Skinning your entire Rails app

Posted by unixmonkey on September 18, 2007

Say I want to deploy my app as a service to several good customers, but I want my app to share the exact layout as each customer site, so it appears to be an internal app to their company and its own clients. I take thier CSS and HTML markup, and make it into a template to wrap around my app’s content.

When I took to task to replicate that functionality in Ruby on Rails, I wasn’t certain would be easily accomplished. All the tutorials I’ve read list template switching as purely CSS affairs. Using CSS to change the presentation of your site is a fine thing, but isn’t enough if you are looking to completely copy the look and feel of a client’s website with your app dropped in.

It took some thought and a little help from the community.

Previously, the system I was used to accepted a site variable passed with the login form that told which template to render. like http://myapp.com/?site=ibm

That’s ugly and really obvious to what it is doing, but what other way is there to know which template to render?

I recall setting up accounts at a handful of sites that were in the format of: http://myusername.myapp.com

This is known as using a subdomain as an account key. Luckily, there is a very simple plugin to set that up in Rails http://wiki.rubyonrails.org/rails/pages/HowToUseSubdomainsAsAccountKeys

After setting up the plugin, I’m able to access the subdomain name anywhere in the app. Good thing, because I need to access it in application.rhtml (or .haml)

 
<% # if there's a subdomain, render the partial of the same name -%>
<% if account_subdomain -%>
    <% # first check to make sure account_subdomain is valid and in accounts table  -%>
    <% @account = Account.find_by_username(account_subdomain) -%>
    <% unless @account.nil? -%>
        <%= render :partial => "layouts/"+account_subdomain %>
    <% else -%>
        <% # There's a subdomain, but it isn't valid. Render default template -%>
        <%= render :partial => "layouts/default" %>
    <% end -%>
<% else -%>
    <%= render :partial => "layouts/default" %>
<% end -%>

Notice in the above, that there are no :yield statements. That’s because :yield can live in a partial too. I’ve set up a partial for each subdomain listed in my database in app/views/layouts, and added some logic to render the default layout when a subdomain either isn’t present or is invalid.