NoMethodError：未定义的方法`created_at'属性的Rails中 [英] NoMethodError: undefined method `created_at' for in Rails

问题描述

因此​​，这里是我的ActiveRecord的检索的对象其它= [＃＆LT;推荐人ID：16，店名：其他，发表：真的，created_at：2011-07-11 16： 22:00的updated_at：2011-07-11 16时22分00秒＆GT;] 我为什么不能做 other.created_at ，而我能做的 other.name ？

So here is a object I retrieved from the ActiveRecord other = [#<Referrer id: 16, name: "Other", published: true, created_at: "2011-07-11 16:22:00", updated_at: "2011-07-11 16:22:00">] Why can't I do other.created_at while I can do other.name?

下面是模型：

class Referrer < ActiveRecord::Base
end

我收到的错误：

The error I'm getting:

NoMethodError: undefined method `created_at' for #<ActiveRecord::Relation:0x1035763c8>

我有什么遗漏？

What have I missed?

推荐答案

如果你会发现，等实际上是一个的ActiveRecord ::关系这基本上意味着它的作用就像引荐对象的数组。所以你不能只是叫 created_at 就可以了。你可以称之为 other.first.created_at 或者如果你想 created_at 的数组日期，你可以做 other.map（安培;：created_at）

If you'll notice, other is actually an ActiveRecord::Relation which basically means it's acting like an array of Referrer objects. So you can't just call created_at on it. You could call other.first.created_at or if you want an array of created_at dates you could do other.map(&:created_at).

您可以致电 other.name 的原因是因为的ActiveRecord ::关联响应名。但它是一个不同的名称方法比你的推荐人的名称属性模式。 other.name 应该返回推荐人而不是其他吧？

The reason you can call other.name is because an ActiveRecord::Relation responds to name. But it's a different name method than the name attribute on your Referrer model. other.name should return "Referrer" instead of "Other" right?

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