rdflib-orm

A Python ORM for working with RDF.

Usage

from rdflib import Graph
from rdflib.namespace import DCTERMS, SKOS, OWL, DCAT, RDFS, RDF

from rdflib_orm.db import Database
from rdflib_orm import models


class Common(models.Model):
 provenance = models.CharField(predicate=DCTERMS.provenance, lang='en', required=True)

 class Meta:
  mixin = True


class ConceptScheme(Common):
 class_type = models.IRIField(predicate=RDF.type, value=SKOS.ConceptScheme)
 title = models.CharField(predicate=DCTERMS.title, lang='en', required=True)
 description = models.CharField(predicate=SKOS.definition, lang='en', required=True)
 created = models.DateTimeField(DCTERMS.created, auto_now_add=True)
 modified = models.DateTimeField(DCTERMS.modified, auto_now=True)
 creator = models.IRIField(predicate=DCTERMS.creator, required=True)
 publisher = models.IRIField(predicate=DCTERMS.publisher, required=True)
 version = models.CharField(predicate=OWL.versionInfo, required=True)
 custodian = models.CharField(predicate=DCAT.contactPoint)
 see_also = models.IRIField(predicate=RDFS.seeAlso, many=True)

 def __repr__(self):
  return f'<{self.__uri__}>'


class Concept(Common):
 class_type = models.IRIField(predicate=RDF.type, value=SKOS.Concept)
 pref_label = models.CharField(predicate=SKOS.prefLabel, lang='en', required=True)
 alt_labels = models.CharField(predicate=SKOS.altLabel, lang='en', many=True)
 definition = models.CharField(predicate=SKOS.definition, lang='en', required=True)
 children = models.IRIField(predicate=SKOS.narrower, many=True, inverse=SKOS.broader)
 other_ids = models.CharField(predicate=SKOS.notation, many=True)
 home_vocab_uri = models.IRIField(predicate=RDFS.isDefinedBy)

 def __repr__(self):
  return f'<{self.__uri__}>'


if __name__ == '__main__':
 g = Graph()
 g.bind('dcterms', DCTERMS)
 g.bind('skos', SKOS)
 g.bind('dcat', DCAT)
 g.bind('owl', OWL)
 Database.set_db(g, base_uri='http://example.com/')

 concept_scheme = ConceptScheme(
  'https://linked.data.gov.au/def/concept_scheme',
  title='A concept scheme',
  description='A description of this concept scheme.',
  creator='https://linked.data.gov.au/org/cgi',  # Accepts a URIRef or a string since the field is an IRIField.
  publisher='https://linked.data.gov.au/org/ga',
  version='0.1.0',
  provenance='Generated using Python',
  custodian='A custodian name',
  see_also=['http://example.com', 'http://another.example.com']  # Accepts a Python list since Field's many=True
 )

 concept_scheme.save()  # Save to store - currently memory store, but works also for remote triplestore.

 concept_scheme.title = 'Modified concept scheme title'
 concept_scheme.save()  # Save changes - we changed the title field.

 concept_a = Concept(
  uri='https://linked.data.gov.au/def/concept_a',
  pref_label='A concept',
  alt_labels=['An alt label', 'another alt label'],
  definition='Definition of this concept.',
  # children=  # Optional field, no children on this concept.
  other_ids=['123', '456'],  # No language tag here :)
  home_vocab_uri=concept_scheme,  # Reference the Concept Scheme Python object directly.
  provenance='Generated using RDFLib',
 )

 concept_a.save()

 concept_b = Concept(
  uri='https://linked.data.gov.au/def/concept_b',
  pref_label='Another concept',
  # alt_labels=  # Alt labels are optional.
  definition='Definition is not optional.',
  children=[concept_a],
  # Reference the previous concept Python object directly. Notice it will also add the inverse property :)
  # other_ids=  # Optional field again.
  home_vocab_uri=concept_scheme,
  provenance='Generated using rdflib-orm',
 )

 concept_b.save()

 # Let's do some queries.
 queryset = Concept.objects.all()
 print(queryset)
 # <QuerySet [<https://linked.data.gov.au/def/concept_b>, <https://linked.data.gov.au/def/concept_a>]>

 # Get object by URI.
 concept_result = Concept.objects.get('https://linked.data.gov.au/def/concept_a')
 print(concept_result)
 # <https://linked.data.gov.au/def/concept_a>
 print(concept_result.pref_label)
 # A concept
 print(concept_result.definition)
 # Definition of this concept.

 # Not implemented yet. Something planned for the future.
 # Get object by any property, e.g. notation.
 # concept_result = Concept.objects.get(other_ids=123)

 print(len(g))  # 28 triples

 g.serialize('output.ttl', format='turtle')
 """ # Output of Graph.serialize()
@prefix dcat: <http://www.w3.org/ns/dcat#> .
@prefix dcterms: <http://purl.org/dc/terms/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<https://linked.data.gov.au/def/concept_a> a skos:Concept ;
 dcterms:provenance "Generated using RDFLib"@en ;
 rdfs:isDefinedBy <https://linked.data.gov.au/def/concept_scheme> ;
 skos:altLabel "An alt label",
     "another alt label" ;
 skos:broader <https://linked.data.gov.au/def/concept_b> ;
 skos:definition "Definition of this concept."@en ;
 skos:notation "123",
     "456" ;
 skos:prefLabel "A concept"@en .

<https://linked.data.gov.au/def/concept_b> a skos:Concept ;
 dcterms:provenance "Generated using rdflib-orm"@en ;
 rdfs:isDefinedBy <https://linked.data.gov.au/def/concept_scheme> ;
 skos:definition "Definition is not optional."@en ;
 skos:narrower <https://linked.data.gov.au/def/concept_a> ;
 skos:prefLabel "Another concept"@en .

<https://linked.data.gov.au/def/concept_scheme> a skos:ConceptScheme ;
 dcterms:created "2021-05-26T22:13:50.720468"^^xsd:dateTime ;
 dcterms:creator <https://linked.data.gov.au/org/cgi> ;
 dcterms:modified "2021-05-26T22:13:50.723468"^^xsd:dateTime ;
 dcterms:provenance "Generated using Python"@en ;
 dcterms:publisher <https://linked.data.gov.au/org/ga> ;
 dcterms:title "Modified concept scheme title"@en ;
 rdfs:seeAlso <http://another.example.com>,
     <http://example.com> ;
 owl:versionInfo "0.1.0" ;
 skos:definition "A description of this concept scheme."@en ;
 dcat:contactPoint "A custodian name" .
 """

Running tests

pytest --cov=rdflib_orm --cov-report html