'How to call pluck with multiple table without using string params

If I have the following code:

User.where(users: {id: [1,2,3,4,5] } )
  .joins("left outer join carts on users.id = carts.user_id)
  .pluck("user.id", "user.name", "carts.id")

And this work fine. But I think it is cleaner if I can do something similar to the where clause like:

User.where(users: {id: [1,2,3,4,5] } )
  .joins("left outer join carts on users.id = carts.user_id)
  .pluck(users: [:id, :name], carts : [:id])

Is the second approach possible?

Also to note I know the left_joins method exists but I'm not using it here to make the example clear.

ruby-on-rails


Solution 1:[1]

Second approach is not possible, look at the source:

 # File activerecord/lib/active_record/relation/calculations.rb, line 183
    def pluck(*column_names)
      if loaded? && all_attributes?(column_names)
        return records.pluck(*column_names)
      end

      if has_include?(column_names.first)
        relation = apply_join_dependency
        relation.pluck(*column_names)
      else
        klass.disallow_raw_sql!(column_names)
        columns = arel_columns(column_names)
        relation = spawn
        relation.select_values = columns
        result = skip_query_cache_if_necessary do
          if where_clause.contradiction?
            ActiveRecord::Result.new([], [])
          else
            klass.connection.select_all(relation.arel, nil)
          end
        end
        type_cast_pluck_values(result, columns)
      end
    end

https://apidock.com/rails/ActiveRecord/Calculations/pluck

Solution 2:[2]

That hash syntax won't work - but if you want to avoid using strings you can use Arel to avoid hardcoding the table names:

users, carts = User.arel_table, Cart.arel_table

User.where(id: [1,2,3,4,5]) # you don't need to be specific if its on "this" models table
  .joins("left outer join carts on users.id = carts.user_id")
  .pluck(users[:id], users[:name], carts[:id])

Sources

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Source: Stack Overflow

Solution Source
Solution 1 stolarz
Solution 2 max

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