CODEWITHSUNDEEP
ruby-on-railsrubyransack
Richi Zee
Richi Zee

Reputation: 374

Why Ransack performs a query in each loop

I search with all members for a special group:

Controller:

class Groups::MembersController < ApplicationController

  def index
    @group = Group.find_by_name(params[:groupname])
    @search = @group.members.ransack(params[:q])
    @members = @search.result().includes(:user).page(params[:page]).per(5)
    respond_to do |format|
      format.js
      format.html
    end
  end
  ...

Model:

class Member < ApplicationRecord
  belongs_to :user
  belongs_to :group
end

View: Here puts were deposited.

...
- puts 'Out'
- @members.each do |member|
  - puts 'In'
  - user = member.user
  - userShow = user_path(user)
  .list-group-item{id: member.id}
  ...

Output:

Started GET "/groups/Test/members" for 127.0.0.1 at
Processing by Groups::MembersController#index as HTML
  Parameters: {"groupname"=>"Test"}
  Group Load (0.0ms)  SELECT  "groups".* FROM "groups" WHERE "groups"."name" = ? LIMIT ?  [["name", "Test"], ["LIMIT", 1]]
  Rendering groups/members/index.html.haml within layouts/application
  Rendered layouts/nav/sidebar/_groups.html.haml (4.0ms)
Out
  Member Load (0.0ms)  SELECT  "members".* FROM "members" WHERE "members"."group_id" = ? LIMIT ? OFFSET ?  [["group_id", 2], ["LIMIT", 5], ["OFFSET", 0]]
  User Load (0.5ms)  SELECT "users".* FROM "users" WHERE "users"."id" IN (15, 24, 48, 9, 4)
In
  Member Load (0.0ms)  SELECT  "members".* FROM "members" WHERE "members"."group_id" = ? LIMIT ?  [["group_id", 2], ["LIMIT", 11]]
In
  CACHE Member Load (0.0ms)  SELECT  "members".* FROM "members" WHERE "members"."group_id" = ? LIMIT ?  [["group_id", 2], ["LIMIT", 11]]
In
  CACHE Member Load (0.0ms)  SELECT  "members".* FROM "members" WHERE "members"."group_id" = ? LIMIT ?  [["group_id", 2], ["LIMIT", 11]]
In
  CACHE Member Load (0.0ms)  SELECT  "members".* FROM "members" WHERE "members"."group_id" = ? LIMIT ?  [["group_id", 2], ["LIMIT", 11]]
In
  CACHE Member Load (0.0ms)  SELECT  "members".* FROM "members" WHERE "members"."group_id" = ? LIMIT ?  [["group_id", 2], ["LIMIT", 11]]
  Rendered groups/members/_index_list.html.haml (7068.8ms)
   (0.0ms)  SELECT COUNT(*) FROM "members" WHERE "members"."group_id" = ?  [["group_id", 2]]
  Rendered groups/members/index.html.haml within layouts/application (7313.5ms)
  Rendered layouts/_head.html.haml (274.7ms)
  User Load (0.5ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? ORDER BY "users"."id" ASC LIMIT ?  [["id", 1], ["LIMIT", 1]]
  Rendered layouts/header/_default.html.haml (7.0ms)
  Rendered layouts/_nav.html.haml (2.0ms)
  Rendered layouts/_flash.html.haml (14.0ms)
Completed 200 OK in 7965ms (Views: 7931.9ms | ActiveRecord: 1.0ms)

I do not understand why a query is executed here in each loop. Even if done with CACHE, it costs me performance. Can I fix it?

Upvotes: 4

Views: 415

Answers (1)

lacostenycoder
lacostenycoder

Reputation: 11226

I think you're mistaken about where the delay is. Instrument your code with some timestamps and post what happens:

- puts "before loop: #{Time.now.to_s(:utc)}"
- puts 'Out'
- @members.each do |member|
  - puts "In loop  #{Time.now.to_s(:utc)}"
  - user = member.user
    - puts "after member.user call  #{Time.now.to_s(:utc)}"
  - userShow = user_path(user)
  .list-group-item{id: member.id}
- puts "End loop  #{Time.now.to_s(:utc)}"

Upvotes: 1

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