By requiring the ruby modules ‘rss’, ‘open-uri’ we can fetch, format and display track info from Last.fm.
Last.fm does not provide a user’s Top Weekly Tracks in RSS format, so we need to also require ‘hpricot’ and parse the XML.
Here are some classes I coded which are later called in a Sinatra helper and eventually the returned data is exposed in a view. You can see this in action here.
require 'rubygems'
require 'hpricot'
require 'open-uri'
require 'rss'
class LastfmWeeklyTracksXML
def initialize(username)
@un = username
@url = "http://ws.audioscrobbler.com/2.0/user/#{@un}/weeklytrackchart.xml"
@data = []
end
# build an array of track info using xml data
def get_the_data
@doc = Hpricot.XML(open(@url))
(@doc/:track).each do |track|
t = { :artist => track.at("artist").innerHTML, :song => track.at("name").innerHTML, :url => "http://" + track.at("url").innerHTML,:plays => track.at("playcount").innerHTML}
@data.push(t)
end
return @data
end
end
class Feed
def initialize(url)
@url = url
@data = []
end
def read_feed
@document = open(@url).read
rss = RSS::Parser.parse(@document)
rss.items.each do |item|
@data.push({ :title => item.title, :url => item.link})
end
return @data
end
end
Helper code
# call this from the route in app.rb
# either helpers or routes has to inherit the
# classes for getting Last.FM xml and rss data
def last_fm_info(datatype,username)
case datatype
when "loved"
url = "http://ws.audioscrobbler.com/2.0/user/#{username}/lovedtracks.rss"
f = Feed.new(url)
f.read_feed
when "recent"
url = "http://ws.audioscrobbler.com/1.0/user/#{username}/recenttracks.rss"
f = Feed.new(url)
f.read_feed
when "top-weekly"
url = "http://ws.audioscrobbler.com/2.0/user/#{username}/weeklytrackchart.xml"
f = LastfmWeeklyTracksXML.new(username)
f.get_the_data
end
end
Code for Sinatra route
# this code would be in your app.rb file
post '/demo/last-fm' do
datatype = params[:type]
username = params["lastfm-un"]
if datatype == "top-weekly"
@weekly = last_fm_info(datatype,username)
else
@tracks = last_fm_info(datatype,username)
end
@type = datatype.gsub("-"," ")
erb :lastfm
end
