add language processing to ldpath service

app/services/qa/linked_data/ldpath_service.rb

@@ -4,39 +4,85 @@
 module Qa
   module LinkedData
     class LdpathService
-      VALUE_ON_ERROR = [].freeze
+      LANGUAGE_PATTERN = "*LANG*".freeze
+      PROPERTY_NAME = "property".freeze
 
       class_attribute :predefined_prefixes
       self.predefined_prefixes = Ldpath::Transform.default_prefixes.with_indifferent_access
 
-      # Create the ldpath program for a given ldpath.
-      # @param ldpath [String] ldpath to follow to get a value from a graph (documation: http://marmotta.apache.org/ldpath/language.html)
-      # @param prefixes [Hash] shortcut names for URI prefixes with key = part of predicate that is the same for all terms (e.g. { "madsrdf": "http://www.loc.gov/mads/rdf/v1#" })
-      # @return [Ldpath::Program] an executable program that will extract a value from a graph
-      def self.ldpath_program(ldpath:, prefixes: {})
-        program_code = ""
-        prefixes.each { |key, url| program_code << "@prefix #{key} : <#{url}> \;\n" }
-        program_code << "property = #{ldpath} \;"
-        Ldpath::Program.parse program_code
-      rescue => e
-        Rails.logger.warn("WARNING: #{I18n.t('qa.linked_data.ldpath.parse_logger_error')}... cause: #{e.message}\n   ldpath_program=\n#{program_code}")
-        raise StandardError, I18n.t("qa.linked_data.ldpath.parse_error") + "... cause: #{e.message}"
-      end
+      class << self
+        # Create the ldpath program for a given ldpath.
+        # @param ldpath [String] ldpath to follow to get a value from a graph (documation: http://marmotta.apache.org/ldpath/language.html)
+        # @param prefixes [Hash] shortcut names for URI prefixes with key = part of predicate that is the same for all terms (e.g. { "madsrdf": "http://www.loc.gov/mads/rdf/v1#" })
+        # @param languages [Array<Symbol>] limit results to these languages and anything not tagged (applies to ldpaths with *LANG* marker)
+        # @return [Ldpath::Program] an executable program that will extract a value from a graph
+        def ldpath_program(ldpath:, prefixes: {}, languages: [])
+          program_code = ldpath_program_code(ldpath: ldpath, prefixes: prefixes, languages: languages)
+          Ldpath::Program.parse program_code
+        rescue => e
+          Rails.logger.warn("WARNING: #{I18n.t('qa.linked_data.ldpath.parse_logger_error')}... cause: #{e.message}\n   ldpath_program=\n#{program_code}")
+          raise StandardError, I18n.t("qa.linked_data.ldpath.parse_error") + "... cause: #{e.message}"
+        end
+
+        # Create the program code for a given ldpath.
+        # @param ldpath [String] ldpath to follow to get a value from a graph (documation: http://marmotta.apache.org/ldpath/language.html)
+        # @param prefixes [Hash] shortcut names for URI prefixes with key = part of predicate that is the same for all terms (e.g. { "madsrdf": "http://www.loc.gov/mads/rdf/v1#" })
+        # @param languages [Array<Symbol>] limit results to these languages and anything not tagged (applies to ldpaths with *LANG* marker)
+        # @return [String] the program code string used with Ldpath::Program.parse
+        def ldpath_program_code(ldpath:, prefixes: {}, languages: [])
+          program_code = ""
+          prefixes.each { |key, url| program_code << "@prefix #{key} : <#{url}> \;\n" }
+          property_explode(program_code, ldpath, languages)
+        end
+
+        # Evaluate an ldpath for a specific subject uri in the context of a graph and return the extracted values.
+        # @param program [Ldpath::Program] an executable program that will extract a value from a graph
+        # @param graph [RDF::Graph] the graph from which the values will be extracted
+        # @param subject_uri [RDF::URI] retrieved values will be limited to those with the subject uri
+        # @param limit_to_context [Boolean] if true, the evaluation process will not make any outside network calls.
+        #        It will limit results to those found in the context graph.
+        ## @return [Array<RDF::Literal>] the extracted values based on the ldpath
+        def ldpath_evaluate(program:, graph:, subject_uri:, limit_to_context: Qa.config.limit_ldpath_to_context?)
+          raise ArgumentError, "You must specify a program when calling ldpath_evaluate" if program.blank?
+          output = program.evaluate(subject_uri, context: graph, limit_to_context: limit_to_context)
+          property_implode(output)
+        rescue ParseError => e
+          Rails.logger.warn("WARNING: #{I18n.t('qa.linked_data.ldpath.evaluate_logger_error')} (cause: #{e.message}")
+          raise ParseError, I18n.t("qa.linked_data.ldpath.evaluate_error") + "... cause: #{e.message}"
+        end
+
+        private
+
+          # create program code with a property per language + untagged
+          def property_explode(program_code, ldpath, languages)
+            return program_code << "#{PROPERTY_NAME} = #{ldpath} \;\n" unless ldpath.index(LANGUAGE_PATTERN)
+            return program_code << "#{PROPERTY_NAME} = #{ldpath.gsub(LANGUAGE_PATTERN, '')} \;\n" unless languages.present?
+            languages.map { |language| program_code << "#{property_name_for(language)} = #{ldpath.gsub(LANGUAGE_PATTERN, "[@#{language}]")} \;\n" }
+            program_code << "#{PROPERTY_NAME} = #{ldpath.gsub(LANGUAGE_PATTERN, '[@none]')} \;\n"
+          end
+
+          # flatten all properties and turn into RDF::Literals with language tagging if appropriate
+          def property_implode(output)
+            return nil if output.blank?
+            output.each do |property_name, values|
+              output[property_name] = remap_string_values(property_name, values) if values.first.is_a? String
+            end
+            output.values.flatten.uniq
+          end
+
+          def property_name_for(language)
+            "#{language}_#{PROPERTY_NAME}"
+          end
+
+          def language_from(property_name)
+            return nil if property_name.casecmp?(PROPERTY_NAME)
+            property_name.chomp("_#{PROPERTY_NAME}")
+          end
 
