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