Rails helper for automatically generating mixpanel tracking for links.

application.html.erb

<!-- Include Mixpanel and init before this. -->

<!-- Place at the bottom of your layout (ex: app/views/layouts/application.html.erb) -->
<% if content_for :mixpanel %>
  <%= javascript_tag(yield :mixpanel) %>
<% end %>

mixpanel_helper.rb

# app/helpers/mixpanel_helper.rb
module MixpanelHelper
  # This should only be used with server-side data, no user input.
  def track_links(selector, name, properties)
    if properties.nil?
      js = "mixpanel.track_links('#{selector}', '#{name}');"
    else
      js = "mixpanel.track_links('#{selector}', '#{name}', #{properties.to_json});"
    end

    content_for :mixpanel do
      js.html_safe
    end
  end
end

module ActionView::Helpers::UrlHelper
  include MixpanelHelper

  # Used to generate unique IDs for tracked links. These are reset with each request.
  def next_uid
    @rand_hex = SecureRandom.hex(4) if @rand_hex.nil?
    @unique_count = 0 if @unique_count.nil?
    @unique_count += 1
    "mp-#{@rand_hex}-#{@unique_count}"
  end

  # Aliased so that we can still call ActionView's link_to helper.
  alias_method :old_link_to, :link_to unless method_defined? :old_link_to
  # Overrides the default `link_to` helper to allow generation of Mixpanel tracking JS.
  # You are not required to provide an ID. Usage:
  #
  #     link_to "My link", my_path, event: {name: "required", selector: ".optional",
  #         properties: {optional: true, "this is awesome" => "duh"}}
  def link_to(*args, &block)
    if block_given?
      name         = capture(&block)
      options      = args[0] || {}
      html_options = args[1] || {}
    else
      name         = args[0]
      options      = args[1] || {}
      html_options = args[2] || {}
    end

    event = html_options.delete(:event) || {}
    if event[:selector].nil? && html_options[:id].nil? && !event[:name].nil?
      html_options[:id] = next_uid
    end
    link_tag = old_link_to(name, options, html_options)

    unless event[:name].nil?
      track_links("#{event[:selector] || '#' + html_options[:id]}", event[:name], event[:properties])
    end

    link_tag
  end
end

view.html

<!-- Below is what will be generated by the new link_to helper. -->
<a href="/my_path" id="mp-07c6f089-2">My link</a>
<script type="text/javascript">
  mixpanel.track_links("#mp-07c6f089-2", "clicked my link", {resource_id: 2});
</script>

view.html.erb

<!-- Place this in any view to track the link to automatically generate the appropriate JS.
    'properties' hash will be passed to mixpanel as a JSON object -->
<%= link_to "My link", my_path, event: {name: "clicked my link",
    properties: {resource_id: resource.id}} %>