# -*- coding: utf-8 -*-
from rdflib import py3compat
__doc__ = py3compat.format_doctest_out("""
The :class:`~rdflib.resource.Resource` class wraps a
:class:`~rdflib.graph.Graph`
and a resource reference (i.e. a :class:`rdflib.term.URIRef` or
:class:`rdflib.term.BNode`) to support a resource-oriented way of
working with a graph.
It contains methods directly corresponding to those methods of the Graph
interface that relate to reading and writing data. The difference is that a
Resource also binds a resource identifier, making it possible to work without
tracking both the graph and a current subject. This makes for a "resource
oriented" style, as compared to the triple orientation of the Graph API.
Resulting generators are also wrapped so that any resource reference values
(:class:`rdflib.term.URIRef`s and :class:`rdflib.term.BNode`s) are in turn
wrapped as Resources. (Note that this behaviour differs from the corresponding
methods in :class:`~rdflib.graph.Graph`, where no such conversion takes place.)
Basic Usage Scenario
--------------------
Start by importing things we need and define some namespaces::
>>> from rdflib import *
>>> FOAF = Namespace("http://xmlns.com/foaf/0.1/")
>>> CV = Namespace("http://purl.org/captsolo/resume-rdf/0.2/cv#")
Load some RDF data::
>>> graph = Graph().parse(format='n3', data='''
... @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
... @prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
... @prefix foaf: <http://xmlns.com/foaf/0.1/> .
... @prefix cv: <http://purl.org/captsolo/resume-rdf/0.2/cv#> .
...
... @base <http://example.org/> .
...
... </person/some1#self> a foaf:Person;
... rdfs:comment "Just a Python & RDF hacker."@en;
... foaf:depiction </images/person/some1.jpg>;
... foaf:homepage <http://example.net/>;
... foaf:name "Some Body" .
...
... </images/person/some1.jpg> a foaf:Image;
... rdfs:label "some 1"@en;
... rdfs:comment "Just an image"@en;
... foaf:thumbnail </images/person/some1-thumb.jpg> .
...
... </images/person/some1-thumb.jpg> a foaf:Image .
...
... [] a cv:CV;
... cv:aboutPerson </person/some1#self>;
... cv:hasWorkHistory [ cv:employedIn </#company>;
... cv:startDate "2009-09-04"^^xsd:date ] .
... ''')
Create a Resource::
>>> person = Resource(
... graph, URIRef("http://example.org/person/some1#self"))
Retrieve some basic facts::
>>> person.identifier
rdflib.term.URIRef(%(u)s'http://example.org/person/some1#self')
>>> person.value(FOAF.name)
rdflib.term.Literal(%(u)s'Some Body')
>>> person.value(RDFS.comment)
rdflib.term.Literal(%(u)s'Just a Python & RDF hacker.', lang=%(u)s'en')
Resources can be sliced (like graphs, but the subject is fixed)::
>>> for name in person[FOAF.name]:
... print(name)
Some Body
>>> person[FOAF.name : Literal("Some Body")]
True
Resources as unicode are represented by their identifiers as unicode::
>>> %(unicode)s(person) #doctest: +SKIP
%(u)s'Resource(http://example.org/person/some1#self'
Resource references are also Resources, so you can easily get e.g. a qname
for the type of a resource, like::
>>> person.value(RDF.type).qname()
%(u)s'foaf:Person'
Or for the predicates of a resource::
>>> sorted(
... p.qname() for p in person.predicates()
... ) #doctest: +NORMALIZE_WHITESPACE +SKIP
[%(u)s'foaf:depiction', %(u)s'foaf:homepage',
%(u)s'foaf:name', %(u)s'rdf:type', %(u)s'rdfs:comment']
Follow relations and get more data from their Resources as well::
>>> for pic in person.objects(FOAF.depiction):
... print(pic.identifier)
... print(pic.value(RDF.type).qname())
... print(pic.label())
... print(pic.comment())
... print(pic.value(FOAF.thumbnail).identifier)
http://example.org/images/person/some1.jpg
foaf:Image
some 1
Just an image
http://example.org/images/person/some1-thumb.jpg
>>> for cv in person.subjects(CV.aboutPerson):
... work = list(cv.objects(CV.hasWorkHistory))[0]
... print(work.value(CV.employedIn).identifier)
... print(work.value(CV.startDate))
http://example.org/#company
2009-09-04
It's just as easy to work with the predicates of a resource::
>>> for s, p in person.subject_predicates():
... print(s.value(RDF.type).qname())
... print(p.qname())
... for s, o in p.subject_objects():
... print(s.value(RDF.type).qname())
... print(o.value(RDF.type).qname())
cv:CV
cv:aboutPerson
cv:CV
foaf:Person
This is useful for e.g. inspection::
>>> thumb_ref = URIRef("http://example.org/images/person/some1-thumb.jpg")
>>> thumb = Resource(graph, thumb_ref)
>>> for p, o in thumb.predicate_objects():
... print(p.qname())
... print(o.qname())
rdf:type
foaf:Image
Similarly, adding, setting and removing data is easy::
>>> thumb.add(RDFS.label, Literal("thumb"))
>>> print(thumb.label())
thumb
>>> thumb.set(RDFS.label, Literal("thumbnail"))
>>> print(thumb.label())
thumbnail
>>> thumb.remove(RDFS.label)
>>> list(thumb.objects(RDFS.label))
[]
Schema Example
--------------
With this artificial schema data::
>>> graph = Graph().parse(format='n3', data='''
... @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
... @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
... @prefix owl: <http://www.w3.org/2002/07/owl#> .
