verifiedPattern — Load → Validate → Query

Check a graph against SHACL shapes and act on the verdict — gate ingestion, alert, or only query what conforms. This page walks the whole journey on real data, with the real report.

When to use it

You want a conformance gate — refuse data that violates your shapes, or surface the violations as data. Put Reason before Validate when the shapes constrain entailed facts; skip it when they constrain only asserted triples. Both are single-threaded, so size the graph to your box.

A worked scenario — required fields

A Person dataset where one record is incomplete. We require every person to have a name and an age, load two records — one complete, one missing its age — and watch validation catch exactly the incomplete one.

Step 1 — load the data

SELECT pgrdf.add_graph(8971);
SELECT pgrdf.parse_turtle('
@prefix ex:   <http://example.org/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#> .

ex:alice a foaf:Person ; foaf:name "Alice" .                          # no ex:age
ex:bob   a foaf:Person ; foaf:name "Bob" ; ex:age "30"^^xsd:integer .
', 8971);

Alice has a name but no age; Bob has both.

Step 2 — load the shapes

SELECT pgrdf.add_graph(8972);
SELECT pgrdf.parse_turtle('
@prefix ex:   <http://example.org/> .
@prefix sh:   <http://www.w3.org/ns/shacl#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#> .

ex:PersonShape a sh:NodeShape ;
    sh:targetClass foaf:Person ;
    sh:property [ sh:path foaf:name ; sh:minCount 1 ; sh:datatype xsd:string  ] ;
    sh:property [ sh:path ex:age   ; sh:minCount 1 ; sh:datatype xsd:integer ] .
', 8972);

Every foaf:Person must carry at least one name and one integer age.

Step 3 — validate

SELECT pgrdf.validate(8971, 8972);

pgRDF returns a W3C sh:ValidationReport as JSONB:

{
  "conforms": false,
  "data_graph_id": 8971,
  "shapes_graph_id": 8972,
  "results": [
    {
      "focusNode": "http://example.org/alice",
      "resultPath": "http://example.org/age",
      "resultSeverity": "sh:Violation",
      "sourceConstraintComponent": "sh:MinCountConstraintComponent"
    }
  ]
}

Reading the report

• conforms is false — at least one node violates the shapes.
• One result, and it is Alice — on ex:age, a sh:Violation from the minCount constraint: she is missing the required age.
• Bob is absent from results — he conforms, so a gate built on this report lets him through and stops Alice.

Grounded in the test suite

This is tests/regression/sql/71-shacl-real.sql, gated in CI: the test asserts conforms = false, that Alice must appear as a violating focus node, that Bob must not, and that every result carries sh:Violation severity and a sourceConstraintComponent.

Acting on the report

The report is JSONB, so the gate is plain SQL:

SELECT (pgrdf.validate(8971, 8972) ->> 'conforms')::boolean AS ok;
--  → f

Branch on ok to accept or reject the load, or unfold the violations to act on each one:

SELECT res ->> 'focusNode' AS node,
       res ->> 'resultPath' AS path
FROM jsonb_array_elements(pgrdf.validate(8971, 8972) -> 'results') AS res;
--  → node = http://example.org/alice | path = http://example.org/age

See Report as data for the full report shape.

Variation — validate the entailed graph

When your shapes constrain facts that follow from the ontology (class membership, inverses), Reason first so validation sees the closure, not just the asserted triples:

SELECT pgrdf.materialize(8971, 'owl-rl');   -- entail first
SELECT pgrdf.validate(8971, 8972);          -- then validate the closure

This is the amber Reason → Validate segment of the chain above.

Next step

For a source larger than one backend can hold, carve a slice first: Ingest → Carve → Reason, then validate the slice.