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custom_datatype

RDFLib can map between RDF data-typed literals and Python objects.

Mapping for integers, floats, dateTimes, etc. are already added, but you can also add your own.

This example shows how bind lets you register new mappings between literal datatypes and Python objects

Attributes:

EG module-attribute 

EG = Namespace('http://example.com/')

c module-attribute 

c = complex(2, 3)

g module-attribute 

g = Graph()

g2 module-attribute 

g2 = parse(data=serialize())

l module-attribute 

l = Literal(c)

l2 module-attribute 

l2 = list(g2)[0]

ce: false show_docstring_attributes: false show_docstring_functions: false show_docstring_modules: false show_docstring_classes: false show_signature: false show_signature_annotations: false show_signature_type_parameters: false show_docstring_other_parameters: false show_docstring_parameters: false show_docstring_raises: false show_docstring_receives: false show_docstring_returns: false summary: false show_if_no_docstring: false

from rdflib import XSD, Graph, Literal, Namespace, term

if __name__ == "__main__":
    # Complex numbers are not registered by default
    # No custom constructor/serializer needed since
    # complex('(2+3j)') works fine
    term.bind(XSD.complexNumber, complex)

    # Create a complex number RDFlib Literal
    EG = Namespace("http://example.com/")
    c = complex(2, 3)
    l = Literal(c)  # noqa: E741

    # Add it to a graph
    g = Graph()
    g.add((EG.mysubject, EG.myprop, l))
    # Print the triple to see what it looks like
    print(list(g)[0])
    # prints: (
    #           rdflib.term.URIRef('http://example.com/mysubject'),
    #           rdflib.term.URIRef('http://example.com/myprop'),
    #           rdflib.term.Literal(
    #               '(2+3j)',
    #               datatype=rdflib.term.URIRef('http://www.w3.org/2001/XMLSchema#complexNumber')
    #           )
    #         )

    # Round-trip through n3 serialize/parse
    g2 = Graph().parse(data=g.serialize())

    l2 = list(g2)[0]
    print(l2)

    # Compare with the original python complex object (should be True)
    # l2[2] is the object of the triple
    assert isinstance(l2[2], Literal)
    print(l2[2].value == c)