rails中控制器的不同操作中的相同代码-如何使DRY？

Question

我有一个具有两个不同操作的控制器，但都需要相同的代码，这有点长，我怎样才能让他们访问相同的行为但保持干燥？

   @list = Contact.find :all,
      :select => "companies.name AS co_name, 
                  companies.id AS comp_id, 
                  COUNT(contact_emails.id) AS email_count, 
                  COUNT(contact_calls.id) AS call_count, 
                  COUNT(contact_letters.id) AS letter_count, 
                  COUNT(contact_postalcards.id) AS postalcard_count",

      :conditions => ['contact_emails.date_sent < ? and contact_emails.date_sent > ?', 
                      report_end_date, report_start_date],

      :joins => [
        "LEFT JOIN companies ON companies.id = contacts.company_id",
        "LEFT JOIN contact_emails ON contact_emails.contact_id = contacts.id",
        "LEFT JOIN contact_letters ON contact_letters.contact_id = contacts.id",
        "LEFT JOIN contact_postalcards ON contact_postalcards.contact_id = contacts.id",
        "LEFT JOIN contact_calls ON contact_calls.contact_id = contacts.id"
      ],
      #:group => "companies.id"
       :group => "companies.name"
    puts @list[0].attributes.inspect

Answer 1

您应该将此代码移至模型：

# Contatct model

def self.get_list(report_start_date, report_end_date)
  self.find :all,
    :select => "companies.name AS co_name, 
              companies.id AS comp_id, 
              COUNT(contact_emails.id) AS email_count, 
              COUNT(contact_calls.id) AS call_count, 
              COUNT(contact_letters.id) AS letter_count, 
              COUNT(contact_postalcards.id) AS postalcard_count",

    :conditions => ['contact_emails.date_sent < ? and contact_emails.date_sent > ?', 
                  report_end_date, report_start_date],

    :joins => [
      "LEFT JOIN companies ON companies.id = contacts.company_id",
      "LEFT JOIN contact_emails ON contact_emails.contact_id = contacts.id",
      "LEFT JOIN contact_letters ON contact_letters.contact_id = contacts.id",
      "LEFT JOIN contact_postalcards ON contact_postalcards.contact_id = contacts.id",
      "LEFT JOIN contact_calls ON contact_calls.contact_id = contacts.id"
    ],
    #:group => "companies.id"
    :group => "companies.name"
end

然后你可以在控制器中使用它：

@list = Contact.get_list(report_start_date, report_end_date)

也许您也可以将其拆分为更小的部分并使用范围和定义的关联，而不是自己编写所有内容。

Answer 2

我会添加一个函数来生成计数并加入 sql：

class Contact < ActiveRecord::Base
  def  self.get_list(report_start_date,    report_end_date)
    all(:select      => "companies.name AS co_name,
                        companies.id AS comp_id,
                        #{table_count_col(
                          :contact_emails, 
                          :contact_calls, 
                          :contact_letters, 
                          :contact_postalcards
                         )}",
        :conditions => ['contact_emails.date_sent < ?  AND
                         contact_emails.date_sent > ?',
                         report_end_date, report_start_date],
        :joins      => join_table(
                    :companies, 
                    :contact_emails, 
                    :contact_letters, 
                    :contact_postalcards, 
                    :contact_calls
                    ),
       )
  end
end

其中table_count_col 和table_join 是Contact 类中的静态方法：

  def self.table_count_col(*args)    
    args.collect do |table| 
      count_col = "#{table.to_s.gsub(/^contact_/,  '').singularize}_count"
      "COUNT(#{table}.id) AS #{count_col}"    
    end.join(",")
  end

  def self.table_join(*args)    
    args.collect do |table|
     "LEFT JOIN #{table} ON #{table}.id = contacts.company_id"
    end.join(",")
  end