How can I use Rails mailer with dynamic values?

Question

I am new to Rails and struggling with how to implement dynamic values in my mailer.

The below code all works fine apart from the reply_to which I want a dynamic value but I don't know how to do this.

The params @name, @email, @message are captured on a form and I want the reply_to values to be the same as the params passed from @email.

So, essentially the point of this is someone can book an event and then it will email their details to the event manager who can then just press "reply" and it will reply back to the email the user filled out on the form.

class BookingMailer < ActionMailer::Base
      default from: "notifications@example.com"
      default reply_to: @email

      def contact_mailer(name,email,message)
        @name = name
        @email = email
        @message = message
        mail(to: 'info@example.com', subject: 'Event Booking', reply_to: @email)
      end
    end

I looked on the API docs but they seem to reference users in a database when using dynamic values.

Any help is much appreciated, thanks!

Answer 1

You only set a default value if you wanted to use something for methods that DON'T have an option set (for example, you've set a default from:, so you don't need to set mail(from: "notifications@example.com"...) each time, it'll use the default if not set).

Providing your controller is passing the email address as the second argument then your code should work, although usually I'd pass a booking:

class BookingController < ApplicationController
  def create
    @booking = Booking.new(safe_params)
    if @booking.save
      BookingMailer.contact_mailer(@booking).deliver
    else
      # alarums!
    end
  end
end

Then extract the info you want from that in your mailer:

class BookingMailer < ActionMailer::Base
  default from: 'blah@blah.com'

  def contact_mailer(booking)
    @booking = booking
    mail(to: 'info@example.com', subject: 'Event booking', reply_to: @booking.email)
  end
end

Ideally you should remove the line default reply_to: @email as it's trying to use a class level instance variable @email, instead of the instance variable @email that you intended. For examples on the differences between class variables, instance variables and class instance variables, see here: http://www.railstips.org/blog/archives/2006/11/18/class-and-instance-variables-in-ruby/