Module: ActiveFedora::SemanticNode

Includes:
MediaShelfClassLevelInheritableAttributes
Included in:
Base, RelsExtDatastream
Defined in:
lib/active_fedora/semantic_node.rb

Defined Under Namespace

Modules: ClassMethods

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#internal_uri ⇒ Object

Returns the value of attribute internal_uri.



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# File 'lib/active_fedora/semantic_node.rb', line 9

def internal_uri
  @internal_uri
end

#load_from_solr ⇒ Object

Returns the value of attribute load_from_solr.



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# File 'lib/active_fedora/semantic_node.rb', line 9

def load_from_solr
  @load_from_solr
end

#relationships_are_dirty ⇒ Object

Returns the value of attribute relationships_are_dirty.



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# File 'lib/active_fedora/semantic_node.rb', line 9

def relationships_are_dirty
  @relationships_are_dirty
end

Class Method Details

.included(klass) ⇒ Object 



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

def self.included(klass)
  klass.extend(ClassMethods)
  klass.send(:include, ActiveFedora::RelationshipsHelper)
end

Instance Method Details

#add_relationship(relationship) ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 21

def add_relationship(relationship)
  # Only accept ActiveFedora::Relationships as input arguments
  assert_kind_of 'relationship',  relationship, ActiveFedora::Relationship
  self.relationships_are_dirty = true
  register_triple(relationship.subject, relationship.predicate, relationship.object)
end

#assert_kind_of(n, o, t) ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 17

def assert_kind_of(n, o,t)
  raise "Assertion failure: #{n}: #{o} is not of type #{t}" unless o.kind_of?(t)
end

#inbound_relationships(response_format = :uri) ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 77

def inbound_relationships(response_format=:uri)
  rel_values = {}
  inbound_relationship_predicates.each_pair do |name,predicate|
    objects = self.send("#{name}",{:response_format=>response_format})
    items = []
    objects.each do |object|
      if (response_format == :uri)    
        #create a Relationship object so that it generates the appropriate uri
        #inbound relationships are always object properties
        r = ActiveFedora::Relationship.new(:subject=>:self, :predicate=>predicate, :object=>object)
        items.push(r.object)
      else
        items.push(object)
      end
    end
    unless items.empty?
      rel_values.merge!({predicate=>items})
    end
  end
  return rel_values  
end

#outbound_relationships ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 99

def outbound_relationships()
  if !internal_uri.nil? && !relationships[internal_uri].nil?
    return relationships[:self].merge(relationships[internal_uri]) 
  else
    return relationships[:self]
  end
end

#register_predicate(subject, predicate) ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 40

def register_predicate(subject, predicate)
  register_subject(subject)
  if !relationships[subject].has_key?(predicate) 
    relationships[subject][predicate] = []
  end
end

#register_subject(subject) ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 34

def register_subject(subject)
  if !relationships.has_key?(subject) 
      relationships[subject] = {} 
  end
end

#register_triple(subject, predicate, object) ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 28

def register_triple(subject, predicate, object)
  register_subject(subject)
  register_predicate(subject, predicate)
  relationships[subject][predicate] << object
end

#relationship_exists?(subject, predicate, object) ⇒ Boolean

** EXPERIMENTAL **

Returns true if a relationship exists for the given subject, predicate, and object triple

Returns:

  • (Boolean) 


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# File 'lib/active_fedora/semantic_node.rb', line 70

def relationship_exists?(subject, predicate, object)
  outbound_only = (subject != :inbound)
  #cache the call in case it is retrieving inbound as well, don't want to hit solr too many times
  cached_relationships = relationships(outbound_only)
  cached_relationships.has_key?(subject)&&cached_relationships[subject].has_key?(predicate)&&cached_relationships[subject][predicate].include?(object)
end

#relationships(outbound_only = true) ⇒ Object

If outbound_only is false, inbound relationships will be included.



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# File 'lib/active_fedora/semantic_node.rb', line 108

def relationships(outbound_only=true)
  @relationships ||= relationships_from_class
  outbound_only ? @relationships : @relationships.merge(:inbound=>inbound_relationships)
end

#relationships_from_class ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 113

def relationships_from_class
  rels = {}
  self.class.relationships.each_pair do |subj, pred|
    rels[subj] = {}
    pred.each_key do |pred_key|
      rels[subj][pred_key] = []
    end
  end
  return rels
end

#remove_relationship(relationship) ⇒ Object

** EXPERIMENTAL **

Remove the given ActiveFedora::Relationship from this object



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# File 'lib/active_fedora/semantic_node.rb', line 50

def remove_relationship(relationship)
  @relationships_are_dirty = true
  unregister_triple(relationship.subject, relationship.predicate, relationship.object)
end

#to_rels_ext(pid, relationships = self.relationships) ⇒ Object

Creates a RELS-EXT datastream for insertion into a Fedora Object Note: This method is implemented on SemanticNode instead of RelsExtDatastream because SemanticNode contains the relationships array

Parameters:

  • pid (String)
  • relationships (Hash) (defaults to: self.relationships) —

    (optional) @default self.relationships



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# File 'lib/active_fedora/semantic_node.rb', line 128

def to_rels_ext(pid, relationships=self.relationships)
  starter_xml = <<-EOL
  <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
    <rdf:Description rdf:about="info:fedora/#{pid}">
    </rdf:Description>
  </rdf:RDF>
  EOL
  xml = REXML::Document.new(starter_xml)

  # Iterate through the hash of predicates, adding an element to the RELS-EXT for each "object" in the predicate's corresponding array.
  # puts ""
  # puts "Iterating through a(n) #{self.class}"
  # puts "=> whose relationships are #{self.relationships.inspect}"
  # puts "=> and whose outbound relationships are #{self.outbound_relationships.inspect}"
  self.outbound_relationships.each do |predicate, targets_array|
    targets_array.each do |target|
      xmlns=String.new
      case predicate
      when :has_model, "hasModel", :hasModel
        xmlns="info:fedora/fedora-system:def/model#"
        begin
          rel_predicate = self.class.predicate_lookup(predicate,xmlns)
        rescue UnregisteredPredicateError
          xmlns = nil
          rel_predicate = nil
        end
      else
        xmlns="info:fedora/fedora-system:def/relations-external#"
        begin
          rel_predicate = self.class.predicate_lookup(predicate,xmlns)
        rescue UnregisteredPredicateError
          xmlns = nil
          rel_predicate = nil
        end
      end
      
      unless xmlns && rel_predicate
        rel_predicate, xmlns = self.class.find_predicate(predicate)
      end
      # puts ". #{predicate} #{target} #{xmlns}"
      literal = URI.parse(target).scheme.nil?
      if literal
        xml.root.elements["rdf:Description"].add_element(rel_predicate, {"xmlns" => "#{xmlns}"}).add_text(target)
      else
        xml.root.elements["rdf:Description"].add_element(rel_predicate, {"xmlns" => "#{xmlns}", "rdf:resource"=>target})
      end
    end
  end
  xml.to_s
end

#unregister_triple(subject, predicate, object) ⇒ Object

** EXPERIMENTAL **

Remove the subject, predicate, and object triple from the relationships hash



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# File 'lib/active_fedora/semantic_node.rb', line 58

def unregister_triple(subject, predicate, object)
  if relationship_exists?(subject, predicate, object)
    relationships[subject][predicate].delete_if {|curObj| curObj == object}
    relationships[subject].delete(predicate) if relationships[subject][predicate].nil? || relationships[subject][predicate].empty? 
  else
    return false
  end     
end