Mongoid拋出16052例外

Question

我想用mongoid來實現查詢funcation喜歡 'GROUP BY'，但我捕獲的異常：

failed with error 16052: "exception: could not create cursor over th_test.messages for query : { sr_flag: /.*541260c5aee1a93f70000001.*/ } sort : { created_at: -1 }" 

我的代碼是在這裏：

def messages 
    map = %Q{ 
     function() { 
     emit(this.sr_flag, { count: 1 }); 
     } 
    } 

    reduce = %Q{ 
     function(key, values) { 
     var result = { count: 0 }; 
     values.forEach(function(value) { 
      result.count += value.count; 
     }); 
     return result; 
     } 
    } 

    result = Message.where(sr_flag: /.*#{self.id}.*/).map_reduce(map, reduce).out(inline: true).to_a 
    result 
end 

能

人幫我解釋一下爲什麼？我搜索了blog。mongoid是否將created_at列設置爲主鍵？

Answer 1

我已經解決了我的問題。原因是有人爲我的消息模型編寫了default_scope，但是the column sorted on was not the key column of the map method。只是使用unscoped方法使程序工作。

result = Message.unscoped.where(sr_flag: /.*#{self.id}.*/).map_reduce(map, reduce).out(inline: true).to_a