GoogleAnalyticsMailer

This gem automatically rewrites absolute links generated by ActionMailer. It intercepts all'url_for calls (so link_to calls are intercepted as well) and change the final url to add Custom Campaign parameters to your URLs.

Add this line to your application's Gemfile:

gem 'google_analytics_mailer'

And then execute:

$ bundle

Or install it yourself as:

$ gem install google_analytics_mailer

There are three level of customization for rewritten links:

• Class level: Params specified at class level will appear on every link of every message generated by that class
• Method level: Params specified at method level will appear only on that message
• View level: Views level parameters will take the highest precedence and they will always override all the others

In order to enable Google Analytics params for a given mailer you should simply add a line to a given mailer as in:

class UserMailer < ActionMailer::Base
  default :from => 'no-reply@example.com'

  # declare url parameters for this mailer
  google_analytics_mailer utm_source: 'newsletter', utm_medium: 'email' # etc

  # Links in this email will have all links with GA params automatically inserted
  def welcome
    mail(to: 'user@example.com')
  end
end

Then in your view generate links as usual:

<!-- this will produce your-url?utm_medium=email&utm_source=newsletter because of class default params -->
<%= link_to('Read online', newsletter_url) -%>
<!-- local parameters are not overridden, so this produces ?utm_medium=email&utm_source=my_newsletter -->
<%= link_to('Read online', newsletter_url(utm_source: 'my_newsletter')) -%>

In order to override params for a specific message you can override params in the method which defines the message as in:

class UserMailer < ActionMailer::Base
  default :from => 'no-reply@example.com'

  # declare url parameters for this mailer
  google_analytics_mailer utm_source: 'newsletter', utm_medium: 'email' # etc

  # Links in this email will have utm_source equal to second_newsletter
  def welcome
    google_analytics_params(utm_source: 'second_newsletter', utm_term: 'welcome2')
    mail(to: 'user@example.com')
  end
end

At view level you can override generated parameters using the with_google_analytics_params method

<div class="footer">
  <%= with_google_analytics_params(utm_term: 'footer') do -%>
    <!-- this will override other params and produces ?utm_medium=email&utm_source=newsletter&utm_term=footer -->
    <%= link_to('Read online', newsletter_url) -%>
  <%- end -%>
</div>

or you can disable them for a specific block

<div class="footer">
  <%= without_google_analytics_params do -%>
    <!-- this will output link with no analytics params at all -->
    <%= link_to('Read online', newsletter_url) -%>
  <%- end -%>
</div>

Since ActionMailer and ActionController use the same code base to provide view rendering this gem can be used in the same way in any action controller which inherits from ActionController::Base (i.e. almost every controller in a Rails application). The alias google_analytics_controller is provided for better naming thus in a controller you can do

class UserController < ApplicationController

  # declare url parameters for this controller. Absolute links in this controller will be tagged with GA parameters
  google_analytics_controller utm_source: 'some site', utm_medium: 'web' # etc

  # Override for single action
  def index
    google_analytics_params(utm_source: 'index page', utm_term: 'foo bar')
  end
end

View syntax is obviously the same as in mailer.

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request