Cast XML Datatypes in SPARQL query results to native Python types?

[dhimmel]

I've begun using rdflib to query OWL ontologies using SPARQL. Thanks for this Python tool!

Currently, I am using the API like:

results = graph.query(query) # graph is a rdflib.graph.Graph, and query is a string
result = results.bindings[0]

If we then look at result:

{
    rdflib.term.Variable('sub_efo_uri'): rdflib.term.URIRef('http://www.ebi.ac.uk/efo/EFO_0002508'), 
    rdflib.term.Variable('boolean_col'): rdflib.term.Literal('false', datatype=rdflib.term.URIRef('http://www.w3.org/2001/XMLSchema#boolean')),
    rdflib.term.Variable('count'): rdflib.term.Literal('1', datatype=rdflib.term.URIRef('http://www.w3.org/2001/XMLSchema#integer')),
}

Values are wrapped in rdflib.term.* objects. I noticed in these docs, a reference to the internal function rdflib.term._castLexicalToPython.

What is the recommended way to cast XML Datatypes from a SPARQL query result to native Python types? In my case, something that would produce output like:

{
    'sub_efo_uri': 'http://www.ebi.ac.uk/efo/EFO_0002508', 
    'boolean_col': False,
    'count': 1,
}

Is there a straightforward way to get SPARQL results with Python types this I am overlooking?

[dhimmel]

@matentzn provided the answer to my question in RDFLib/sparqlwrapper#125 (comment): the .toPython() method!

What is the recommended way to cast XML Datatypes from a SPARQL query result to native Python types? In my case, something that would produce output like:

The following extension of the above code gets the desired output:

{str(k): None if v is None else v.toPython() for k, v in result.items()}

There are two actionable changes that could be considered:

1. expanding the documentation to mention .toPython(). Currently, it's used in an example (lit2006.toPython()), but much less obvious than the internal method rdflib.term._castLexicalToPython.

2. adding a method/property to rdflib.plugins.sparql.processor.SPARQLResult to make accessing .toPython values easy. For example, something like SPARQLResult.python_bindings, which would be like bindings but using native Python types. I am guessing this is what most users want when they make a query.