fallenrogue.com

Since this was pretty easy to implement in RoR I thought I would go over some of the finer points of making a call to a REST service in Rails. You may have noticed a new set of images below my tag cloud on the main page. That's the magnoliaBlossom that I threw in. The good people at Ma.gnolia (a social bookmarking service) have just released a new api for it which includes…screenshots of your favorite pages!!! Woo-hoo! So, I figured, why not have an image based blog-roll from magnolia. A feature that they are lovingly calling a Blossom on their site. Here's what I did in Rails to get that sucka working…

First I created a model to represent that class that we were going to be using. I called it MagnoliaBlossom. I know, I know… creative, right?  Anyway, once you've got the model, you can start filling it in. 

#uses the Ma.gnolia API to share images of websites the user has bookmarked.
require 'net/http'
require 'uri'
require 'time'
require 'rexml/document'

class MagnoliaBlossom < ActiveRecord::Base
  include REXML
 
  attr_accessor :bookmarks
 

  #Small Struct that will hold our objects
  class Bookmark < Struct.new(:url, :screenshot, :title, :description)
    def to_s
      "Title: #{@title}"
    end
    def date=(value); super(Time.parse(value)) end
  end
 
  def initialize(limit)
    @limit = limit
    @uri = URI.parse('http://ma.gnolia.com/api/rest/1/bookmarks_find')
    @bookmarks = []
    self.make_the_call
  end
 
  protected
 
  def make_the_call
    res = Net::HTTP.post_form(@uri,{'person'=>ENV['Magnolia_Username'], 'limit'=>@limit, 'api_key'=>ENV['Magnolia_Key']})
    parse(res.body)
  end
 
  def parse(xml_body)
    xml = Document.new(xml_body)
    
    XPath.each(xml, "//bookmarks/bookmark/") do |elem|
     
      bm = Bookmark.new
      bm.url = XPath.match(elem, "url/text()").to_s
      bm.screenshot = XPath.match(elem, "screenshot/text()").to_s
      bm.title = XPath.match(elem, "title/text()").to_s
      bm.description = XPath.match(elem, "description/text()").to_s
      
      @bookmarks << bm
    end
  end
end

Granted, in this example I didn't have to inherit from ActiveRecord in order to get this work. I only do that out of habit these days. A plain Jane class would be just fine. Anyway, in the constructor you can pass this bad boy a value for how many items you'd like to return and presto…you've got a ma.gnolia blossom of your very own.

NOTES: Be sure that you have 2 ENV variables for the username and the API Key that's needed when making calls to Ma.gnolia. Otherwise this whole thing won't work. 

There you have it. A simple way to query a REST service using POST. Please feel free to help me improve this code with comments and questions. Thanks!