Class: ActiveFedora::RelationshipGraph

Inherits:
Object
  • Object
show all
Defined in:
lib/active_fedora/relationship_graph.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ RelationshipGraph

Returns a new instance of RelationshipGraph.



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# File 'lib/active_fedora/relationship_graph.rb', line 7

def initialize 
  self.dirty = false
  self.relationships = Hash.new { |h, k| h[k] = [] }
end

Instance Attribute Details

#dirty ⇒ Object

Returns the value of attribute dirty.



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# File 'lib/active_fedora/relationship_graph.rb', line 4

def dirty
  @dirty
end

#relationships ⇒ Object

Returns the value of attribute relationships.



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# File 'lib/active_fedora/relationship_graph.rb', line 4

def relationships
  @relationships
end

Instance Method Details

#[](predicate) ⇒ Object 



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# File 'lib/active_fedora/relationship_graph.rb', line 51

def [](predicate)
  uri = uri_predicate(predicate)
  relationships[uri]
end

#add(predicate, object, literal = false) ⇒ Object 



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# File 'lib/active_fedora/relationship_graph.rb', line 16

def add(predicate, object, literal=false)
  uri = uri_predicate(predicate)
  unless has_predicate? uri
    relationships[uri] = []
  end
  object = RDF::Literal.new(object) if literal
  unless relationships[uri].include?(object)
    @dirty = true
    relationships[uri] << object
  end
end

#build_statement(uri, predicate, target) ⇒ Object

Create an RDF statement

Parameters:

  • uri —

    a string represending the subject

  • predicate (Symbol, URI) —

    a predicate

  • target —

    an object to store



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# File 'lib/active_fedora/relationship_graph.rb', line 73

def build_statement(uri, predicate, target)
  raise "Not allowed anymore" if uri == :self
  target = target.internal_uri if target.respond_to? :internal_uri
  subject =  RDF::URI.new(uri)  #TODO cache
  if target.is_a? RDF::Literal or target.is_a? RDF::Resource
    object = target
  else
    begin
      target_uri = (target.is_a? URI) ? target : URI.parse(target)
      if target_uri.scheme.nil?
        raise ArgumentError, "Invalid target \"#{target}\". Must have namespace."
      end
      if target_uri.to_s =~ /\A[\w\-]+:[\w\-]+\Z/
        raise ArgumentError, "Invalid target \"#{target}\". Target should be a complete URI, and not a pid."
      end
    rescue URI::InvalidURIError
      raise ArgumentError, "Invalid target \"#{target}\". Target must be specified as a literal, or be a valid URI."
    end
    object = RDF::URI.new(target)
  end
  RDF::Statement.new(subject, uri_predicate(predicate), object)

end

#delete(predicate, object = nil) ⇒ Object

Remove the statement matching the predicate and object

Parameters:

  • predicate (Symbol, URI) —

    the predicate to delete

  • object (defaults to: nil) —

    the object to delete, if nil, all statements with this predicate are deleted.



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# File 'lib/active_fedora/relationship_graph.rb', line 31

def delete(predicate, object = nil)
  uri = uri_predicate(predicate)
  return unless has_predicate? uri 
  if object.nil?
    @dirty = true
    relationships.delete(uri)
    return
  end
  if relationships[uri].include?(object)
    @dirty = true
    relationships[uri].delete(object)
  end
  if object.respond_to?(:internal_uri) && relationships[uri].include?(object.internal_uri)
    @dirty = true
    relationships[uri].delete(object.internal_uri)
  elsif object.is_a? String 
    relationships[uri].delete_if{|obj| obj.respond_to?(:internal_uri) && obj.internal_uri == object}
  end
end

#has_predicate?(predicate) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_fedora/relationship_graph.rb', line 12

def has_predicate?(predicate)
  relationships.has_key? uri_predicate(predicate)
end

#to_graph(subject_uri) ⇒ Object 



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# File 'lib/active_fedora/relationship_graph.rb', line 56

def to_graph(subject_uri)
  # need to destroy relationships and rewrite it.
  subject =  RDF::URI.new(subject_uri)
  graph = RDF::Graph.new
  relationships.each do |predicate, values|
    values.each do |object|
      graph.insert build_statement(subject,  predicate, object)
    end
  end

  graph
end

#uri_predicate(predicate) ⇒ Object 



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# File 'lib/active_fedora/relationship_graph.rb', line 97

def uri_predicate(predicate)
  return predicate if predicate.kind_of? RDF::URI
  ActiveFedora::Predicates.find_graph_predicate(predicate)
end