Add helpers to Devise Mailer

[Jared Mehle]

How would I go about adding some custom helper methods to only the
Devise mailer. In a standard Rails mailer, you can write:

helper :my_helper

to load a custom helper module for use in the mailer. I've tried
opening up the Devise::Mailer class and adding that, but it doesn't
work. This is likely due to the Devise modules being autoloaded and
not being available at the time I try to insert my helpers.

[Jared Mehle]

I solved my own problem. You need to crack open DeviseMailer (not
Devise::Mailer) to add helpers.

Like so:
DeviseMailer.class_eval do
helper :mailer
end

On Jul 1, 1:58 pm, Jared Mehle <jrme...@gmail.com> wrote:
> How would I go about adding some custom helper methods to only the

> Devisemailer. In a standard Railsmailer, you can write:
>
> helper :my_helper
>

> to load a custom helper module for use in themailer. I've tried
> opening up the Devise::Mailerclass and adding that, but it doesn't

[docgecko]

Hey Jared,

I have tried to change my application.rb file from:

<pre>config.to_prepare do

   Devise::Mailer.class_eval do 

      helper :url 

   end

end</pre>

to:

<pre>config.to_prepare do

   Devise::Mailer.class_eval do 

      helper :url 

   end

end</pre>

and I now get the following error when I try to start my server.

<pre>`const_missing': uninitialized constant TestApp::Application::DeviseMailer</pre>

To get this to work, were you also placing your DeviseMailer code in the config/application.rb file or somewhere else?

Cheers,

D.

[Mike Jarema]

To resolve this issue I've placed the class_eval code at the bottom of my Devise initializer, specifically after the Devise.setup block.

# config/initializers/devise.rb

Devise.setup do |config|

  # ... existing Devise configuration, no modification necessary to include helper(s) ...

end

Devise::Mailer.class_eval do

  helper :mailer # include "MailerHelper", adjust to suit your needs

end

Hope that helps anyone who Googles this.

- Mike

[Christian Gambardella]

works like a charm! thx!

[Brett Lischalk]

I actually had some issues with this class_eval code in development.  It will work for a while and then my helper would stop being found as I am doing development.  I believe the issue may stem from using class_eval instead of instance_eval.

When I started using instance_eval:

Devise::Mailer.instance_eval do

  helper :mailer # include "MailerHelper", adjust to suit your needs

end

My helper would be found consistently.  I think the problem is the class method "helper" needs to be called in the context of the "class object instance"

- Brett

[Michail Karavaev]

I had same issues with instance_eval.
Hope this will help someone.

add this to application.rb

   
 config.to_prepare do

      Devise::Mailer.helper :my_helper

  end