链接命名范围并不如预期 [英] Chaining Named Scopes not working as intended

问题描述

我有2个简单的命名范围定义为这样的：

I have 2 simple named scopes defined as such:

class Numbers < ActiveRecord::Base
  named_scope :even, :conditions => {:title => ['2','4','6']}
  named_scope :odd, :conditions => {:title => ['1','3','5']}
end

如果我打电话Numbers.even我回来2,4,6这是正确的 如果我叫Numbers.odd我回来1,3,5这是正确的。

if I call Numbers.even I get back 2,4,6 which is correct if I call Numbers.odd I get back 1,3,5 which is correct

当我把它们连在一起就像这样：Numbers.even.odd我回去1,3,5，因为这是最后的范围，我引用。所以，如果我说Numbers.odd.even我反而得到2,4,6。

When I chain them together like this: Numbers.even.odd I get back 1,3,5 because that is the last scope I reference. So if I say Numbers.odd.even I would actually get 2,4,6.

我希望得到1,2,3,4,5,6，当我把它们结合在一起。我想另外一个办法是这样的：

I would expect to get 1,2,3,4,5,6 when I chain them together. One other approach I tried was this:

named_scope :even, :conditions => ["title IN (?)", ['2', '4','6']]
named_scope :odd, :conditions => ["title IN (?)", ['1', '3','5']]

不过，我没有得到任何结果时，我把它们结合在一起，因为它创建查询看起来是这样的：

But I get no results when I chain them together because the query it creates looks like this:

SELECT * FROM `numbers` 
WHERE ((title IN ('1','3','5')) AND (title IN ('2','4',6')))

在'与'条款应改为OR，但我不知道如何给力的。难道这是一个问题的ActiveRecord？

The 'AND' clause should be changed to OR but I have no idea how to force that. Could this be an issue with ActiveRecord??

推荐答案

这是一个问题的ActiveRecord如何处理范围。当您应用多个领域，结果与AND连接在一起。有使用或不选。

It's an issue with how ActiveRecord handles scopes. When you apply multiple scopes, the results are joined together with AND. There is no option for using OR.

您需要做的，而不是什么是合并两个结果集：

What you need to do instead is combine two result sets:

Numbers.even.all + Numbers.odd.all

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