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 6

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 6

def load_from_solr
  @load_from_solr
end

#named_relationship_desc ⇒ Object

Returns the value of attribute named_relationship_desc.



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# File 'lib/active_fedora/semantic_node.rb', line 6

def named_relationship_desc
  @named_relationship_desc
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 6

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 9

def self.included(klass)
  klass.extend(ClassMethods)
end

Instance Method Details

#add_named_relationship(name, object) ⇒ Object

** EXPERIMENTAL **

Add an outbound relationship for given named relationship See ActiveFedora::SemanticNode::ClassMethods.has_relationship



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# File 'lib/active_fedora/semantic_node.rb', line 326

def add_named_relationship(name, object)
  if is_named_relationship?(name,true)
    if named_relationships_desc[:self][name].has_key?(:type)
      klass = class_from_name(named_relationships_desc[:self][name][:type])
      unless klass.nil?
        (assert_kind_of_model 'object', object, klass)
      end
    end
    #r = ActiveFedora::Relationship.new({:subject=>:self,:predicate=>outbound_named_relationship_predicates[name],:object=>object})
    #add_relationship(r)
    add_relationship(outbound_named_relationship_predicates[name],object)
  else
    false
  end
end

#add_relationship(relationship) ⇒ Object 



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

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 13

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

#assert_kind_of_model(name, object, model_class) ⇒ Object

** EXPERIMENTAL **

Throws an assertion error if kind_of_model? returns false for object and model_class

Parameters

name: Name of object (just label for output)
object: The object to test
model_class: The model class used to in kind_of_model? check on object



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# File 'lib/active_fedora/semantic_node.rb', line 360

def assert_kind_of_model(name, object, model_class)
  raise "Assertion failure: #{name}: #{object.pid} does not have model #{model_class}, it has model #{relationships[:self][:has_model]}" unless object.kind_of_model?(model_class)
end

#class_from_name(name) ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 391

def class_from_name(name)
  klass = name.to_s.split('::').inject(Kernel) {|scope, const_name| 
  scope.const_get(const_name)}
  (!klass.nil? && klass.is_a?(::Class)) ? klass : nil
end

#inbound_named_relationship_predicates ⇒ Object

** EXPERIMENTAL **

Return hash of inbound relationship names and predicate pairs



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# File 'lib/active_fedora/semantic_node.rb', line 216

def inbound_named_relationship_predicates
  named_relationship_predicates.has_key?(:inbound) ? named_relationship_predicates[:inbound] : {}
end

#inbound_relationship_names ⇒ Object

** EXPERIMENTAL **

Return array of relationship names for all named inbound relationships (coming from other objects’ RELS-EXT and Solr)



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# File 'lib/active_fedora/semantic_node.rb', line 255

def inbound_relationship_names
    named_relationships_desc.has_key?(:inbound) ? named_relationships_desc[:inbound].keys : []
end

#inbound_relationships(response_format = :uri) ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 90

def inbound_relationships(response_format=:uri)
  rel_values = {}
  inbound_named_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

#is_named_relationship?(name, outbound_only = true) ⇒ Boolean

** EXPERIMENTAL **

Returns true if the given relationship name is a named relationship

Parameters

name: Name of relationship
outbound_only:  If false checks inbound relationships as well (defaults to true)

Returns:

  • (Boolean) 


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# File 'lib/active_fedora/semantic_node.rb', line 280

def is_named_relationship?(name, outbound_only=true)
  if outbound_only
    outbound_relationship_names.include?(name)
  else
    (outbound_relationship_names.include?(name)||inbound_relationship_names.include?(name))
  end
end

#kind_of_model?(model_class) ⇒ Boolean

** EXPERIMENTAL **

Checks that this object is matches the model class passed in. It requires two steps to pass to return true

1. It has a hasModel relationship of the same model
2. kind_of? returns true for the model passed in

This method can most often be used to detect if an object from Fedora that was created with a different model was then used to populate this object.

