未定义邮件时，如何在邮件程序上调用类方法? [英] How can you call class methods on mailers when they're not defined as such?

问题描述

在Rails中发送邮件时，通常会执行以下操作:

When sending mail in Rails, usually one would do something like this:

UserMailer.password_reset(user).deliver

但是，如果我们查看UserMailer的内部，我们会看到:

But if we look inside UserMailer we can see this:

def password_reset(user) # not self.password_reset
  # ...
end

请注意，方法名称不带self前缀.看起来，您似乎需要首先实例化该对象，如下所示. Rails如何做到这一点?

Notice that the method name is not prefixed with self. Looking at it, it seems like you need to instantiate the object first as below. How does Rails do this?

UserMailer.new.password_reset(user).deliver

推荐答案

这是一个很好的问题.在源代码中( https://github.com/rails/rails/blob/master/actionmailer/lib/action_mailer/base.rb )，Rails使用method_missing创建ActionMailer的新实例.这是源代码中的相关摘录:

That's a great question. In the source (https://github.com/rails/rails/blob/master/actionmailer/lib/action_mailer/base.rb), Rails uses method_missing to create a new instance of the ActionMailer. Here's the relevant excerpt from the source:

def method_missing(method_name, *args) # :nodoc:
  if respond_to?(method_name)
    new(method_name, *args).message
  else
    super
  end
end

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