ruby-on-rails - Ruby 实例变量在方法内部不可用

Question

我不明白为什么无法从各个邮件程序方法中访问实例变量 @delivery_options...

class UserMailer < ActionMailer::Base

    @delivery_options = {
            user_name: 'foo',
            password: 'bar',
            address: 'smtp.foobar.net'
    }

    def invite_email (email, project)
        logger.debug( @delivery_options ) #WHY IS THIS IS UNDEFINED??
        @project = project

        #THIS WORKS FINE
        mail(to: email, subject: "WORK DAMMIT", delivery_method_options: {
                user_name: 'foo',
                password: 'bar',
                address: 'smtp.foobar.net'
        })

        #THIS FAILS
        #mail(to: email, subject: "WORK DAMMIT", delivery_method_options: @delivery_options)

    end


end

Answer 1

如果这些是“静态”数据，您可以这样做:

class UserMailer < ActionMailer::Base

    DELIVERY_OPTIONS = {
        user_name: 'foo',
        password: 'bar',
        address: 'smtp.foobar.net'
    }

    def invite_email(email, project)
        mail(to: email, subject: "WORK DAMMIT", delivery_method_options: DELIVERY_OPTIONS)
        ...
    end
end

这应该有效。

如果你想使用一个实例变量，你应该这样做:

class UserMailer < ActionMailer::Base

    def initialize
        @delivery_options = {
            user_name: 'foo',
            password: 'bar',
            address: 'smtp.foobar.net'
        }
    end

    def invite_email(email, project)
        mail(to: email, subject: "WORK DAMMIT", delivery_method_options: @delivery_options)
        ...
    end
end

这样，变量就在您使用的 UserMailer 实例上定义了。您的做法是在 UserMail 类上定义一个实例变量。