Class: ActiveFedora::RDFDatastream

Inherits:
Datastream
  • Object
show all
Includes:
RdfNode, Solrizer::Common
Defined in:
lib/active_fedora/rdf_datastream.rb

Direct Known Subclasses

NtriplesRDFDatastream, RdfxmlRDFDatastream

Instance Attribute Summary

Attributes inherited from Datastream

#digital_object, #last_modified

Class Method Summary collapse

Instance Method Summary collapse

Methods included from RdfNode

#==, #append, #attributes=, #config_for_term_or_uri, #delete_predicate, #destroy, #find_predicate, #get_values, #insert_child, #mark_for_destruction, #marked_for_destruction?, #new_record=, #new_record?, #query, rdf_registry, #rdf_subject, #reset_child_cache!, #reset_rdf_subject!, #set_value, #target_class

Methods inherited from Datastream

#create, #initialize, #inspect, #label, #profile_from_hash, #realLabel, #save, #serialize!, #solrize_profile, #to_param, #validate_content_present

Constructor Details

This class inherits a constructor from ActiveFedora::Datastream

Class Method Details

.rdf_subject {|ds| ... } ⇒ Object

Register a ruby block that evaluates to the subject of the graph By default, the block returns the current object’s pid This should override the method in RdfObject, which just creates a b-node by default

Yields:

  • (ds) —

    ‘ds’ is the datastream instance



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# File 'lib/active_fedora/rdf_datastream.rb', line 20

def rdf_subject &block
  if block_given?
     return @subject_block = block
  end

  @subject_block ||= lambda { |ds| RDF::URI.new("info:fedora/#{ds.pid}") }
end

Instance Method Details

#content ⇒ Object

Overriding so that one can call ds.content on an unsaved datastream and they will see the serialized format



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

def content
  serialize
end

#content=(content) ⇒ Object 



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# File 'lib/active_fedora/rdf_datastream.rb', line 44

def content=(content)
  reset_child_cache!
  @graph = deserialize(content)
end

#content_changed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_fedora/rdf_datastream.rb', line 49

def content_changed?
  # we haven't touched the graph, so it isn't changed (avoid a force load)
  return false unless instance_variable_defined? :@graph
  @content = serialize
  super
end

#deserialize(data = nil) ⇒ Object

Populate a RDFDatastream object based on the “datastream” content Assumes that the datastream contains RDF content

Parameters:

  • data (String) (defaults to: nil) —

    the “rdf” node



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

def deserialize(data = nil)
  repository = RDF::Repository.new
  return repository if new? and data.nil?

  data ||= datastream_content
  data.force_encoding('utf-8')
  RDF::Reader.for(serialization_format).new(data) do |reader|
    reader.each_statement do |statement|
      repository << statement
    end
  end

  repository
end

#graph ⇒ Object 



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# File 'lib/active_fedora/rdf_datastream.rb', line 88

def graph
  @graph ||= begin
    deserialize
  end      
end

#metadata? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_fedora/rdf_datastream.rb', line 29

def metadata?
  true
end

#prefix(name) ⇒ Object 



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# File 'lib/active_fedora/rdf_datastream.rb', line 33

def prefix(name)
  name = name.to_s unless name.is_a? String
  pre = dsid.underscore
  return "#{pre}__#{name}".to_sym
end

#serialization_format ⇒ Object 



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# File 'lib/active_fedora/rdf_datastream.rb', line 94

def serialization_format
  raise "you must override the `serialization_format' method in a subclass"
end

#serialize ⇒ Object

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



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# File 'lib/active_fedora/rdf_datastream.rb', line 100

def serialize
  update_subjects_to_use_a_real_pid!

  RDF::Writer.for(serialization_format).dump(graph)
end

#to_solr(solr_doc = Hash.new) ⇒ Object

:nodoc:



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

def to_solr(solr_doc = Hash.new) # :nodoc:
  fields.each do |field_key, field_info|
    values = get_values(rdf_subject, field_key)
    if values
      Array(values).each do |val|    
        val = val.to_s if val.kind_of? RDF::URI
        self.class.create_and_insert_terms(prefix(field_key), val, field_info[:behaviors], solr_doc)
      end
    end
  end
  solr_doc
end