Rails:setter 中的 Attr 访问器未定义方法 [英] Rails: Attr accessor undefined method in the setter

问题描述

我在用户模型中有这行代码:

I have this line of code in a User model:

attr_accessor :birthdate

在同一个模型中，我有一个方法尝试通过这样做来设置生日:

In the same model, I have a method that tries to set that birthdate by doing this:

self.birthdate = mydate

其中 mydate 是一个 Date 对象.

Where mydate is a Date object.

我收到此错误:undefined methodbirthdate='

为什么会这样?attr_accessor 不是创建了 setter 和 getter 吗?

Why is this happening? Isn't attr_accessor creates a setter and a getter?

推荐答案

让我猜猜，你是从一个类方法中调用那个 setter，对吧?

Let me guess, you're calling that setter from a class method, right?

class Foo
  attr_accessor :bar

  def set_bar val
    self.bar = val # `self` is an instance of Foo, it has `bar=` method
    bar
  end

  def self.set_bar val
    self.bar = val # here `self` is Foo class object, it does NOT have `bar=`
    bar
  end
end

f = Foo.new
f.set_bar 1 # => 1
Foo.set_bar 2 # => 
# ~> -:10:in `set_bar': undefined method `bar=' for Foo:Class (NoMethodError)

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