Class: DirectAccess

Inherits:
Object
  • Object
show all
Defined in:
lib/active_rdf/directaccess/direct_access.rb

Overview

Direct access for Redland adapter

Syntax “<http://.…..>” = Resource “abc” = Literal “_:” = Blank Node “_:123” = Blank Node with id

Class Method Summary collapse

Class Method Details

.find_all_by_subject_and_predicate(s, p) ⇒ Object

Find all triple by subject and predicate The return value is a PropertyList



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# File 'lib/active_rdf/directaccess/direct_access.rb', line 36

def self.find_all_by_subject_and_predicate(s,p)
  # verify input
  if s.nil? || p.nil?
    raise ActiveRdfError, "subject and predicate can't be nil"
  end
  
  # execute query
  query_result = self.sparql_query("SELECT ?o WHERE {#{s} #{p} ?o}")
  
  # return propertyList
  return PropertyList.new(p, query_result, s)
end

.sparql_query(query, result_format = :array) ⇒ Object

Execute a SPARQL query. The second parameter specify the result format (:json, :xml, :array) (optional)

The return default value is an Array. If you specify :xml or :json in result_format, the return value is a String that contain the request format.

Example: query(“SELECT ?p ?o WHERE href="http://activerdf.org/test/eyal">activerdf.org/test/eyal> ?p ?o”, :json)



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# File 'lib/active_rdf/directaccess/direct_access.rb', line 19

def self.sparql_query(query, result_format=:array)
  # verify input
  if query.nil?
    raise ActiveRdfError, "cannot execute empty query"
  end
  
  # verify class type
  if query.class != String
    raise ActiveRdfError, "query must be String."
  end
  
  # execute query
  FederationManager.query(query, {:result_format => result_format})
end