Stream results from the database into Ruby objects

stream_each.rb

require 'ostruct'

Post = Comment = User = OpenStruct

class PostsWithComments
  def call
    results = Model.connection.execute <<~SQL
      SELECT
        posts.id,
        posts.title,
        posts.published_at,
        comments.id,
        comments.body,
        comments.created_at,
        users.id,
        users.name
      FROM posts
      LEFT JOIN comments ON comments.post_id = posts.id
      LEFT JOIN users ON comments.author_id = users.id
      WHERE posts.published_at < now()
      ORDER BY posts.published_at DESC, comments.created_at DESC
    SQL

    results.each do |row|
      post = Post.new(
        id: row[0],
        title: row[1],
        published_at: Time.parse(row[2]),
      )
      comment = Comment.new(
        id: row[3],
        title: row[4],
        created_at: Time.parse(row[5]),
      )
      author = User.new(
        id: row[6],
        name: row[7],
      )

      yield post, comment, author
    end
  end
end

PostsWithComments.new.call do |post, comment, author|
  # ...
end