rdflib 0.1.9 rdflib: ^0.1.9 copied to clipboard
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 withAES
encryption
- Export to encrypted turtle
- 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 usingAES
- Parse long text string stored in memory
- Parse encrypted turtle
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:
- Create a
Graph
instance; - Create and store
triple
s with different data types; - Find entities based on customized criteria;
- Bind shorted string to long
namespace
; - 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:donna@example.org')));
// 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.scissorhands@example.org', 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:donna@example.org) and
// Literal(e.scissorhands@example.org, 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 #
How to contribute #
Make a pull request on our GitHub repo!
Acknowledgement #
This rdflib
dart package is modelled on the RDFLib.