Returns:

  • (Boolean) 


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# File 'lib/active_fedora/semantic_node.rb', line 372

def kind_of_model?(model_class)
   if self.kind_of?(model_class)
     #check has model and class match
     if relationships[:self].has_key?(:has_model)
       r = ActiveFedora::Relationship.new(:subject=>:self, :predicate=>:has_model, :object=>ActiveFedora::ContentModel.pid_from_ruby_class(self.class))
       if relationships[:self][:has_model].first.to_s.eql?(r.object.to_s)
         return true
       else
         raise "has_model relationship check failed for model #{model_class} raising exception, expected: '#{r.object.to_s}' actual: '#{relationships[:self][:has_model].to_s}'"
       end
     else
       raise "has_model relationship does not exist for model #{model_class} check raising exception"
     end
   else
    raise "kind_of? check failed for model #{model_class}, actual #{self.class} raising exception"
  end
  return false
end

#named_inbound_relationships ⇒ Object

** EXPERIMENTAL **

Return hash of named_relationships defined within other objects’ RELS-EXT It returns a hash of relationship name to arrays of objects. It requeries solr each time this method is called.



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# File 'lib/active_fedora/semantic_node.rb', line 192

def named_inbound_relationships
  rels = {}
  if named_relationships_desc.has_key?(:inbound)&&!named_relationships_desc[:inbound].empty?()
    inbound_rels = inbound_relationships
  
    if named_relationship_predicates.has_key?(:inbound)
      named_relationship_predicates[:inbound].each do |name, predicate|
        rels[name] = inbound_rels.has_key?(predicate) ? inbound_rels[predicate] : []
      end
    end
  end
  return rels
end

#named_outbound_relationships ⇒ Object

** EXPERIMENTAL **

Return hash of named_relationships defined within this object’s RELS-EXT It returns a hash of relationship name to arrays of objects



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# File 'lib/active_fedora/semantic_node.rb', line 270

def named_outbound_relationships
    named_relationships_desc.has_key?(:self) ? named_relationships[:self] : {}
end

#named_relationship(name) ⇒ Object

** EXPERIMENTAL **

Return array of objects for a given relationship name



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# File 'lib/active_fedora/semantic_node.rb', line 140

def named_relationship(name)
  rels = nil
  if inbound_relationship_names.include?(name)
    rels = named_relationships(false)[:inbound][name]
  elsif outbound_relationship_names.include?(name)
    rels = named_relationships[:self][name]
  end
  rels = [] if rels.nil?
  return rels
end

#named_relationship_predicates ⇒ Object

** EXPERIMENTAL **

Return hash of relationship names and predicate pairs



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# File 'lib/active_fedora/semantic_node.rb', line 223

def named_relationship_predicates
  @named_relationship_predicates ||= named_relationship_predicates_from_class
end

#named_relationship_predicates_from_class ⇒ Object

** EXPERIMENTAL **

Return hash of relationship names and predicate pairs from class



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# File 'lib/active_fedora/semantic_node.rb', line 230

def named_relationship_predicates_from_class
  rels = {}
  named_relationships_desc.each_pair do |subj, names|
    rels[subj] = {}
    names.each_pair do |name, args|
      rels[subj][name] = args[:predicate]
    end
  end
  return rels
end

#named_relationship_type(name) ⇒ Object

** EXPERIMENTAL **

Return the value of :type for the relationship for name passed in. It defaults to ActiveFedora::Base.



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# File 'lib/active_fedora/semantic_node.rb', line 312

def named_relationship_type(name)
  if is_named_relationship?(name,true)
    subject = outbound_relationship_names.include?(name)? :self : :inbound
    if named_relationships_desc[subject][name].has_key?(:type)
      return class_from_name(named_relationships_desc[subject][name][:type])
    end
  end
  return nil  
end

#named_relationships(outbound_only = true) ⇒ Object

** EXPERIMENTAL **

Gets the named relationships hash of subject=>name=>object_array It has an optional parameter of outbound_only that defaults true. If false it will include inbound relationships in the results. Also, it will only reload outbound relationships if the relationships hash has changed since the last time this method was called.



