✔️

[Drenmi]

I suspect the most we can do is mark this auto-correct as unsafe.