Question

我有以下设置：

question.rb

class Question < ActiveRecord::Base
    has_many :answers

    #validations, methods, etc
    ...

    #Returns the questions with the most answers
    def Question.top_questions(max = 10)
        sql = "SELECT question_id, COUNT('question_id') as aCount FROM answers GROUP BY question_id ORDER BY aCount DESC LIMIT #{max.to_i}" # Probably shouldn't use string interpolation here :D
        Question.connection.execute(sql)
    end
end

answer.rb

class Answer < ActiveRecord::Base
    belongs_to :question
    ...
end

如果我调用Question.top_questions（），那么它会返回：

[{＆＃34; question_id＆＃34; =＆gt; 1，＆＃34; aCount＆＃34; =＆gt; 25,0 =＆gt; 1,1 =＆gt; 25}，{＆＃34; question_id＆＃34; =＆gt; 38，＆＃34; aCount＆＃34; =＆gt; 3,0 =＆gt; 38,1 =＆gt; 3}，{＆＃34; question_id＆＃34; =＆gt; 45，＆＃ 34; aCount＆＃34; =＆gt; 3,0 =＆gt; 45,1 =＆gt; 3}，{＆＃34; question_id＆＃34; =＆gt; 26，＆＃34; aCount＆＃34; =＆gt; 2 ，0 =＆gt; 26,1 =＆gt; 2}，{＆＃34; question_id＆＃34; =＆gt; 46，＆＃34; aCount＆＃34; =＆gt; 2,0 =＆gt; 46,1 =＆gt; ; 2}，{＆＃34; question_id＆＃34; =＆gt; 48，＆＃34; aCount＆＃34; =＆gt; 2,0 =＆gt; 48,1 =＆gt; 2}，{＆＃34; question_id＆＃34; =＆gt; 51，＆＃34; aCount＆＃34; =＆gt; 2,0 =＆gt; 51,1 =＆gt; 2}，{＆＃34; question_id＆＃34; =＆gt; 5，＆＃ 34; aCount＆＃34; =＆gt; 1,0 =＆gt; 5,1 =＆gt; 1}，{＆＃34; question_id＆＃34; =＆gt; 15，＆＃34; aCount＆＃34; =＆gt; 1 ，0 =＆gt; 15,1 =＆gt; 1}，{＆＃34; question_id＆＃34; =＆gt; 20，＆＃34; aCount＆＃34; =＆gt; 1,0 =＆gt; 20,1 =＆gt; ; 1}]

我不确定在保持代码清洁的同时如何使用视图中返回的数据。所以我想知道我是否可以使用rails＆＃39;来编写Question.top_questions()方法。读取方法（find（），where（）等）。或者我如何让它返回一个Question对象数组。

Answer 1

它返回一个哈希数组，您可以根据需要在视图中使用它。

但如果您不想编写本机sql，可以按如下所示重写它。

def self.top_questions(max = 10)
    Question.joins('LEFT JOIN answers ON questions.id = answers.question_id')
            .select('questions.*, count(answers.id) as answers_count')
            .group('questions.id')
            .order('answers_count desc')
            .limit(max)        
end

如何使用Rails的读取方法编写此SQL？

1 个答案: