#277 Mountable Engines

Aug 01, 2011 | 13 minutes | Rails 3.1

Engines are receiving a major update in Rails 3.1. You can mount them at any path, embed assets, run generators and more. See how in this episode.

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          bash
                
        rails -v
rails plugin new uhoh --mountable
rails g controller failures index
rails g model failure message:text
rake db:migrate
rake uhoh:install:migrations
cd test/dummy
rails g controller simulate failure
        
        
        
        
        
        
        
        
        
      
rails -v
rails plugin new uhoh --mountable
rails g controller failures index
rails g model failure message:text
rake db:migrate
rake uhoh:install:migrations
cd test/dummy
rails g controller simulate failure

          uhoh/failures_controller.rb
                
        module Uhoh
  class FailuresController < ApplicationController
    def index
      @failures = Failure.all
    end
  end
end
        
module Uhoh
  class FailuresController < ApplicationController
    def index
      @failures = Failure.all
    end
  end
end

          uhoh/failures/index.html.erb
                
        <%= image_tag "uhoh/alert.png" %>

<h1>Failures</h1>
<ul>
  <% for failure in @failures %>
    <li><%= failure.message %></li>
  <% end %>
</ul>

<p><%= link_to "Failures", root_url %></p>
<p><%= link_to "Simulate Failure", main_app.simulate_failure_path %></p>
        
<%= image_tag "uhoh/alert.png" %>

<h1>Failures</h1>
<ul>
  <% for failure in @failures %>
    <li><%= failure.message %></li>
  <% end %>
</ul>

<p><%= link_to "Failures", root_url %></p>
<p><%= link_to "Simulate Failure", main_app.simulate_failure_path %></p>

          config/routes.rb
                
        root :to => "failures#index"
        
root :to => "failures#index"

          config/initializers/exception_handler.rb
                
        ActiveSupport::Notifications.subscribe "process_action.action_controller" do |name, start, finish, id, payload|
  if payload[:exception]
    name, message = *payload[:exception]
    Uhoh::Failure.create!(:message => message)
  end
end
        
ActiveSupport::Notifications.subscribe "process_action.action_controller" do |name, start, finish, id, payload|
  if payload[:exception]
    name, message = *payload[:exception]
    Uhoh::Failure.create!(:message => message)
  end
end

          test/dummy/config/routes.rb
                
        mount Uhoh::Engine => "/uhoh", :as => "uhoh_engine"
        
mount Uhoh::Engine => "/uhoh", :as => "uhoh_engine"

          test/dummy/app/controllers/simulate_controller.rb
                
        def failure
  # redirect_to uhoh_engine.root_url
  raise "Simulating an exception"
end
        
def failure
  # redirect_to uhoh_engine.root_url
  raise "Simulating an exception"
end