... @prefix v: <http://example.org/def/v#> .
...
... v:Artifact a owl:Class .
...
... v:Document a owl:Class;
... rdfs:subClassOf v:Artifact .
...
... v:Paper a owl:Class;
... rdfs:subClassOf v:Document .
...
... v:Choice owl:oneOf (v:One v:Other) .
...
... v:Stuff a rdf:Seq; rdf:_1 v:One; rdf:_2 v:Other .
...
... ''')
From this class::
>>> artifact = Resource(graph, URIRef("http://example.org/def/v#Artifact"))
we can get at subclasses::
>>> subclasses = list(artifact.transitive_subjects(RDFS.subClassOf))
>>> [c.qname() for c in subclasses]
[%(u)s'v:Artifact', %(u)s'v:Document', %(u)s'v:Paper']
and superclasses from the last subclass::
>>> [c.qname() for c in subclasses[-1].transitive_objects(RDFS.subClassOf)]
[%(u)s'v:Paper', %(u)s'v:Document', %(u)s'v:Artifact']
Get items from the Choice::
>>> choice = Resource(graph, URIRef("http://example.org/def/v#Choice"))
>>> [it.qname() for it in choice.value(OWL.oneOf).items()]
[%(u)s'v:One', %(u)s'v:Other']
And the sequence of Stuff::
>>> stuff = Resource(graph, URIRef("http://example.org/def/v#Stuff"))
>>> [it.qname() for it in stuff.seq()]
[%(u)s'v:One', %(u)s'v:Other']
On add, other resources are auto-unboxed:
>>> paper = Resource(graph, URIRef("http://example.org/def/v#Paper"))
>>> paper.add(RDFS.subClassOf, artifact)
>>> artifact in paper.objects(RDFS.subClassOf) # checks Resource instance
True
>>> (paper._identifier, RDFS.subClassOf, artifact._identifier) in graph
True
Technical Details
-----------------
Comparison is based on graph and identifier::
>>> g1 = Graph()
>>> t1 = Resource(g1, URIRef("http://example.org/thing"))
>>> t2 = Resource(g1, URIRef("http://example.org/thing"))
>>> t3 = Resource(g1, URIRef("http://example.org/other"))
>>> t4 = Resource(Graph(), URIRef("http://example.org/other"))
>>> t1 is t2
False
>>> t1 == t2
True
>>> t1 != t2
False
>>> t1 == t3
False
>>> t1 != t3
True
>>> t3 != t4
True
>>> t3 < t1 and t1 > t3
True
>>> t1 >= t1 and t1 >= t3
True
>>> t1 <= t1 and t3 <= t1
True
>>> t1 < t1 or t1 < t3 or t3 > t1 or t3 > t3
False
Hash is computed from graph and identifier::
>>> g1 = Graph()
>>> t1 = Resource(g1, URIRef("http://example.org/thing"))
>>> hash(t1) == hash(Resource(g1, URIRef("http://example.org/thing")))
True
>>> hash(t1) == hash(Resource(Graph(), t1.identifier))
False
>>> hash(t1) == hash(Resource(Graph(), URIRef("http://example.org/thing")))
False
The Resource class is suitable as a base class for mapper toolkits. For
example, consider this utility for accessing RDF properties via qname-like
attributes::
>>> class Item(Resource):
...
... def __getattr__(self, p):
... return list(self.objects(self._to_ref(*p.split('_', 1))))
...
... def _to_ref(self, pfx, name):
... return URIRef(self._graph.store.namespace(pfx) + name)
It works as follows::
>>> graph = Graph().parse(format='n3', data='''
... @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
... @prefix foaf: <http://xmlns.com/foaf/0.1/> .
...
... @base <http://example.org/> .
... </person/some1#self>
... foaf:name "Some Body";
... foaf:depiction </images/person/some1.jpg> .
... </images/person/some1.jpg> rdfs:comment "Just an image"@en .
... ''')
>>> person = Item(graph, URIRef("http://example.org/person/some1#self"))
>>> print(person.foaf_name[0])
Some Body
The mechanism for wrapping references as resources cooperates with subclasses.
