Class: RDF::Changeset

Inherits:
Object
  • Object
show all
Defined in:
lib/changesets/rdf_changeset.rb

Constant Summary collapse

CONTENT_TYPE_TURTLE =

Media type for Changesets

"application/vnd.talis.changeset+turtle"
CONTENT_TYPE_XML = 
"application/vnd.talis.changeset+xml"
DEFAULT_REASON =

Default reason for applying the update to a graph

"Generated in changeset.rb"
DEFAULT_CREATOR =

Default name/label for the change agent

"changeset.rb"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(subject_of_change, change_reason = DEFAULT_REASON, creator_name = DEFAULT_CREATOR) ⇒ Changeset

Returns a new instance of Changeset.



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# File 'lib/changesets/rdf_changeset.rb', line 30

def initialize(subject_of_change, change_reason=DEFAULT_REASON, creator_name=DEFAULT_CREATOR)
  @resource = RDF::Node.new
  @subject_of_change = subject_of_change
  @statements = []
  @statements.concat [RDF::Statement.new(@resource, RDF.type, RDF::Talis::Changeset.ChangeSet),
   RDF::Statement.new(@resource, RDF::Talis::Changeset.changeReason, change_reason),
   RDF::Statement.new(@resource, RDF::Talis::Changeset.creatorName, creator_name),
   RDF::Statement.new(@resource, RDF::Talis::Changeset.createdDate, Time.now),
   RDF::Statement.new(@resource, RDF::Talis::Changeset.subjectOfChange, subject_of_change)]
   if block_given?
     yield self
   end
end

Instance Attribute Details

#statements ⇒ Object (readonly)

Returns the value of attribute statements.



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# File 'lib/changesets/rdf_changeset.rb', line 28

def statements
  @statements
end

#subject_of_change ⇒ Object (readonly)

Returns the value of attribute subject_of_change.



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# File 'lib/changesets/rdf_changeset.rb', line 28

def subject_of_change
  @subject_of_change
end

Class Method Details

.remove_properties(subject, predicate, graph, change_reason = DEFAULT_REASON, creator_name = DEFAULT_CREATOR) ⇒ Object

Remove all statements with a specific predicate for a specific resource



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# File 'lib/changesets/rdf_changeset.rb', line 105

def Changeset.remove_properties(subject, predicate, graph, change_reason=DEFAULT_REASON, creator_name=DEFAULT_CREATOR)
  cs = Changeset.new(subject, change_reason, creator_name) do |cs|
    graph.query( [subject, predicate, nil] ).each do |statement|
      cs.remove_statements( statement )
    end              
  end                  
  cs
end

.remove_property(subject, predicate, value, change_reason = DEFAULT_REASON, creator_name = DEFAULT_CREATOR) ⇒ Object

Remove a specific single property for a subject



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# File 'lib/changesets/rdf_changeset.rb', line 92

def Changeset.remove_property(subject, predicate, value, change_reason=DEFAULT_REASON, creator_name=DEFAULT_CREATOR)
  return Changeset.remove_statement( RDF::Statement.new( subject, predicate, value ) )
end

.remove_statement(statement, change_reason = DEFAULT_REASON, creator_name = DEFAULT_CREATOR) ⇒ Object

Remove a statement



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# File 'lib/changesets/rdf_changeset.rb', line 97

def Changeset.remove_statement( statement, change_reason=DEFAULT_REASON, creator_name=DEFAULT_CREATOR)
  cs = Changeset.new(statement.subject, change_reason, creator_name) do |cs|
    cs.remove_statements( statement )
  end
  cs
end

.remove_subject(subject, graph, change_reason = DEFAULT_REASON, creator_name = DEFAULT_CREATOR) ⇒ Object

Remove all statements where the indicated resource is the subject



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# File 'lib/changesets/rdf_changeset.rb', line 115

def Changeset.remove_subject(subject, graph, change_reason=DEFAULT_REASON, creator_name=DEFAULT_CREATOR)
  cs = Changeset.new(subject, change_reason, creator_name) do |cs|
    graph.query( [subject, nil, nil] ).each do |statement|
      cs.remove_statements( statement )
    end              
  end                  
  cs      
end

.update(subject, new, old, change_reason = DEFAULT_REASON, creator_name = DEFAULT_CREATOR) ⇒ Object

Apply an update by removing all statements for the indicated subject from the old graph, replacing it with statements in the new graph



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# File 'lib/changesets/rdf_changeset.rb', line 126

def Changeset.update(subject, new, old, change_reason=DEFAULT_REASON, creator_name=DEFAULT_CREATOR)
  cs = Changeset.new(subject, change_reason, creator_name) do |cs|
    old.query( [subject, nil, nil] ).each do |statement|
      cs.remove_statements( statement )
    end        
    new.query( [subject, nil, nil] ).each do |statement|
      cs.add_statements( statement )
    end
  end      
  cs
end

.update_property(subject, predicate, old_value, new_value, change_reason = DEFAULT_REASON, creator_name = DEFAULT_CREATOR) ⇒ Object

Update a predicate from one value to another Will only remove the specified old value, other values for predicate will remain unchanged



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# File 'lib/changesets/rdf_changeset.rb', line 83

def Changeset.update_property(subject, predicate, old_value, new_value, change_reason=DEFAULT_REASON, creator_name=DEFAULT_CREATOR)
  cs = Changeset.new(subject, change_reason, creator_name) do |cs|
    cs.remove_statements( RDF::Statement.new( subject, predicate, old_value ) )
    cs.add_statements( RDF::Statement.new( subject, predicate, new_value ) )        
  end
  cs
end

Instance Method Details

#add_statements(stmts) ⇒ Object

Add these statements to the graph



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# File 'lib/changesets/rdf_changeset.rb', line 54

def add_statements(stmts)
  stmts = [stmts] if stmts.is_a?(RDF::Statement)
  stmts.each do |stmt|
    next unless stmt
    raise ArgumentError unless stmt.subject == @subject_of_change        
    @statements.concat changeset_statement(stmt, :addition)
  end
end

#changeset_statement(stmt, action) ⇒ Object 



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# File 'lib/changesets/rdf_changeset.rb', line 63

def changeset_statement(stmt, action)
  s = RDF::Node.new
  [RDF::Statement.new(@resource, RDF::Talis::Changeset.send(action), s),
    RDF::Statement.new(s, RDF.type, RDF.to_rdf+"Statement"),
    RDF::Statement.new(s, RDF.subject, stmt.subject),
    RDF::Statement.new(s, RDF.predicate, stmt.predicate),
    RDF::Statement.new(s, RDF.object, stmt.object)]
end

#remove_statements(stmts) ⇒ Object

Remove these statements from the graph



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# File 'lib/changesets/rdf_changeset.rb', line 45

def remove_statements(stmts)
  stmts = [stmts] if stmts.is_a?(RDF::Statement)
  stmts.each do |stmt|
    raise ArgumentError unless stmt.subject == @subject_of_change        
    @statements.concat changeset_statement(stmt, :removal)
  end
end

#to_graph ⇒ Object

Convert into an RDF::Graph object



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# File 'lib/changesets/rdf_changeset.rb', line 73

def to_graph
  graph = RDF::Graph.new()
  @statements.each do |s|
    graph << s
  end
  graph
end