Apache TinkerPopAT
Apache TinkerPop•2y ago
Johan

Does the TinkerGraph in-memory database support List cardinality properties for vertices?

It is my understanding that the following code should work:
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal;
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversalSource;
import org.apache.tinkerpop.gremlin.structure.Vertex;
import org.apache.tinkerpop.gremlin.structure.VertexProperty;
import org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerGraph;
import org.junit.jupiter.api.Test;

import java.util.Map;

import static org.apache.tinkerpop.gremlin.process.traversal.AnonymousTraversalSource.traversal;

public class GremlinTest {

    @Test
    public void testGremlin() {
        try (TinkerGraph graph = TinkerGraph.open()) {
            GraphTraversalSource g = traversal().withEmbedded(graph);
            g.addV("CH")
                    .property("key", "123")
                    .property("age", 20)
                    .property("gender", "male")
                    .property(VertexProperty.Cardinality.list, "address", "a street, a city")
                    .property(VertexProperty.Cardinality.list, "address", "b street, b city")
                    .next();
            GraphTraversal<Vertex, Map<Object, Object>> traversal = g.V().hasLabel("CH").elementMap();
            while (traversal.hasNext()) {
                Map<Object, Object> node = traversal.next();
                System.out.printf("%s", node);
            }
        }
    }
}

The output when this is executed is:
{id=0, label=CH, address=b street, b city, gender=male, key=123, age=20}

However, I would expect its output to be something like this:
{id=0, label=CH, address=["a street, a city", "b street, b city"], gender=male, key=123, age=20}


Does anyone know what I am doing wrong here?
Solution
elementMap() assumes that cardinality for each key is single and if it is list then only the first item encountered will be returned.
To get all property values valueMap() step can be used instead.
gremlin> g.V(1).property("address", "a1").property(list, "address", "a2") ==>v[1] gremlin> g.V(1).valueMap() ==>[address:[a1,a2],name:[marko],age:[29]] gremlin> g.V(1).elementMap() ==>[id:1,label:person,address:a2,name:marko,age:29]
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