# Standalone Usage in Sinatra

Padrino is by default a full-stack framework which provides a large number of
enhancements to Sinatra and uses a new base application `Padrino::Application`.
However, there are clearly times when even Padrino itself is far too
'heavyweight' for an application.

In these instances, the ideal situation would be to cherry-pick individual
enhancements and use them in your existing Sinatra application. Fortunately,
Padrino is committed to allowing you to do exactly that! Each major component
within Padrino can be used in isolation and applied to an existing Sinatra
application. This guide will walk you through that process for each component.
You can also find some examples
[here](https://github.com/padrino/padrino-integration/tree/master/fixtures/single-apps
"link to padrino single-apps").

--------------------------------------------------------------------------------

## Padrino Helpers

This component provides a great deal of view helpers related to html markup
generation. There are helpers for generating tags, forms, links, images, and
more. Most of the basic methods should be very familiar to anyone who has used
rails view helpers.

You can check out the details of these helpers in the
[Application Helpers](/guides/application-helpers/overview "Application Helpers guide")
guide. To register these helpers within your Sinatra application:

```ruby
# app.rb
require 'sinatra/base'
require 'padrino-helpers'

class Application < Sinatra::Base
  register Padrino::Helpers
end
```

--------------------------------------------------------------------------------

## Padrino Mailer

This component provides a powerful but simple mail delivery system within
Padrino (and Sinatra). There is full support for using an html content type as
well as for file attachments. The Padrino Mailer has many similarities to
ActionMailer but is much lighter-weight and easier to use.

You can check out the details of the mailer in the
[Padrino Mailer](/guides/features/padrino-mailer "Padrino Mailer guide") guide. To
register this mailer within your Sinatra application:

```ruby
# app.rb
require 'sinatra/base'
require 'padrino-mailer'

class Application < Sinatra::Base
  register Padrino::Mailer

  mailer :sample do
    email :birthday do |name, age|
      subject 'Happy Birthday!'
      to      'john@fake.com'
      from    'noreply@birthday.com'
      locals  name: name, age: age
      render  'sample/birthday'
    end
  end
end
```

--------------------------------------------------------------------------------

## Padrino Routing

You can check out the details of the routing system in the
[Routing](/guides/controllers/routing "Routing") guide. To register the routing and controller
functionality within your Sinatra application:

```ruby
# app.rb
require 'sinatra/base'
require 'padrino-core/application/routing'
#
# Small example that show you some padrino routes.
# Point your browser to:
#
#   http://localhost:3000
#   http://localhost:3000/bar
#   http://localhost:3000/bar.js
#   http://localhost:3000/custom-route/123
#
# These routes didn't work:
#
#   http://localhost:3000/bar.xml
#   http://localhost:3000/bar.jsl
#   http://localhost:3000/custom-route
#
class MyApp < Sinatra::Application
  register Padrino::Routing

  get :foo, map: '/' do
    'This is foo mapped as index'
  end

  get :bar, provides: [:js, :html] do
    case content_type
      when :js   then 'Bar for js'
      when :html then 'Bar for html'
      else 'You can never see this'
    end
  end

  get :custom, map: '/custom-route', with: :id do
    "This is a custom route with #{params[:id]} as params[:id]"
  end
end # MyApp

MyApp.run!(port: 3000)
```

--------------------------------------------------------------------------------

## Padrino Rendering

Padrino enhances the Sinatra 'render' method to have support for automatic
template engine detection, among other more advanced features.

```ruby
# app.rb
require 'sinatra/base'
require 'padrino-helpers'

class Application < Sinatra::Base
  register Padrino::Rendering

  get('/') { render 'example/demo' } # Auto-renders 'views/example/demo.haml'
  get('/demo') { render :haml, 'example/demo' } # Renders 'views/example/demo.haml'
end
```

--------------------------------------------------------------------------------

## Padrino Cache

Padrino-cache provides page and fragment caching via
[Moneta](http://rubydoc.info/gems/moneta) backends.

```ruby
# app.rb
require 'sinatra/base'
require 'padrino-cache'

class Application < Sinatra::Base
  register Padrino::Cache
end
```

This will allow for use of the caching functionality within Sinatra.