rdflib 0.2.0

A pure Dart package for working with RDF (resource description framework).

RDFLib

A pure Dart package for working with RDF (resource description framework).

Features

• Create triple instances (with data types)
• Create a graph to store triples without duplicates
• Find triples based on criteria
• Export graph to turtle ttl format (default)
  • Export to encrypted turtle ttl file with AES encryption
• Bind long namespace with customized shortened name for readability
• Include reserved vocabulary of OWL 2
• Parse local turtle ttl file and store triples in the graph in memory
  • Parse encrypted turtle ttl file which is encrypted using AES
  • Parse long text string stored in memory

Getting started

Refer to the code example below, or go to /example to find out more!

For testing the rdflib package

# create a dart project for testing
dart create test_rdflib
cd test_rdflib
# install rdflib as the dependency with dart pub add
dart pub add rdflib
# copy the following code to /bin/test_rdflib.dart
# run the file with dart
dart run

Usage

Head over to our GitHub repo to check out more examples!

1. General usage

The following code snippet shows how to:

1. Create a Graph instance;
2. Create and store triples with different data types;
3. Find entities based on customized criteria;
4. Bind shorted string to long namespace;
5. Export graph data to turtle file;

import 'dart:io';
import 'package:rdflib/rdflib.dart';

main() async {
  /// the following example is modified from <https://rdflib.readthedocs.io/en/stable/gettingstarted.html#a-more-extensive-example>
  Graph g = Graph();

  URIRef example = URIRef.fullUri('http://example.org');

  // subject and predicate should be a valid URIRef instance
  URIRef donna = example.slash('donna');

  g.add(Triple(sub: donna, pre: RDF.type, obj: FOAF.Person));

  // add duplicated record
  g.add(Triple(sub: donna, pre: RDF.type, obj: FOAF.Person));
  g.add(Triple(sub: donna, pre: FOAF.nick, obj: Literal('donna', lang: 'en')));
  g.add(Triple(sub: donna, pre: FOAF.name, obj: Literal('Donna Fales')));

  // add duplicated record
  g.add(Triple(sub: donna, pre: FOAF.name, obj: Literal('Donna Fales')));
  g.add(Triple(
      sub: donna,
      pre: FOAF.mbox,
      obj: URIRef.fullUri('mailto:[e-mail]')));

  // add another in the graph
  URIRef ed = example.slash('edward');
  g.add(Triple(sub: ed, pre: RDF.type, obj: FOAF.Person));
  g.add(Triple(
      sub: ed, pre: FOAF.nick, obj: Literal('ed', datatype: XSD.string)));
  g.add(Triple(sub: ed, pre: FOAF.name, obj: 'Edward Scissorhands'));
  g.add(Triple(
      sub: ed,
      pre: FOAF.mbox,
      obj: Literal('[e-mail]', datatype: XSD.anyURI)));

  // TEST triples should print correctly
  print('-' * 30);
  for (Triple t in g.triples) {
    // duplicated records will not be added and printed out
    print(t);
  }

  print('-' * 30);

  // TEST correct subjects/objects should print out
  for (URIRef s in g.subjects(RDF.type, FOAF.Person)) {
    for (var o in g.objects(s, FOAF.mbox)) {
      // should print out URIRef(mailto:[e-mail]) and
      // Literal([e-mail], datatype: URIRef(http://www.w3.org/2001/XMLSchema#anyURI))
      print(o);
    }
  }

  // bind 'foaf' to FOAF for easy readout
  g.bind('foaf', FOAF(ns: FOAF.foaf));

  /// uncomment the following line to test binding a customized namespace
  /// g.bind('example', Namespace(ns: 'http://example.org/'));

  // export graph to turtle format, create directory if it doesn't exist
  String currentPath = Directory.current.path;
  String examplePath = '$currentPath/example';
  if (!await Directory(examplePath).exists()) {
    await Directory(examplePath).create(recursive: true);
  }
  g.serialize(format: 'ttl', dest: '$examplePath/ex1.ttl');
  // can also export to an encrypted file (will add .enc before .ttl in file name)
  g.serialize(
      format: 'ttl',
      dest: '$examplePath/ex1.ttl',
      encrypt: 'AES',
      passphrase: 'helloworld!');
}

2. SOLID Health Ontology Example

import '../lib/rdflib.dart';

main() {
  Graph g = Graph();

  Namespace shData = Namespace(ns: 'http://silo.net.au/data/SOLID-Health#');
  Namespace shOnto =
  Namespace(ns: 'http://sii.cecs.anu.edu.au/onto/SOLID-Health#');

  URIRef newAssessTab = shData.withAttr('AssessmentTab-p43623-20220727T120913');
  g.addNamedIndividual(newAssessTab);

