# Sinatra Extension: StaticAssets  

Gem *sinatra-static-assets* implements the following helpers methods:

* `image_tag`
* `stylesheet_link_tag`
* `javascript_script_tag`
* `link_tag`

To install it, run:

    sudo gem install wbzyl-sinatra-static-assets -s http://gems.github.com

All these methods are simple wrappers around the `url_for` method 
from the [sinatra-url-for](http://github.com/emk/sinatra-url-for/) gem.

## When will you need it?

Whenever you use the
[Passenger module for Apache2](http://www.modrails.com/documentation/Users%20guide%20Apache.html#deploying_rack_to_sub_uri)
or use `Rack::URLMap` to dispatch an application to
sub URI.

Example: Suppose that we already have a virtual host `hitch.local`
and two Sinatra applications that live in
`/home/me/www/summer` and `/home/me/www/winter` 
directories, respectively.
We want our Sinatra applications to be accessible from 
the following sub URI: 

    http://hitch.local/summer 

and

    http://hitch.local/winter

To configure Apache2 and Passenger to serve our applications
we need to create a new configuration file with the following content:

    <VirtualHost *:80>
      ServerName hitch.local
      DocumentRoot /srv/www/hitch.local
      
      RackBaseURI /summer
      RackBaseURI /winter
    </VirtualHost>

and a link to the applications directories in `/srv/www/hitch.local`:

    ln -s /home/me/www/summer/public /srv/www/hitch.local/summer
    ln -s /home/me/www/winter/public /srv/www/hitch.local/winter

After restarting an Apache2 server and visiting, for example, the first 
application at `http://hitch.local/summer` we see that links to
images, stylesheets and javascripts are broken.

The hitch here is that in Sinatra applications we usually refer to
images/stylesheets/javascripts with absolute URI:

    /images/tatry1.jpg    /stylesheets/app.css    /javascripts/app.js

That setup **works** whenever we are running applications locally.
The absolute URI above tells a browser to request images 
(stylesheets and javascripts) from:

    http://localhost:4567/images/tatry1.jpg

which in turn, tells a server to send a file:

    /home/me/www/summer/public/images/tatry1.jpg

The `public` directory is the default directory where static files
should be served from.
So, the `/images/tatry1.jpg` picture will be there and will be served
unless we had changed that default directory.

But these absolute URIs do not work when, for example,
the *summer* application is dispatched to `/summer` sub URI.
As a result the images are at:

    http://hitch.local/summer/images/tatry1.jpg

but we request them from: 

    http://hitch.local/images/tatry1.jpg

And this **does not work** because there is no application 
dispatched to *images* sub URI.

The recommended way to deal with an absolute URI 
is to use a helper method that automatically converts
`/images/tatry1.jpg` to `/summer/images/tatry1.jpg`
for application dispatched to `/summer` sub URI. 

In the above example you can simply remove the `<img>` 
HTML tag and replace it with a Ruby inline code like this: 

    <%= image_tag("/images/tatry1.jpg", :alt => "Błyszcz, 2159 m") %>

See also, [How to fix broken images/CSS/JavaScript URIs in sub-URI 
deployments](http://www.modrails.com/documentation/Users%20guide%20Apache.html#sub_uri_deployment_uri_fix)

## Usage examples

In HTML `<link>` and `<img>` tags have no end tag.
In XHTML, on the contrary, these tags must be properly closed.

We can choose the appropriate behaviour with *closed* option:

    image_tag "/images/tatry1.jpg", :alt => "Błyszcz, 2159 m", :closed => true

The default value of *closed* option is `false`.

    stylesheet_link_tag "/stylesheets/screen.css", "/stylesheets/summer.css", :media => "projection"
    javascript_script_tag "/javascripts/jquery.js", "/javascripts/summer.js", :charset => "iso-8859-2"
    link_to "Tatry Mountains Rescue Team", "/topr"

In order to use include the following in a Sinatra application: 

    gem 'wbzyl-sinatra-static-assets'
    require 'sinatra/static_assets'

Or, if subclassing `Sinatra::Base`, include helpers manually:

    gem 'wbzyl-sinatra-static-assets'
    require 'sinatra/static_assets'
      
    class Summer < Sinatra::Base
      helpers Sinatra::StaticAssets
      # ...
    end


## Miscellaneous stuff

1. The `examples` directory contains *summer* and *winter* applications.

2. In order to create a virual host add the following to */etc/hosts/*: 

    127.0.0.1       localhost.localdomain localhost hitch.local

3. TODO: write tests