-      # Evaluate an ldpath for a specific subject uri in the context of a graph and return the extracted values.
-      # @param program [Ldpath::Program] an executable program that will extract a value from a graph
-      # @param graph [RDF::Graph] the graph from which the values will be extracted
-      # @param subject_uri [RDF::URI] retrieved values will be limited to those with the subject uri
-      # @param limit_to_context [Boolean] if true, the evaluation process will not make any outside network calls.
-      #        It will limit results to those found in the context graph.
-      ## @return [Array<String>] the extracted values based on the ldpath
-      def self.ldpath_evaluate(program:, graph:, subject_uri:, limit_to_context: Qa.config.limit_ldpath_to_context?)
-        return VALUE_ON_ERROR if program.blank?
-        output = program.evaluate(subject_uri, context: graph, limit_to_context: limit_to_context)
-        output.present? ? output['property'].uniq : nil
-      rescue => e
-        Rails.logger.warn("WARNING: #{I18n.t('qa.linked_data.ldpath.evaluate_logger_error')} (cause: #{e.message}")
-        raise StandardError, I18n.t("qa.linked_data.ldpath.evaluate_error") + "... cause: #{e.message}"
+          def remap_string_values(property_name, values)
+            language = language_from(property_name)
+            values.map { |v| RDF::Literal.new(v, language: language) }
+          end
       end
     end
   end

app/services/qa/linked_data/mapper/graph_ldpath_mapper_service.rb

@@ -19,9 +19,10 @@ class GraphLdpathMapperService
         # @example ldpath map
         #   {
         #     uri: :subject_uri,
-        #     id: 'locid:lccn :: xsd::string',
+        #     id: 'locid:lccn',
         #     label: 'skos:prefLabel :: xsd::string',
         #     altlabel: 'skos:altLabel :: xsd::string',
+        #     sameas: 'skos:sameAs :: xsd::anyURI',
         #     sort: 'vivo:rank :: xsd::integer'
         #   }
         # @param subject_uri [RDF::URI] the subject within the graph for which the values are being extracted

spec/models/linked_data/config/context_property_map_spec.rb

@@ -277,9 +277,9 @@
     let(:expanded_id) { '123' }
 
     before do
-      allow(Ldpath::Program).to receive(:parse).with('property = madsrdf:identifiesRWO/madsrdf:birthDate/schema:label ;').and_return(basic_program)
-      allow(Ldpath::Program).to receive(:parse).with('property = skos:prefLabel ::xsd:string ;').and_return(expanded_label_program)
-      allow(Ldpath::Program).to receive(:parse).with('property = loc:lccn ::xsd:string ;').and_return(expanded_id_program)
+      allow(Ldpath::Program).to receive(:parse).with("property = madsrdf:identifiesRWO/madsrdf:birthDate/schema:label ;\n").and_return(basic_program)
+      allow(Ldpath::Program).to receive(:parse).with("property = skos:prefLabel ::xsd:string ;\n").and_return(expanded_label_program)
+      allow(Ldpath::Program).to receive(:parse).with("property = loc:lccn ::xsd:string ;\n").and_return(expanded_id_program)
       allow(basic_program).to receive(:evaluate).with(subject_uri, context: graph, limit_to_context: true).and_return('property' => [expanded_uri])
       allow(expanded_label_program).to receive(:evaluate).with(RDF::URI.new(subject_uri), context: graph, limit_to_context: true).and_return('property' => [expanded_label])
       allow(expanded_id_program).to receive(:evaluate).with(RDF::URI.new(subject_uri), context: graph, limit_to_context: true).and_return('property' => [expanded_id])

