Question

我有一个句子和修正模型

class Sentence < ActiveRecord::Base
    has_one :correction

class Correction < ActiveRecord::Base
   belongs_to :sentence

我正在尝试查找所有没有更正的句子。为此，我只是寻找不存在的校正，即其id = nil。但它失败了，我无法弄清楚为什么

 Sentence.find :all, :include => :correction, :conditions => {:correction => {:id => nil}}

from (irb):4>> Sentence.find :all, :include => :correction, :conditions => {:correction => {:id => nil}}

ActiveRecord :: StatementInvalid：Mysql :: Error：'where子句'中的未知列'correction.sentence_id'：SELECT * FROM sentences WHERE（correction。sentence_id IS NULL）

也许是语法或者只是整体方法。有人可以帮忙吗？

Answer 1

您可以使用：

Sentence.all(:include => :correction, 
  :conditions => "corrections.sentence_id IS NULL")

Rails - using：include根据子项的属性查找对象

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