Understanding email link in rodauth mailer

[pozzos]

Hello!

I'm trying to customise the format of the links sent by rodauth's mailer, and there are a few lines I can't find documentation on. Since I have a JSON API, I need to redirect all these links to custom pages I have made that do AJAX calls.

For the account verification, modification seems easy (simply replace rodauth.verify_account_url with a custom function)

however for the others, there is an "email_link" function that seems to seems to set instance variables on rodauth. How does this work, and how could I go about modifying the format?

Apologies if this is an obvious question.

Best regards,
Sebastian

[janko]

Hi, it's not an obvious question at all 😉 The Action Mailer design is still something I'm iterating on, since there is no official recommendation in Rodauth itself on how best to background emails.

I modified the RodauthMailer class in the demo app to keep the Rodauth instance. Rodauth doesn't seem to currently provide an easy way to get the email token, so you could create a wrapper method:

# app/misc/rodauth_main.rb
class RodauthMain < Rodauth::Rails::Auth
  configure do
    # ...
  end

  def verify_account_email_token
    token_param_value(verify_account_key_value)
  end
end

In your RodauthMailer, you could then build the frontend URL:

class RodauthMailer < ApplicationMailer
  def verify_account(name, account_id, key)
    @rodauth = rodauth(name, account_id) { @verify_account_key_value = key }
    @email_link = "https://frontend.example.com/verify-account?token=#{@rodauth.verify_account_email_token}"
    # ...
  end
end

Let me know if this works 😉 I think it would be useful to make the token_param_value Rodauth method public, I'll propose that to Jeremy.

[pozzos]

Dear Janko,

Thanks for such a detailed answer! I will try that and let you know how it goes.

Best regards,
Sebastian

[crespire]

The code provided for the mailer did not initially work. I changed it to this snippet which worked. I think it has to do with trying to pass in the account_id into the rodauth private method, which only takes name.

def verify_account(name, account_id, key)
  @rodauth = rodauth(name)
  @rodauth.instance_variable_set(:@account, { id: account_id })
  @rodauth.instance_variable_set(:@verify_account_key_value, key)
  @email_link = "https://localhost:3001/verify-account/#{@rodauth.verify_account_email_token}"
    # rest of code
end

[janko]

@crespire Yes, that code I posted works on a modified RodauthMailer that I recently pushed to the Rails demo repository.

[crespire]

This was helpful. I suppose if we wanted to verify other elements of the account, we would have to define the appropriate instance variable on @rodauth?

For example, if a user changed their login, then we'd have to define verify_login_change_key_value and use that to link to the front end. Similarly, it looks like for "Forgot Password" functionality, the variable would be get_reset_password_key(id) that we'd have to put in the link to the front end.

Just want to make sure I understand, thanks!

[pboling]

To generate different links, you could override the corresponding *_email_link configuration method.

I'm want to do exactly that, but I don't know how. The problem is I can't call super, and I can't find the definition of the *_link methods anywhere; I assume their are defined dynamically?

    verify_account_email_link do
      byebug
      super
    end

I am trying to figure out how to build my alternate version of a link (with a path key for path-based multi-tenant support).

Note: calling super gives:

#<RuntimeError: implicit argument passing of super from method defined by define_method() is not supported. Specify all arguments explicitly.>

which is the dead giveaway for metaprogramming 😆

[pboling]

I figured it out!

    verify_account_email_link do
      segs = verify_account_url(key: @verify_account_key_value).split('/')
      segs.insert(-2, request.env[:path_key])
      segs.join('/')
    end

And I end up with a URL which in testing env looks like: :https:///multi/tenant/verify-account?key=3Aqg_sQut52kW1NvUtrm2dpkLMvdjbTtKs5JVKrLOBE, which is exactly what I am looking for!

[janko]

Yeah, there is metaprogramming involved. The verify_account feature defines a default verify_account_email_link method on the Rodauth object. The verify_account_email_link configuration method exists to override that method, and that uses define_method internally. That configuration method is basically implemented like this:

def verify_account_email_link(&block)
  @auth.define_method(:verify_account_email_link, &block)
end

Given that the block passed to verify_account_email_link is forwarded to define_method, Ruby requires you to call super with parentheses. If there are no arguments, then you need to specify empty parentheses:

verify_account_email_link do
  byebug
  super()
end

[pboling]

Thanks! I have all that working, however, now when the test (I'm setting this up inside teh gem's test suite) is failing after visiting the link generated link.

I added a prefixed method to the test_helper.rb, to assist on the test side:

  def prefixed(path_key: nil, prefix: nil)
    [prefix, path_key].compact.select {|x| !x.empty? }.join("/")
  end

I am here now:

   67:     if verify
   68:       email = ActionMailer::Base.deliveries.last
   69:       verify_account_link = email.body.to_s[%r{#{prefixed(path_key: path_key, prefix: prefix)}/verify-account\S+}]
   70:       byebug
=> 71:       visit verify_account_link
   72:       click_on "Verify Account"
   73:     end

and I have this:

(byebug) verify_account_link
"/multi/tenant/kiwi/verify-account?key=Tkva-IFqky8i-73klUUCAiX5MVucfudvYzvS8b36e5c"
(byebug) visit verify_account_link
*** ActionController::RoutingError Exception: No route matches [GET] "/multi/tenant/login"

nil

I can't figure out where that login link is being generated, but regardless it is obvious that I must also override all the *_path methods to include the path key... and I'm not sure how to do that.

[janko]

It's difficult to tell what's going on with just bits and pieces. It's probably best to continue in #257, which is still pending my reply. I'm currently trying to solve a similar problem – generating localized routes (jeremyevans/rodauth#380) – so I wanted to use knowledge from that to make better suggestions.

[crespire]

I wanted to check back in. I have updated my application to use the reference mailer implementation (seen in the rails example app) as I ended up needing to modify more than just one mail link (initially, I was only concerned about account verify, but now I am working on password reset and login change).

Thank you so much for your conversations here, I updated the implementation without any issues on the latest rodauth-rails gem version!