Therefore, accessing referenced resources automatically creates new ``Item``
objects::
>>> isinstance(person.foaf_depiction[0], Item)
True
>>> print(person.foaf_depiction[0].rdfs_comment[0])
Just an image
""")
from rdflib.term import Node, BNode, URIRef
from rdflib.namespace import RDF
from rdflib.paths import Path
__all__ = ['Resource']
[docs]class Resource(object):
[docs] def __init__(self, graph, subject):
self._graph = graph
self._identifier = subject
graph = property(lambda self: self._graph)
identifier = property(lambda self: self._identifier)
[docs] def __hash__(self):
return hash(Resource) ^ hash(self._graph) ^ hash(self._identifier)
[docs] def __eq__(self, other):
return (isinstance(other, Resource) and
self._graph == other._graph and
self._identifier == other._identifier)
__ne__ = lambda self, other: not self == other
[docs] def __lt__(self, other):
if isinstance(other, Resource):
return self._identifier < other._identifier
else:
return False
__gt__ = lambda self, other: not (self < other or self == other)
__le__ = lambda self, other: self < other or self == other
__ge__ = lambda self, other: not self < other
[docs] def __unicode__(self):
return unicode(self._identifier)
if py3compat.PY3:
__str__ = __unicode__
[docs] def add(self, p, o):
if isinstance(o, Resource):
o = o._identifier
self._graph.add((self._identifier, p, o))
[docs] def remove(self, p, o=None):
if isinstance(o, Resource):
o = o._identifier
self._graph.remove((self._identifier, p, o))
[docs] def set(self, p, o):
if isinstance(o, Resource):
o = o._identifier
self._graph.set((self._identifier, p, o))
[docs] def subjects(self, predicate=None): # rev
return self._resources(
self._graph.subjects(predicate, self._identifier))
[docs] def predicates(self, o=None):
if isinstance(o, Resource):
o = o._identifier
return self._resources(
self._graph.predicates(self._identifier, o))
[docs] def objects(self, predicate=None):
return self._resources(
self._graph.objects(self._identifier, predicate))
[docs] def subject_predicates(self):
return self._resource_pairs(
self._graph.subject_predicates(self._identifier))
[docs] def subject_objects(self):
return self._resource_pairs(
self._graph.subject_objects(self._identifier))
[docs] def predicate_objects(self):
return self._resource_pairs(
self._graph.predicate_objects(self._identifier))
[docs] def value(self, p=RDF.value, o=None, default=None, any=True):
if isinstance(o, Resource):
o = o._identifier
return self._cast(
self._graph.value(self._identifier, p, o, default, any))
[docs] def label(self):
return self._graph.label(self._identifier)
[docs] def items(self):
return self._resources(self._graph.items(self._identifier))
[docs] def transitive_objects(self, predicate, remember=None):
return self._resources(self._graph.transitive_objects(
self._identifier, predicate, remember))
[docs] def transitive_subjects(self, predicate, remember=None):
return self._resources(self._graph.transitive_subjects(
predicate, self._identifier, remember))
[docs] def seq(self):
return self._resources(self._graph.seq(self._identifier))
[docs] def qname(self):
return self._graph.qname(self._identifier)
def _resource_pairs(self, pairs):
for s1, s2 in pairs:
yield self._cast(s1), self._cast(s2)
def _resource_triples(self, triples):
for s,p,o in triples:
yield self._cast(s), self._cast(p), self._cast(o)
def _resources(self, nodes):
for node in nodes:
yield self._cast(node)
def _cast(self, node):
if isinstance(node, (BNode, URIRef)):
return self._new(node)
else:
return node
[docs] def __iter__(self):
return self._resource_triples(self._graph.triples((self.identifier, None, None)))
[docs] def __getitem__(self, item):
if isinstance(item, slice):
if item.step:
raise TypeError("Resources fix the subject for slicing, and can only be sliced by predicate/object. ")
p,o=item.start,item.stop
if isinstance(p, Resource): p = p._identifier
if isinstance(o, Resource): o = o._identifier
if p is None and o is None:
return self.predicate_objects()
elif p is None:
return self.predicates(o)
elif o is None:
return self.objects(p)
else:
return (self.identifier, p, o) in self._graph
elif isinstance(item, (Node, Path)):
return self.objects(item)
else:
raise TypeError("You can only index a resource by a single rdflib term, a slice of rdflib terms, not %s (%s)"%(item, type(item)))
[docs] def __setitem__(self, item, value):
self.set(item, value)
def _new(self, subject):
return type(self)(self._graph, subject)
[docs] def __str__(self):
return 'Resource(%s)' % self._identifier
[docs] def __repr__(self):
return 'Resource(%s,%s)' % (self._graph, self._identifier)