Ruby instance variables not available inside methods

Question

I can't figure out why the instance variable @delivery_options isn't accessible from within the individual mailer methods...

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

Raindal · Accepted Answer · 2013-09-19 17:02:11Z

3

If these are "static" data, you could just do:

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

This should work.

If you want to use an instance variable, you should do something like:

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

This way, the variable is defined on the instance of UserMailer you are using. The way you did it was defining an instance variable on the UserMail class.

edited Sep 19, 2013 at 17:02

answered Sep 19, 2013 at 16:40

Raindal

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2 Comments

emersonthis Over a year ago

Cool. I'm a Ruby n00b but I think your code uses a constant. I'll give it a try. In the mean time, can you explain why the scope of the instance variable doesn't reach into the methods. Is that not normal Ruby practice?

Raindal Over a year ago

Edited my answer to add some explanations.

Veraticus · Accepted Answer · 2013-09-19 19:36:27Z

2

The first instance variable definition (@delivery_options) is available only to the class, not its methods. That's why you're running into this problem. Class variables (@@delivery_options) are available to all methods in a class, but aren't as frequently used because class variables are not inherently thread safe.

All this said, you probably want to use a constant to define these and just reference the constant. Or, even better, set some default delivery options using ActionMailer's default system like so:

class UserMailer < ActionMailer::Base
  default {user_name: 'foo', password: 'bar', address: 'smtp.foobar.net'}

  ...
end

All defaults are applied to every method in the mailer, but overriden by any options you specify locally.

edited Sep 19, 2013 at 19:36

answered Sep 19, 2013 at 16:53

Veraticus

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