Helpers

The basics

It is ill-advised to create helpers on the root level of your application. They muddy the global namespace, and don't have easy access to the request, response, session or cookie variables.

Instead, use the handy helpers method to install methods on Sinatra::EventContext for use inside events and templates.

Example:

helpers do
  def bar(name)
    "#{name}bar"
  end
end

get '/:name' do
  bar(params[:name])
end

Implemention of rails style partials

Using partials in your views is a great way to keep them clean. Since Sinatra takes the hands off approach to framework design, you'll have to implement a partial handler yourself.

Here is a really basic version:

# Usage: partial :foo
helpers do
  def partial(page, options={})
    haml page, options.merge!(:layout => false)
  end
end

A more advanced version that would handle passing local options, and looping over a hash would look like:

# Render the page once:
# Usage: partial :foo
# 
# foo will be rendered once for each element in the array, passing in a local variable named "foo"
# Usage: partial :foo, :collection => @my_foos    

helpers do
  def partial(template, *args)
    options = args.extract_options!
    options.merge!(:layout => false)
    if collection = options.delete(:collection) then
      collection.inject([]) do |buffer, member|
        buffer << haml(template, options.merge(
                                  :layout => false, 
                                  :locals => {template.to_sym => member}
                                )
                     )
      end.join("\n")
    else
      haml(template, options)
    end
  end
end