spec/services/linked_data/ldpath_service_spec.rb

@@ -17,10 +17,13 @@
     context 'when ldpath_program gets parse error' do
       let(:cause) { "undefined method `ascii_tree' for nil:NilClass" }
       let(:warning) { I18n.t('qa.linked_data.ldpath.parse_logger_error') }
-      let(:program_code) { "@prefix skos : <http://www.w3.org/2004/02/skos/core#> ;\nproperty = skos:prefLabel ::xsd:string ;" }
+      let(:program_code) { "BAD_PROGRAM ;" }
       let(:log_message) { "WARNING: #{warning}... cause: #{cause}\n   ldpath_program=\n#{program_code}" }
 
-      before { allow(Ldpath::Program).to receive(:parse).with(anything).and_raise(cause) }
+      before do
+        allow(described_class).to receive(:ldpath_program_code).with(anything).and_return(program_code)
+        allow(Ldpath::Program).to receive(:parse).with(anything).and_raise(cause)
+      end
 
       it 'logs error and returns PARSE ERROR as the value' do
         expect(Rails.logger).to receive(:warn).with(log_message)
@@ -29,32 +32,168 @@
     end
   end
 
+  describe '.ldpath_program_code' do
+    subject { described_class.ldpath_program_code(ldpath: ldpath, prefixes: prefixes, languages: languages) }
+
+    context 'for a ldpath without language pattern' do
+      let(:ldpath) { 'dcterms:identifier' }
+      let(:languages) { [:fr] }
+      let(:prefixes) { { "dcterms" => "http://purl.org/dc/terms/" } }
+      it 'generates the simple program code' do
+        expected_program = <<-PROGRAM
+@prefix dcterms : <http://purl.org/dc/terms/> \;
+property = dcterms:identifier \;
+PROGRAM
+        expect(subject).to eq expected_program
+      end
+    end
+
+    context 'for a ldpath with language pattern' do
+      let(:ldpath) { 'madsrdf:authoritativeLabel*LANG* ::xsd:string' }
+      let(:prefixes) { { "madsrdf" => "http://www.loc.gov/mads/rdf/v1#" } }
+      context 'and no languages specified' do
+        let(:languages) { nil }
+        it 'generates the simple program code' do
+          expected_program = <<-PROGRAM
+@prefix madsrdf : <http://www.loc.gov/mads/rdf/v1#> \;
+property = madsrdf:authoritativeLabel ::xsd:string \;
+PROGRAM
+          expect(subject).to eq expected_program
+        end
+      end
+
+      context 'and one language specified' do
+        let(:languages) { [:en] }
+        it 'generates a program with the language' do
+          expected_program = <<-PROGRAM
+@prefix madsrdf : <http://www.loc.gov/mads/rdf/v1#> \;
+en_property = madsrdf:authoritativeLabel[@en] ::xsd:string \;
+property = madsrdf:authoritativeLabel[@none] ::xsd:string \;
+PROGRAM
+          expect(subject).to eq expected_program
+        end
+      end
+
+      context 'and multiple languages specified' do
+        let(:languages) { [:fr, :de] }
+        it 'generates a program with languages' do
+          expected_program = <<-PROGRAM
+@prefix madsrdf : <http://www.loc.gov/mads/rdf/v1#> \;
+fr_property = madsrdf:authoritativeLabel[@fr] ::xsd:string \;
+de_property = madsrdf:authoritativeLabel[@de] ::xsd:string \;
+property = madsrdf:authoritativeLabel[@none] ::xsd:string \;
+PROGRAM
+          expect(subject).to eq expected_program
+        end
+      end
+    end
+  end
+
   describe '.ldpath_evaluate' do
     subject { described_class.ldpath_evaluate(program: program, graph: graph, subject_uri: subject_uri) }
 
     let(:program) { instance_double(Ldpath::Program) }
     let(:graph) { instance_double(RDF::Graph) }
     let(:subject_uri) { instance_double(RDF::URI) }
-    let(:values) { ['Expanded Label'] }
 
