Orden

A simple library (~ 40 LOC) to generate sorting links via query strings for example: http://www.example.com/?sort_attr=id&sort_dir=asc.

The only dependency of this library is Rack so it should work in your Rack compatible framework of choice (Cuba, Rails, Roda, Sinatra, etc).

The typical use case for the library is column sorting on html tables.

Add this line to your application's Gemfile:

gem 'orden'

And then execute:

$ bundle

Or install it yourself as:

$ gem install orden

You need to instantiate an Orden object in the context of the current request, for this you need to pass a Rack::Request or similiar (Roda typical 'r' object, request object inside a Rails controller, etc).

Orden.new([request_object], [default sort attr], [default order (asc/desc)])

For example:

@sorter = Orden.new(r, "id", "desc")

In your views you can now call:

@sorter.sort_path([attr])

For example in a table header:

<th><a href="<%= @sorter.sort_path "id" %>">ID</a></th>
<th><a href="<%= @sorter.sort_path "name" %>">Name</a></th>

and it will generate the expected path to sort your results using that attribute for example (/users?sort_attr=id&sort_dir=asc).

Take into account that this library does not apply any type of sanitation to the received parameters. Typically sorting attributes should be filtered or white listed someway before applying them to an SQL query or equivalent.

For example you can create a helper such as:

module SortHelper
  def sort_sql(sorter, attr_whitelist)
    if attr_whitelist.include?(sorter.current_attribute)
      "#{sorter.current_attribute} #{sorter.current_direction}"
    else
      "#{sorter.default_attr} #{sorter.default_dir}"
    end
  end
end

and the use it in an ActiveRecord query:

@sorter = Orden.new(req, "id", "desc")
@users = User.order(sort_sql(@sorter, User::SORTABLE_ATTRIBUTES)).

Please take this as an example, this code may not be secure.

Bug reports and pull requests are welcome on GitHub at https://github.com/manuca/orden.