Retrieve content of a BNode

[rracariu]

Got a SHACL graph where shapes have properties, in short form:

ex:Foo a owl:Class,
        sh:NodeShape ;
    sh:property [ sh:class ex:Bar ;
            sh:path ex:somePath ] .

When collecting the triples for Foo, I get a bnode for the sh:property, and that is in the form of an opaque reference, like _:riog00007686
Is there a way to get the triples inside that bnode?

[pchampin]

Triples are not "inside" a node (blank or otherwise). The square brackets are just a shortcut to spare you the trouple of "labelling" the blank node, but internally, all blank node get an arbitrary label. So your Turtle is equivalent to:

ex:Foo a owl:Class .
ex:Foo a sh:NodeShape .
ex:Foo sh:property _:b .
_:b sh:class ex:Bar .
_:b sh:path ex:somePath .

In order to get all the triples from a graph g whose subject is a given blank node bn that you got, you can use Graph::triples_matching. For example:

for triple in g.triples_matching([b], Any, Any) {
  // do something with the triple
}

A more elaborate example would be:

    let mut graph: LightGraph = turtle::parse_str(your_data).collect_triples()?;

    let ex = Namespace::new("http://example.org/")?;
    let sh = Namespace::new("http://www.w3.org/ns/shacl#")?;

    // retrieve all sh:properties of ex:Foo
    for t1 in graph.triples_matching([ex.get("Foo")?], [sh.get("property")?], Any) {
        let prop = t1?.p();
        // retrieve all the triples describing `prop`
        for triple in graph.triples_matching([prop], Any, Any) {
            // do something with the triple
        }
    }

[rracariu]

Thanks for the explanation and this awesome library!

I was able to get it going with something like:

let ex = Namespace::new("http://example.org/")?;
let sh = Namespace::new("http://www.w3.org/ns/shacl#")?;

let class = ex.get("Foo")?;
let prop = sh.get("property")?;
    
for prop_term in self
        .graph
        .triples_matching(&class, &prop, &ANY)
        .map(|triple| triple.map(|el| el.o().clone()))
    {
        let prop_term = prop_term?;
        for triple in self.graph.triples_matching(&prop_term, &ANY, &ANY) {
            let triple = triple?;
            let name = triple.p().value().to_string();
            let value = triple.o().value().to_string();
            println!("{name}: {value}")
        }
    }