SHACL + SPARQL engine

The goal of this project is to provide a reference implementation of the SHACL 1.2 SPARQL extension.

Framework

The code uses:

• Python 3.14+.
• pySHACL
• RDFLib
• pyoxigraph, scoped to the one gap rdflib can't cover (RDF-star) — see ./docs/rdf-star-backend.md

Structure

• shacl_sparql.validate — typed wrapper around pyshacl.validate().
• shacl_sparql.conformance — static, non-executing scan of a shapes graph for SHACL 1.2 constructs the default pipeline can't evaluate, plus Appendix A pre-binding lint.
• shacl_sparql.extensions — opt-in closures for the SHACL 1.2 gaps that neither pyshacl nor rdflib implement natively (§5 result annotations, §6 node expressions, §7 custom functions, §8 layer/runOnce/expectedPredicate, RDF-star sh:tempTriple). Nothing here is wired into validate() automatically; conformance.check() names the construct so you know which extension to reach for.

Hello world

from shacl_sparql.validate import validate

# str sources are treated as file paths/URLs by rdflib; use bytes for inline Turtle.
shapes = b"""
@prefix sh: <http://www.w3.org/ns/shacl#> .
@prefix ex: <http://example.com/ns#> .

ex:PersonShape
    a sh:NodeShape ;
    sh:targetClass ex:Person ;
    sh:property [
        sh:path ex:name ;
        sh:minCount 1 ;
    ] .
"""

data = b"""
@prefix ex: <http://example.com/ns#> .

ex:Alice a ex:Person ;
    ex:name "Alice" .

ex:Bob a ex:Person .
"""

outcome = validate(data, shapes)
print(outcome.conforms)  # False — ex:Bob has no ex:name
print(outcome.report_text)

Hello world: SHACL + SPARQL constraint

A sh:sparql constraint runs an arbitrary SPARQL SELECT per focus node — any row it returns is a violation. Here it checks that ex:endDate comes after ex:startDate:

from shacl_sparql.validate import validate

shapes = b"""
@prefix sh: <http://www.w3.org/ns/shacl#> .
@prefix ex: <http://example.com/ns#> .

ex:EventShape
    a sh:NodeShape ;
    sh:targetClass ex:Event ;
    sh:sparql [
        a sh:SPARQLConstraint ;
        sh:message "ex:endDate must be after ex:startDate." ;
        sh:select \"\"\"
            PREFIX ex: <http://example.com/ns#>
            SELECT $this
            WHERE {
                $this ex:startDate ?start ;
                      ex:endDate ?end .
                FILTER (?end <= ?start)
            }
        \"\"\" ;
    ] .
"""

data = b"""
@prefix ex: <http://example.com/ns#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

ex:Conference a ex:Event ;
    ex:startDate "2026-09-01"^^xsd:date ;
    ex:endDate "2026-09-03"^^xsd:date .

ex:Workshop a ex:Event ;
    ex:startDate "2026-10-05"^^xsd:date ;
    ex:endDate "2026-10-01"^^xsd:date .
"""

outcome = validate(data, shapes)
print(outcome.conforms)  # False — ex:Workshop's endDate precedes its startDate
print(outcome.report_text)

Conformance

Every push runs the vendored W3C SHACL 1.2 SPARQL Extensions test suite and publishes the results as an EARL report — the standard machine-readable format for implementation conformance, so results can be aggregated alongside other implementations. Latest report (always up to date with main): w3c-earl-report.ttl.

Specification

Specification reference: https://www.w3.org/TR/shacl12-sparql/