Class: Qa::LinkedData::GraphService

Inherits:
Object
  • Object
show all
Defined in:
app/services/qa/linked_data/graph_service.rb

Class Method Summary collapse

Class Method Details

.deep_copy(graph:) ⇒ Object 



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# File 'app/services/qa/linked_data/graph_service.rb', line 57

def deep_copy(graph:)
  new_graph = RDF::Graph.new
  graph.statements.each do |st|
    new_graph.insert(st.dup)
  end
  new_graph
end

.filter(graph:, language: nil, remove_blanknode_subjects: false) ⇒ RDF::Graph

Create a new graph with statements filtered out



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# File 'app/services/qa/linked_data/graph_service.rb', line 21

def filter(graph:, language: nil, remove_blanknode_subjects: false)
  return graph unless graph.present?
  return graph unless language.present? || remove_blanknode_subjects
  filtered_graph = deep_copy(graph: graph)
  filtered_graph.statements.each do |st|
    filtered_graph.delete(st) if filter_out_blanknode(remove_blanknode_subjects, st.subject) || filter_out_language(graph, language, st)
  end
  filtered_graph
end

.load_graph(url:) ⇒ RDF::Graph

Retrieve linked data from specified url



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# File 'app/services/qa/linked_data/graph_service.rb', line 9

def load_graph(url:)
  RDF::Graph.load(url)
rescue IOError => e
  process_error(e, url)
end

.object_values(graph:, subject:, predicate:) ⇒ Array

Get object values from the graph that have the subject-predicate.



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# File 'app/services/qa/linked_data/graph_service.rb', line 36

def object_values(graph:, subject:, predicate:)
  values = []
  graph.query([subject, predicate, :object]) do |statement|
    values << statement.object
  end
  values
end

.subjects_for_object_value(graph:, predicate:, object_value:) ⇒ Array

Get subjects that have the object value for the predicate in the graph.



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# File 'app/services/qa/linked_data/graph_service.rb', line 49

def subjects_for_object_value(graph:, predicate:, object_value:)
  subjects = []
  graph.query([:subject, predicate, object_value]) do |statement|
    subjects << statement.subject
  end
  subjects
end