Ruby on Rails的：尋找在返回的搜索查詢

Question

我試圖找到一個名爲length列，這是簡單的整數列充滿秒每條記錄歷時數的總和列的總和。

我有一個搜索表單設置要查詢的一些情況我已經在控制器中設置的DB：

@time_entries = TimeEntry.find(:all, :conditions => [ "(user_id = ?) AND (projecttitle LIKE ?) AND (date BETWEEN ? AND ?)", current_user, '%'+params[:projecttitle]+'%', @startdate, @enddate ]) 

，然後我跟着我的代碼不起作用該查詢，試圖求和我返回的查詢的length列...

@total_time = @time_entries.sum(:length) 

，然後當我走在我的<%= @total_time %>視圖渲染了這一點，我得到這個錯誤：

undefined method '+' for #<TimeEntry:0x007ffdbbd45b78>

任何想法？你的幫助是非常appretiated :)

Answer 1

變化

@total_time = @time_entries.sum(:length) 

到

@total_time = @time_entries.sum(&:length) 

僅供參考，如果你只需要一列像

@time_entries = TimeEntry.find(:all, :select => 'length', 
        :conditions => [ "(user_id = ?) AND (projecttitle LIKE ?) 
          AND (date BETWEEN ? AND ?)", current_user, 
          '%'+params[:projecttitle]+'%', @startdate, @enddate ]) 

操作使用 :select子句中查詢

如果你只需要表中某列的總和，你可以使用sum方法如

@total_time = TimeEntry.sum(:length, 
        :conditions => [ "(user_id = ?) AND (projecttitle LIKE ?) 
          AND (date BETWEEN ? AND ?)", current_user, 
          '%'+params[:projecttitle]+'%', @startdate, @enddate ])