require 'rdf'
require 'rdf/ntriples'
module Qa::Authorities
class Discogs::GenericAuthority < Base
include WebServiceBase
include Discogs::DiscogsTranslation
include Discogs::DiscogsUtils
class_attribute :discogs_secret, :discogs_key
attr_accessor :primary_artists, :selected_format, :work_uri, :instance_uri
# @param [String] subauthority to use
def initialize(subauthority)
@subauthority = subauthority
self.primary_artists = []
self.work_uri = "workn1"
self.instance_uri = "instn1"
end
# @param [String] the query
# @param [Class] QA::TermsController
# @return json results
def search(q, tc)
# Discogs distinguishes between masters and releases, where a release represents a specific
# physical or digital object and a master represents a set of similar releases. Use of a
# subauthority (e.g., /qa/search/discogs/master) will target a specific type. Using the "all"
# subauthority will search for both types.
unless discogs_key && discogs_secret
Rails.logger.error "Questioning Authority tried to call Discogs, but no secret and/or key were set."
return []
end
response = json(build_query_url(q, tc))
if tc.params["response_header"] == "true"
response_hash = {}
response_hash["results"] = parse_authority_response(response)
response_hash["response_header"] = build_response_header(response)
return response_hash
end
parse_authority_response(response)
end
# If the subauthority = "all" (though it shouldn't), call the fetch_discogs_results method to determine
# whether the id matches a release or master. And if the requested format is json-ld, call the build_graph
# method in the translation module; otherwise, just return the Discogs json. check the response to
# determine if it should go to the translation module.
#
# @param [String] the Discogs id of the selected item
# @param [Class] QA::TermsController
# @return results in requested format (supports: json, jsonld, n3, ntriples)
def find(id, tc)
response = tc.params["subauthority"].include?("all") ? fetch_discogs_results(id) : json(find_url(id, tc.params["subauthority"]))
self.selected_format = tc.params["format"]
return response if response["message"].present?
return build_graph(response, format: :jsonld) if jsonld?(tc)
return build_graph(response, format: :n3) if n3?(tc)
return build_graph(response, format: :ntriples) if ntriples?(tc)
response
end
# @param [String] the query
# @param [String] the subauthority
# @return [String] the url
def build_query_url(q, tc)
page = nil
per_page = nil
if tc.params["startRecord"].present?
page = (tc.params["startRecord"].to_i - 1) / tc.params["maxRecords"].to_i + 1
per_page = tc.params["maxRecords"]
else
page = tc.params["page"]
per_page = tc.params["per_page"]
end
escaped_q = ERB::Util.url_encode(q)
"https://api.discogs.com/database/search?q=#{escaped_q}&type=#{tc.params['subauthority']}&page=#{page}&per_page=#{per_page}&key=#{discogs_key}&secret=#{discogs_secret}"
end
# @param [String] the id of the selected item
# @param [String] the subauthority
# @return [String] the url
def find_url(id, subauthority)
"https://api.discogs.com/#{subauthority}s/#{id}"
end
private
# In the unusual case that we have an id and the subauthority is "all", we don't know which Discogs url to
# use. If the id is a match for both a release and a master (or neither), return that info as the
# message. Otherwise, return the data for the release or master.
# @param [String] the id of the selected item
# @return json results
def fetch_discogs_results(id)
release_resp = json(find_url(id, "release"))
master_resp = json(find_url(id, "master"))
message_status = check_for_msg_response(release_resp, master_resp)
return { "message" => "Neither a master nor a release matches the requested ID." } if message_status == "no responses"
if message_status == "two responses"
return { "message" => "Both a master and a release match the requested ID.",
"resource_url" => ["https://api.discogs.com/masters/#{id}", "https://api.discogs.com/releases/#{id}"] }
end
return master_resp unless master_resp.key?("message")
# return release_resp unless release_resp.key?("message")
release_resp
end
# @param [Hash] the http response from discogs
# @example returns parsed discogs data with context
# [{
# "uri": "https://www.discogs.com/Frank-Sinatra-And-The-Modernaires-Sorry-Why-Remind-Me/release/4212473",
# "id": "4212473",
# "label": "Frank Sinatra And The Modernaires - Sorry / Why Remind Me",
# "context": [{
# "property": "Image URL",
# "values": ["https://img.discogs.com/1358693671-5430.jpeg.jpg"]
# }, {
# "property": "Year",
# "values": ["1950"]
# }, {
# "property": "Record Labels",
# "values": ["Columbia"]
# }, {
# "property": "Formats",
# "values": ["Shellac", "10\"", "78 RPM"]
# }, {
# "property": "Type",
# "values": ["release"]
# }]
# }]
def parse_authority_response(response)
response['results'].map do |result|
{ 'uri' => build_uri(result),
'id' => result['id'].to_s,
'label' => result['title'].to_s,
'context' => assemble_search_context(result) }
end
end
# @param [Hash] the http response from discogs
# @param [Class] QA::TermsController
# @example returns parsed discogs pagination data
def build_response_header(response)
start_record = (response['pagination']['page'] - 1) * response['pagination']['per_page'] + 1
rh_hash = {}
rh_hash['start_record'] = start_record
rh_hash['requested_records'] = response['pagination']['per_page']
rh_hash['retrieved_records'] = response['results'].length
rh_hash['total_records'] = response['pagination']['items']
rh_hash
end
# @param [Hash] the results hash from the JSON returned by Discogs
def build_uri(result)
result['uri'].present? ? "https://www.discogs.com" + result['uri'].to_s : result['resource_url'].to_s
end
# @param [Hash] the results hash from the JSON returned by Discogs
def assemble_search_context(result)
[{ "property" => "Image URL", "values" => get_context_for_string(result['cover_image']) },
{ "property" => "Year", "values" => get_context_for_string(result['year']) },
{ "property" => "Record Labels", "values" => get_context_for_array(result['label']) },
{ "property" => "Formats", "values" => get_context_for_array(result['format']) },
{ "property" => "Type", "values" => get_context_for_string(result['type']) }]
end
# checks if the param is null, returns appropriate value
# @param [String] returns an empty string if item is not presentr
def get_context_for_string(item)
[item.present? ? item.to_s : ""]
end
# checks if the param is null, returns appropriate value
# @param [Array] returns an empty array if item is not presentr
def get_context_for_array(item)
item.present? ? item : [""]
end
end
end