     before do
-      allow(Ldpath::Program).to receive(:parse).with('property = skos:prefLabel ::xsd:string ;').and_return(program)
-      allow(program).to receive(:evaluate).with(subject_uri, context: graph, limit_to_context: true).and_return('property' => values)
+      allow(Ldpath::Program).to receive(:parse).with(anything).and_return(program)
     end
-    it 'returns the extracted label' do
-      expect(subject).to match_array values
+
+    context 'when program does not contain languages' do
+      context 'and value is a string' do
+        let(:values) { ['value'] }
+        before do
+          allow(program).to receive(:evaluate)
+            .with(subject_uri, context: graph, limit_to_context: true)
+            .and_return('property' => values)
+        end
+        it 'returns the string values as is' do
+          expected_values = values.map { |v| RDF::Literal.new(v) }
+          expect(subject).to match_array expected_values
+        end
+      end
+
+      context 'and value is a URI' do
+        let(:values) { [RDF::URI.new('http://example.com/1'), RDF::URI.new('http://example.com/2')] }
+        before do
+          allow(program).to receive(:evaluate)
+            .with(subject_uri, context: graph, limit_to_context: true)
+            .and_return('property' => values)
+        end
+        it 'returns the URIs' do
+          expected_values = values
+          expect(subject).to match_array expected_values
+        end
+      end
+
+      context 'and value is numeric' do
+        let(:values) { [23, 14, 55] }
+        before do
+          allow(program).to receive(:evaluate)
+            .with(subject_uri, context: graph, limit_to_context: true)
+            .and_return('property' => values)
+        end
+        it 'returns the URIs' do
+          expected_values = values
+          expect(subject).to match_array expected_values
+        end
+      end
+    end
+
+    context 'when program has languages' do
+      context 'and one language specified' do
+        let(:en_values) { ['en_value'] }
+        let(:untagged_values) { ['untagged_value'] }
+        before do
+          allow(program).to receive(:evaluate)
+            .with(subject_uri, context: graph, limit_to_context: true)
+            .and_return('en_property' => en_values, 'property' => untagged_values)
+        end
+        it 'generates a program with the language' do
+          expected_values =
+            en_values.map { |v| RDF::Literal.new(v, language: :en) } +
+            untagged_values.map { |v| RDF::Literal.new(v) }
+          expect(subject).to match_array expected_values
+        end
+      end
+
+      context 'and multiple languages specified' do
+        let(:fr_values) { ['fr_value1', 'fr_value2', 'fr_value1'] }
+        let(:de_values) { ['de_value'] }
+        let(:untagged_values) { ['untagged_value'] }
+        before do
+          allow(program).to receive(:evaluate)
+            .with(subject_uri, context: graph, limit_to_context: true)
+            .and_return('fr_property' => fr_values, 'de_property' => de_values, 'property' => untagged_values)
+        end
+        it 'returns the extracted label' do
+          expected_values =
+            (fr_values.uniq.map { |v| RDF::Literal.new(v, language: :fr) } +
+             de_values.map { |v| RDF::Literal.new(v, language: :de) } +
+             untagged_values.map { |v| RDF::Literal.new(v) }).uniq
+          expect(subject).to match_array expected_values
+        end
+      end
     end
 
     context 'when ldpath_evaluate gets parse error' do
       let(:cause) { "unknown cause" }
       let(:warning) { I18n.t('qa.linked_data.ldpath.evaluate_logger_error') }
       let(:log_message) { "WARNING: #{warning} (cause: #{cause}" }
 
-      before { allow(program).to receive(:evaluate).with(subject_uri, context: graph, limit_to_context: true).and_raise(cause) }
+      before { allow(program).to receive(:evaluate).with(subject_uri, context: graph, limit_to_context: true).and_raise(ParseError, cause) }
 
       it 'logs error and returns PARSE ERROR as the value' do
         expect(Rails.logger).to receive(:warn).with(log_message)
-        expect { subject.values(graph, subject_uri) }.to raise_error StandardError, I18n.t('qa.linked_data.ldpath.evaluate_error') + "... cause: #{cause}"
+        expect { subject }.to raise_error ParseError, I18n.t('qa.linked_data.ldpath.evaluate_error') + "... cause: #{cause}"
+      end
+    end
+
+    context 'when program is empty' do
+      let(:program) { nil }
+      it 'returns empty array' do
+        expect { subject }.to raise_error ArgumentError, "You must specify a program when calling ldpath_evaluate"
       end
     end
   end