Making WillPaginate and Rails to_xml play nice with ActiveResource
This post was written by Scott Davis. Read other posts by Scott Davis.
We are currently working on a project that involves Flex and active resource + will_paginate and we needed to be able to paginate the xml transactions easily. Unfortunately, will_paginate and to_xml don’t play nicely when it comes to adding the current_page, total_pages, and page attributes to the xml. After many failed attempts I went looking around github and found in a few forks of will paginate that some people had solved this problem but, I didn’t want to install another version of the gem to risk breaking other apps on the server so I did it the rails way!
I started by creating a module that opens up the will_paginate collection class and includes ActiveResource and alias method chain the to_xml method to include these values. Example code below.
#enviroment.rb ... require 'to_xml_extensions'
#lib/to_xml_extensions.rb module WillPaginateHelpers include ActiveSupport::CoreExtensions::Array::Conversions def to_xml_with_collection_type(options = {}) serializeable_collection.to_xml_without_collection_type(options) do |xml| xml.tag!(:current_page, {:type => ActiveSupport::CoreExtensions::Hash::Conversions::XML_TYPE_NAMES[current_page.class.name]}, current_page) xml.tag!(:per_page, {:type => ActiveSupport::CoreExtensions::Hash::Conversions::XML_TYPE_NAMES[per_page.class.name]}, per_page) xml.tag!(:total_entries, {:type => ActiveSupport::CoreExtensions::Hash::Conversions::XML_TYPE_NAMES[total_entries.class.name]}, total_entries) end.sub(%{type="array"}, %{type="collection"}) end alias_method_chain :to_xml, :collection_type def serializeable_collection #:nodoc: # Ugly hack because to_xml will not yield the XML Builder object when empty? empty? ? returning(self.clone) { |c| c.instance_eval {|i| def empty?; false; end } } : self end end WillPaginate::Collection.send(:include, WillPaginateHelpers)
This now gives me the proper xml when I call to_xml
<?xml version="1.0" encoding="UTF-8"?> <time-cards type="collection"> <current_page type="integer">1</current_page> <per_page type="integer">25</per_page> <total_entries type="integer">108</total_entries> <time_card> <approved type="boolean">false</approved> <billable type="boolean">false</billable> <created_at type="datetime">2008-10-10T14:04:13-04:00</created_at> <date type="datetime">2008-10-10T14:04:13-04:00</date> <has_been_billed type="boolean">false</has_been_billed> <has_been_paid type="boolean">true</has_been_paid> <hours type="float">2.0</hours> <id type="integer">98</id> <is_overtime type="boolean">false</is_overtime> <task_id type="integer">6</task_id> <updated_at type="datetime">2008-10-10T14:04:13-04:00</updated_at> <user_id type="integer">1</user_id> </time_card> ... </timecards>
About the author: Scott is a 23-year-old Web Developer working at SmartLogic Solutions in Baltimore, Maryland. Languages: Ruby, C, PHP, ColdFusion, ActionScript, Flex
October 11th, 2008 at 3:32 am
Thanks for sharing :) very cool
October 15th, 2008 at 11:35 pm
This is cool. but I find that when I am trying to consume the resource on a client, ActiveResource dies with the error: undefined method `collect!’ for #
Did you have to change the consumer in anyway to read/use the new xml params?
October 16th, 2008 at 10:27 am
Geoff i had to fake a will_paginate collection on the client side … ill post the code todo this later today
October 28th, 2008 at 7:44 pm
[...] Follow up to my other blog post about Paginating an ActiveResource model and to_xml I figured I should include the client side code [...]