  // Literal string
  g.add(Triple(
      sub: newAssessTab, pre: RDF.type, obj: shOnto.withAttr('AssessmentTab')));

  // Literal string
  g.add(Triple(
      sub: newAssessTab,
      pre: shOnto.withAttr('asthmaControl'),
      obj: Literal('Poor Control')));

  // Literal integer
  g.add(Triple(
      sub: newAssessTab,
      pre: shOnto.withAttr('diastolicBloodPressure'),
      obj: Literal('75')));

  // Literal float/double
  g.add(Triple(
      sub: newAssessTab,
      pre: shOnto.withAttr('systolicBloodPressure'),
      obj: Literal('125.0')));

  URIRef newSeeAndDoTab = shData.withAttr('SeeAndDoTab-p43623-20220727T120913');
  URIRef newSeeAndDoOption =
  shData.withAttr('SeeAndDoOption-p43623-20220727T120913-fitnessDrive');

  g.addNamedIndividual(newSeeAndDoTab);
  g.addNamedIndividual(newSeeAndDoOption);
  // link two triple individuals
  g.addObjectProperty(
      newSeeAndDoTab, shOnto.withAttr('hasSeeAndDoOption'), newSeeAndDoOption);

  /// binding for readability
  g.bind('sh-data', shData);
  g.bind('sh-onto', shOnto);

  g.serialize(dest: 'example/ex2.ttl');
}

3. Parsing local turtle file

import 'package:rdflib/rdflib.dart';

main() async {
  String filePath = 'example/ex1.ttl';
  // create a graph to read turtle file and store info
  Graph g = Graph();
  // wait for it to complete parsing
  await g.parse(filePath);
  // full format of triples (will use shorthand in serialization/export)
  for (Triple t in g.triples) {
    print(t);
  }
  // export it to a new file (should be equivalent to the original one)
  g.serialize(format: 'ttl', dest: 'example/ex3.ttl');
}

3.1 Parsing encrypted local turtle file

import 'package:rdflib/rdflib.dart';

main() async {
  /// create a new graph to hold the data
  Graph g = Graph();

  /// need to use await keyword
  await g.parseEncrypted('example/ex1.enc.ttl', passphrase: 'helloworld!');
  print('Contexts:\n${g.contexts}');
  print('Data:\n${g.triples}');

  /// serialize it to specified location, should be equivalent to original file
  g.serialize(format: 'ttl', dest: 'example/ex1.dec.ttl');
}

3.2 Parsing long text string

import 'package:rdflib/rdflib.dart';

main() {
  // sample whole text file
  String text = """
#--rdflib--
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<https://solid.silo.net.au/charlie_bruegel> rdf:type owl:NamedIndividual ;
    <http://xmlns.com/foaf/0.1/name> "Charlie Bruegel"^^xsd:string ;
    <http://silo.net.au/predicates/analytic#bmiM> "0,3,2,6"^^xsd:string ;
    <http://silo.net.au/predicates/analytic#bmiF> "1,10,2,6"^^xsd:string ;
    <http://silo.net.au/predicates/analytic#bloodPressureM> "11,0,0,0"^^xsd:string ;
    <http://silo.net.au/predicates/analytic#bloodPressureF> "19,0,0,0"^^xsd:string ;
    <http://silo.net.au/predicates/analytic#cholesterolLevelM> "8,1,2"^^xsd:string ;
    <http://silo.net.au/predicates/analytic#cholesterolLevelF> "11,5,3"^^xsd:string ;
    <http://silo.net.au/predicates/analytic#smoking0> "26"^^xsd:string ;
    <http://silo.net.au/predicates/analytic#smoking1> "4"^^xsd:string ;
    <http://silo.net.au/predicates/analytic#bloodGlucoseReal> "8.1,8.0,7.9,7.7,7.6,7.8,7.3,7.1,6.9,6.7,6.3,6.6,6.4"^^xsd:string ;
    <http://silo.net.au/predicates/analytic#BMIList> "33,30,27,25,24"^^xsd:string .

  """;

  // create a graph to read turtle file and store info
  Graph g = Graph();
  g.parseText(text);

  // full format of triples (will use shorthand in serialization/export)
  for (Triple t in g.triples) {
    print(t);
  }

  // verify contexts
  print('Contexts: ${g.contexts}');

  // export it to a new file (should be equivalent to the original one)
  g.serialize(format: 'ttl', dest: 'example/ex_full_text.ttl');
}

Additional information

Useful resources

1. RDFLib
2. Introduction to RDF

How to contribute

Make a pull request on our GitHub repo!

Acknowledgement

This rdflib dart package is modelled on the RDFLib.