ActiveRecord JSON examples

active_record_to_json.rb

User.limit(2).as_json
#  User Load (2.0ms)  SELECT  "users".* FROM "users" LIMIT ?  [["LIMIT", 2]]
#=> [{"id"=>1, "name"=>"Анна Терентьева", "created_at"=>Wed, 23 Jan 2019 21:47:37 UTC +00:00, "updated_at"=>Wed, 23 Jan 2019 21:47:37 UTC +00:00, "photo_url"=>nil, "nickname"=>nil, "first_name"=>nil, "last_name"=>nil, "about"=>nil, "birthday"=>nil}, {"id"=>2, "name"=>"Абрамова София", "created_at"=>Wed, 23 Jan 2019 21:47:38 UTC +00:00, "updated_at"=>Wed, 23 Jan 2019 21:47:38 UTC +00:00, "photo_url"=>nil, "nickname"=>nil, "first_name"=>nil, "last_name"=>nil, "about"=>nil, "birthday"=>nil}]

User.select(:id, :name).limit(2).as_json
#  User Load (1.4ms)  SELECT  "users"."id", "users"."name" FROM "users" LIMIT ?  [["LIMIT", 2]]
#=> [{"id"=>2, "name"=>"Абрамова София"}, {"id"=>20, "name"=>"Ангелина Нестерова"}]


User.select(:id, :name).where('start_at > ?', Time.now).limit(2).as_json
#  User Load (1.6ms)  SELECT  "users"."id", "users"."name" FROM "users" WHERE (start_at > '2019-01-25 06:50:27.895229') LIMIT ?  [["LIMIT", 2]]
#ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: start_at: SELECT  "users"."id", "users"."name" FROM "users" WHERE (start_at > '2019-01-25 06:50:27.895229') LIMIT ?
#        from (irb):10

User.select(:id, :name).joins(:events).where('start_at > ?', Time.now).limit(2).as_json
#  User Load (1.9ms)  SELECT  "users"."id", "users"."name" FROM "users" INNER JOIN "events" ON "events"."user_id" = "users"."id" WHERE (start_at > '2019-01-25 06:51:12.674080') LIMIT ?  [["LIMIT", 2]]
#=> [{"id"=>1, "name"=>"Анна Терентьева"}, {"id"=>1, "name"=>"Анна Терентьева"}]

User.select(:id, :name).limit(2).map { |u| { user_id: u.id, time: Time.now, foo: [:bar] } }.as_json
#  User Load (0.7ms)  SELECT  "users"."id", "users"."name" FROM "users" LIMIT ?  [["LIMIT", 2]]
#=> [{"user_id"=>2, "time"=>"2019-01-25T06:55:16.845+00:00", "foo"=>["bar"]}, {"user_id"=>20, "time"=>"2019-01-25T06:55:16.845+00:00", "foo"=>["bar"]}]

User.select(:id, :name).joins(:events).limit(2).map { |u| { user: u, events: u.events.select(:title, :start_dt).limit(2) } }.as_json
#  User Load (1.7ms)  SELECT  "users"."id", "users"."name" FROM "users" INNER JOIN "events" ON "events"."user_id" = "users"."id" LIMIT ?  [["LIMIT", 2]]
#  Event Load (1.5ms)  SELECT  "events"."title", "start_dt" FROM "events" WHERE "events"."user_id" = ? LIMIT ?  [["user_id", 1], ["LIMIT", 2]]
#  Event Load (1.0ms)  SELECT  "events"."title", "start_dt" FROM "events" WHERE "events"."user_id" = ? LIMIT ?  [["user_id", 1], ["LIMIT", 2]]
#=> [{"user"=>{"id"=>1, "name"=>"Анна Терентьева"}, "events"=>[{"id"=>nil, "title"=>"Accusamus in sunt quos.", "\"start_dt\""=>"start_dt"}, {"id"=>nil, "title"=>"Corporis excepturi quisquam ea.", "\"start_dt\""=>"start_dt"}]}, {"user"=>{"id"=>1, "name"=>"Анна Терентьева"}, "events"=>[{"id"=>nil, "title"=>"Accusamus in sunt quos.", "\"start_dt\""=>"start_dt"}, {"id"=>nil, "title"=>"Corporis excepturi quisquam ea.", "\"start_dt\""=>"start_dt"}]}]