How to recursively expand blank nodes in SPARQL construct query?

Question

There is probably an easy to answer to this, but I can\'t even figure out how to formulate the Google query to find it.

I\'m writing SPARQL construct queries against a d

Answer 1

With regard to working with the ruby RDF.rb library, which allows SPARQL queries with significant convenience methods on RDF::Graph objects, the following should expand blank nodes.

rdf_type = RDF::SCHEMA.Person # for example
rdf.query([nil, RDF.type, rdf_type]).each_subject do |subject|
  g = RDF::Graph.new
  rdf.query([subject, nil, nil]) do |s,p,o|
    g << [s,p,o]
    g << rdf_expand_blank_nodes(o) if o.node?
  end
end

def rdf_expand_blank_nodes(object)
  g = RDF::Graph.new
  if object.node?
    rdf.query([object, nil, nil]) do |s,p,o|
      g << [s,p,o]
      g << rdf_expand_blank_nodes(o) if o.node?
    end
  end
  g
end