Agile Web Development

= acts_as_ordered

If you find this plugin useful, please consider a donation to show your support!

http://www.paypal.com/cgi-bin/webscr?cmd=_send-money

Email address: jonathan.viney@gmail.com

== Instructions

This plugin gives ActiveRecord models an easy way to find their neighbours in a given order.

== Resources

Install

• script/plugin install http://svn.viney.net.nz/things/rails/plugins/acts_as_ordered

== Usage

class Person < ActiveRecord::Base actsas_ordered :order => 'firstname' end

Say you have people with first names of Adam, Jonathan and Robert:

p = Person.findby_firstname('Jonathan')

p.next # Robert p.previous # Adam p.previous.previous # Adam (does not wrap around to end) p.next.next # Robert (does not wrap around to start)

If you want the next and previous methods to wrap around the ends, use:

actsas_ordered :order => 'firstname', :wrap => true

You can also jump by more than one at a time:

# Without wrapping (clamps to ends) p = Person.findby_firstname('Jonathan') p.next(:number => 2) # Robert p.next(:number => 100) # Robert p.previous(:number => 100) # Jonathan

# With wrapping (wraps around ends as many times as you like) p = Person.findby_firstname('Jonathan') p.next(:number => 8) # Adam p.previous(:number => 17) # Robert

You can use this to get the next/previous model that matches some condition:

class Person < ActiveRecord::Base acts_as_ordered :condition => proc { |p| p.age > 10 }

# Or check that a method on the model returns true
acts_as_ordered :conditions => :male?

end

In this case, the next and previous methods will return the closest adjacent object that matches the condition.

You can use this in a application to be able to quickly browse through people. Eg:

class PersonController < ApplicationController def view_neighbour # params[:direction] is passed off the page as 'next' or 'previous' @person = Person.find(params[:id]).find_by_direction(params[:direction]) render :action => 'view' end

# Or alternatively...
def view_next
  @person = Person.find(params[:id]).next
  render :action => 'view'
end

def view_previous
  @person = Person.find(params[:id]).previous
  render :action => 'view'
end

end

Problems, comments, and suggestions all welcome. jonathan.viney@gmail.com

== Credits

Atelier Fabien - Support for :scope => Rick Olson - I borrowed some of the testing code from acts_as_versioned

== Misc

Subversion

• http://svn.viney.net.nz/things/rails/plugins/acts_as_ordered

Owner: Jonathan Viney

Repository: http://svn.viney.net.nz/things/rails/plugins/acts_as_ordered/

License: Rails' (MIT)

Category: Model