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# File 'lib/active_fedora/semantic_node.rb', line 158

def named_relationships(outbound_only=true)
  #make sure to update if relationships have been updated
  if @relationships_are_dirty == true
    @named_relationships = named_relationships_from_class()
    @relationships_are_dirty = false
  end
  
  #this will get called normally on first fetch if relationships are not dirty
  @named_relationships ||= named_relationships_from_class()
  outbound_only ? @named_relationships : @named_relationships.merge(:inbound=>named_inbound_relationships)      
end

#named_relationships_desc ⇒ Object

** EXPERIMENTAL **

Return hash that stores named relationship metadata defined by has_relationship calls

Example

For the following relationship

has_relationship "audio_records", :has_part, :type=>AudioRecord

Results in the following returned by named_relationships_desc

{:self=>{"audio_records"=>{:type=>AudioRecord, :singular=>nil, :predicate=>:has_part, :inbound=>false}}}



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# File 'lib/active_fedora/semantic_node.rb', line 297

def named_relationships_desc
  @named_relationships_desc ||= named_relationships_desc_from_class
end

#named_relationships_desc_from_class ⇒ Object

** EXPERIMENTAL **

Get class instance variable named_relationships_desc that holds has_relationship metadata



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# File 'lib/active_fedora/semantic_node.rb', line 304

def named_relationships_desc_from_class
  self.class.named_relationships_desc
end

#named_relationships_from_class ⇒ Object

** EXPERIMENTAL **

Gets named relationships from the class using the current relationships hash and relationship name,predicate pairs.



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# File 'lib/active_fedora/semantic_node.rb', line 174

def named_relationships_from_class()
  rels = {}
  named_relationship_predicates.each_pair do |subj, names|
    if relationships.has_key?(subj)
      rels[subj] = {}
      names.each_pair do |name, predicate|
        rels[subj][name] = (relationships[subj].has_key?(predicate) ? relationships[subj][predicate] : [])
      end
    end
  end
  return rels
end

#outbound_named_relationship_predicates ⇒ Object

** EXPERIMENTAL **

Return hash of outbound relationship names and predicate pairs



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# File 'lib/active_fedora/semantic_node.rb', line 209

def outbound_named_relationship_predicates
  named_relationship_predicates.has_key?(:self) ? named_relationship_predicates[:self] : {}
end

#outbound_relationship_names ⇒ Object

** EXPERIMENTAL **

Return array of relationship names for all named outbound relationships (coming from this object’s RELS-EXT)



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# File 'lib/active_fedora/semantic_node.rb', line 262

def outbound_relationship_names
    named_relationships_desc.has_key?(:self) ? named_relationships_desc[:self].keys : []
end

#outbound_relationships ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 112

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_named_relationship(subject, name, predicate, opts) ⇒ Object

** EXPERIMENTAL **

Internal method that adds relationship name and predicate pair to either an outbound (:self) or inbound (:inbound) relationship types. This method just calls the class method counterpart of this method.



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

def register_named_relationship(subject, name, predicate, opts)
  self.class.register_named_relationship(subject, name, predicate, opts)
end

#register_named_subject(subject) ⇒ Object

** EXPERIMENTAL **

Internal method that ensures a relationship subject such as :self and :inbound exist within the named_relationships_desc hash tracking named relationships metadata. This method just calls the class method counterpart of this method.



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# File 'lib/active_fedora/semantic_node.rb', line 48

def register_named_subject(subject)
  self.class.register_named_subject(subject)
end

#register_predicate(subject, predicate) ⇒ Object 



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# File 'lib/active_fedora/semantic_node.rb', line 36

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 30

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 24

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 83

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

#relationship_names ⇒ Object

** EXPERIMENTAL **

Return array all relationship names



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# File 'lib/active_fedora/semantic_node.rb', line 244

def relationship_names
  names = []
  named_relationships_desc.each_key do |subject|
        names = names.concat(named_relationships_desc[subject].keys)
    end
    names
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 121

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 126

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_named_relationship(name, object) ⇒ Object

** EXPERIMENTAL **

Remove an object from the named relationship



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# File 'lib/active_fedora/semantic_node.rb', line 345

def remove_named_relationship(name, object)
  if is_named_relationship?(name,true)
    remove_relationship(outbound_named_relationship_predicates[name],object)
  else
    return false
  end
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 63

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 401

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 71

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