Class: Scrobbler::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/scrobbler/base.rb

Direct Known Subclasses

Authentication, BaseXml, Geo, Library, Radio, Track, Venue

Constant Summary

@@cache =

By default, there is no cache

[]

Class Method Summary (collapse)

Instance Method Summary (collapse)

Class Method Details

+ (void) add_cache(cache)

This method returns an undefined value.

Add a cache provider to the caching system



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# File 'lib/scrobbler/base.rb', line 28

def Base.add_cache(cache)
  @@cache << cache
end

+ (void) api_key=(api_key)

This method returns an undefined value.

Set the default API key.

This key will be used by all Scrobbler classes and objects.



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# File 'lib/scrobbler/base.rb', line 38

def Base.api_key=(api_key)
  @@api_key = api_key
end

+ (String) fetch_http(request_method, paramlist)

Fetch a http answer for the given request



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# File 'lib/scrobbler/base.rb', line 129

def Base.fetch_http(request_method, paramlist)
  url = URI.join(API_URL, "/2.0/?#{paramlist.join('&')}")
  case request_method.downcase
    when "get"
      req = Net::HTTP::Get.new(url.request_uri)
    when "post"
      req = Net::HTTP::Post.new(url.request_uri)
  end
  http = Net::HTTP.new(url.host, url.port)
  http.use_ssl = (url.port == 443)
  xml = http.start() do |conn|
    conn.request(req)
  end
  xml.body
end

+ (Array<Scrobbler::Base>) get(api_method, parent, element, parameters = {})

Initiate a API and parse it.



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# File 'lib/scrobbler/base.rb', line 67

def Base.get(api_method, parent, element, parameters = {})
  scrobbler_class = element
  element = element.to_s.sub("Scrobbler::","").downcase
  doc = request(api_method, parameters)
  elements = []
  doc.root.children.each do |child|
      next unless child.name == parent.to_s
      child.children.each do |child2|
          next unless child2.name == element
          begin
            elements << scrobbler_class.new_from_libxml(child2)
          rescue
            # Sadly last.fm does not always return valid Elements
            # @todo Try to make the best out of it
          end
      end
  end unless doc.root.nil? || doc.root.children.nil?
  elements
end

+ (String) load_from_cache(parameters)

Load a request from cache if possible



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# File 'lib/scrobbler/base.rb', line 100

def Base.load_from_cache(parameters)
  found = nil
  @@cache.each do |cache|
    if cache.has?(parameters)
      found = cache.get(parameters)
      break
    end
  end
  found
end

+ (LibXML::XML::Document) post_request(api_method, parameters = {})

Execute a request to the Audioscrobbler webservice



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# File 'lib/scrobbler/base.rb', line 92

def Base.post_request(api_method, parameters = {})
  Base.request(api_method, parameters, 'post')
end

+ (LibXML::XML::Document) request(api_method, parameters = {}, request_method = 'get')

Execute a request to the Audioscrobbler webservice

Raises:

  • (ArgumentError)


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# File 'lib/scrobbler/base.rb', line 151

def Base.request(api_method, parameters = {}, request_method = 'get')
  raise ArgumentError unless [String, Symbol].member?(api_method.class)
  raise ArgumentError unless parameters.kind_of?(Hash)

  parameters = {:signed => false}.merge(parameters)
  parameters['api_key'] = @@api_key
  parameters['method'] = api_method.to_s
  check_cache = false
  paramlist = []
  # Check if we want a signed call and pop :signed
  if parameters.delete :signed
    #1: Sort alphabetically
    params = parameters.sort{|a,b| a.at(0).to_s<=>b.at(0).to_s}
    #2: concat them into one string
    str = params.join('')
    #3: Append secret
    str = str + @@secret
    #4: Make a md5 hash
    md5 = Digest::MD5.hexdigest(str)
    params << [:api_sig, md5]
    params.each do |a|
      paramlist << "#{sanitize(a.at(0))}=#{sanitize(a.at(1))}"
    end
  else
    if request_method == 'get' then
      check_cache = true
    end
    parameters.each do |key, value|
      paramlist << "#{sanitize(key)}=#{sanitize(value)}"
    end
  end

  xml = nil
  # Check if we could read from cache
  xml = load_from_cache(parameters) if check_cache
  # Fetch the http answer if cache was empty
  xml = fetch_http(request_method, paramlist) if xml.nil?
  # Process it
  doc = Nokogiri::XML(xml) { |config| config.noent.noblanks.nonet }
  # Validate it
  validate_response_document doc
  # Write to cache
  save_to_cache(xml, parameters) if check_cache

  # Return the parsed result
  doc
end

+ (String) sanitize(param)

Clean up a URL parameter.



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# File 'lib/scrobbler/base.rb', line 56

def Base.sanitize(param)
  URI.escape(param.to_s, Regexp.new("[^#{URI::PATTERN::UNRESERVED}]"))
end

+ (void) save_to_cache(xml, parameters)

This method returns an undefined value.

Save a request answer to all caches that would store it.



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# File 'lib/scrobbler/base.rb', line 116

def Base.save_to_cache(xml, parameters)
  @@cache.each do |cache|
    if cache.writable? then
      cache.set(xml, parameters)
    end
  end
end

+ (void) secret=(secret)

This method returns an undefined value.

Set the default API secret.

This secret will be used by all Scrobbler classes and objects.



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# File 'lib/scrobbler/base.rb', line 48

def Base.secret=(secret)
  @@secret = secret
end

+ (void) validate_response_document(document)

This method returns an undefined value.

Check response status, raise ApiError if request failed.



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# File 'lib/scrobbler/base.rb', line 203

def Base.validate_response_document(document)
  unless document.root and document.root['status'] == 'ok'
    error_message = (document.content if document.root.child.name == 'error') rescue "Erroneous documents received"
    raise ApiError, error_message
  end
end

Instance Method Details

- (Array) call(api_method, parent, element, params)

Call a API method



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# File 'lib/scrobbler/base.rb', line 276

def call(api_method, parent, element, params)
  Base.get(api_method, parent, element, params)
end

- (Array) call_pageable(method, parent, element, options = {})

Generic request method for the most Library funtions



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# File 'lib/scrobbler/base.rb', line 237

def call_pageable(method, parent, element, options={})
  options = {:all => true}.merge options
  result = []
  if options.delete(:all)
    doc = Base.request(method, options.merge(:page => 1))
    root = nil
    doc.root.children.each do |child|
      next unless child.name == parent.to_s
      root = child
    end unless doc.nil? || doc.root.nil?
    if root.nil? then
      # Sometimes Last.fm returns an empty file if we query for sth not known
      return []
    end
    #return nil if root.nil? # Sometimes Last.fm returns an empty XML file if there were no artists
    total_pages = root['totalPages'].to_i
    root.children.each do |child|
      next unless child.name == element.to_s.sub("Scrobbler::","").downcase
      result << element.new_from_libxml(child)
    end
    (2..total_pages).each do |i|
      options[:page] = i
      result.concat call(method, parent, element, options)
    end
  else
    result = call(method, parent, element, options)
  end
  result
end

- (void) populate_data(data = {})

This method returns an undefined value.

Load information into instance variables.



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# File 'lib/scrobbler/base.rb', line 214

def populate_data(data = {})
  data.each do |key, value|
    instance_variable_set("@#{key.to_s}", value)
  end
end

- (LibXML::XML::Document) request(api_method, parameters = {}, request_method = 'get')

Execute a request to the Audioscrobbler webservice



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# File 'lib/scrobbler/base.rb', line 225

def request(api_method, parameters = {}, request_method = 'get')
  Base.request(api_method, parameters, request_method)
end