I would like to avoid duplicating the setup for multiple mailer previews. What is the best way to clean this up?
class MyMailerPreview < ActionMailer::Preview
def email1
setup
mailer.email1
end
def email2
setup
mailer.email2
end
def email3
setup
mailer.email3
end
end
Here are two possible solutions I found:
There is something called preview_interceptors that are used when generating mailer previews, you could add your own like this:
config/environments/development.rb
config.action_mailer.preview_interceptors = :my_setup
test/mailers/previews/my_setup.rb
class MySetup
def self.previewing_email(message)
message.subject = "New subject"
end
end
test/mailers/previews/user_mailer_preview.rb
class UserMailerPreview < ActionMailer::Preview
include ActionMailer::Previews
register_preview_interceptor :my_setup
def welcome_email
UserMailer.with(user: User.first).welcome_email
end
end
The message parameter is an instance of ActionMailer::Parameterized::MessageDelivery, I am not sure everything you can do with it, but you can set some attributes on the email itself.
I couldn't find much documentation on preview interceptors, but here is a link to how they are used in Rails.
# Previews can also be intercepted in a similar manner as deliveries can be by registering
# a preview interceptor that has a <tt>previewing_email</tt> method:
#
# class CssInlineStyler
# def self.previewing_email(message)
# # inline CSS styles
# end
# end
#
# config.action_mailer.preview_interceptors :css_inline_styler
#
# Note that interceptors need to be registered both with <tt>register_interceptor</tt>
# and <tt>register_preview_interceptor</tt> if they should operate on both sending and
# previewing emails.
I tried to include Rails before_action in the class, but it wouldn't hook the methods in the previewer, so the second option I found is to build your own before_action like this:
module MySetup
def before_action(*names)
UserMailer.instance_methods(false).each do |method|
alias_method "old_#{method}", method
define_method method do
names.each do |name|
send(name)
end
send("old_#{method}")
end
end
end
end
class UserMailerPreview < ActionMailer::Preview
extend MySetup
def welcome_email
UserMailer.with(user: User.first).welcome_email
end
before_action :setup
private
def setup
puts "Setting up"
end
end
initialize method.Just override the parent initialize method, call super and then run your setup:
class MyMailerPreview < ActionMailer::Preview
def initialize( params = {} )
super( params )
@email_address = "jules@verne.com"
end
def email1
mailer.email1( @email_address )
end
end
You can view the ActionMailer::Preview.new method here as a reference.
Based on my understanding of what you're asking maybe you could add it into one single method that takes the mailer method as a param
class MyMailerPreview < ActionMailer::Preview
def email_for(emailx) # (Pass the method(email1, etc) as an argument where you're calling it
setup
mailer.send(emailx.to_sym) # Call the method param as a method on the mailer
end
end
Would that work for you?