如何按喜欢计数对用户的答案进行排序？

Question

I wanna iterate over all user's answers and order it by amount of likes which an answer has received, but I can't figure out how to do it, @user.answers.likes doesn't work, I found a way to find all user's answers which have likes, but that's not exactly what I want to do. Thank you for your help.

models/answer.rb

class Answer < ApplicationRecord
belongs_to :question
belongs_to :user
has_many :likes, dependent: :destroy

models/user.rb

class User < ApplicationRecord
has_many :answers
has_many :likes

models/like.rb

class Like < ApplicationRecord
belongs_to :user
belongs_to :answer

schema.rb

create_table "answers", force: :cascade do |t|
 t.text     "content"
 t.datetime "created_at",                  null: false
 t.datetime "updated_at",                  null: false
 t.integer  "question_id"
 t.integer  "user_id"
 t.boolean  "accepted",    default: false
 t.index ["question_id"], name: "index_answers_on_question_id"
end

create_table "likes", force: :cascade do |t|
 t.integer  "user_id"
 t.integer  "answer_id"
 t.datetime "created_at", null: false
 t.datetime "updated_at", null: false
end

Answer 1

Something like this should work in pure SQL.

sql = "SELECT * FROM answers INNER JOIN likes ON answers.id = likes.answer_id WHERE COUNT(likes.id) > 0 AND answers.user_id = #{@user.id}  GROUP BY answers.id ORDER BY COUNT(likes.id)"

records_array = ActiveRecord::Base.connection.execute(sql)

Answer 2

@user.answers.joins(:likes)
    .select('answers.*, COUNT(likes.id) as likes_count')
    .group('answers.id')
    .order('likes_count DESC')

If you want to select only answers with likes you can add having condition

@user.answers.joins(:likes)
    .select('answers.*, COUNT(likes.id) as likes_count')
    .group('answers.id')
    .having('COUNT(likes.id) > 0')
    .order('likes_count DESC')