CODEWITHSUNDEEP
titangremlintinkerpop3
MichaelP
MichaelP

Reputation: 2781

How to remove edge between two vertices?

I want to remove edge between two vertices, so my code in java tinkerpop3 as below

private void removeEdgeOfTwoVertices(Vertex fromV, Vertex toV,String edgeLabel,GraphTraversalSource g){
        if(g.V(toV).inE(edgeLabel).bothV().hasId(fromV.id()).hasNext()){
            List<Edge> edgeList = g.V(toV).inE(edgeLabel).toList();
            for (Edge edge:edgeList){
                if(edge.outVertex().id().equals(fromV.id())) {
                    TitanGraph().tx();
                    edge.remove();                    
                    TitanGraph().tx().commit();
                    return;//Remove edge ok, now return.
                }
            }
        }
    }

Is there a simpler way to remove edge between two vertices by a direct query to that edge and remove it? Thank for your help.

Upvotes: 11

Views: 13679

Answers (1)

stephen mallette
stephen mallette

Reputation: 46226

Here's an example of how to drop edges between two vertices (where you just have the ids of those vertices:

gremlin> graph = TinkerFactory.createModern()
==>tinkergraph[vertices:6 edges:6]
gremlin> g = graph.traversal()
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> g.V(1).bothE()
==>e[9][1-created->3]
==>e[7][1-knows->2]
==>e[8][1-knows->4]

For purpose of the example, let's say we want to drop edges between vertex 1 and vertex 2. We could find those with:

gremlin> g.V(1).bothE().where(otherV().hasId(2))
==>e[7][1-knows->2]

and then remove it with:

gremlin> g.V(1).bothE().where(otherV().hasId(2)).drop()
gremlin> g.V(1).bothE()
==>e[9][1-created->3]
==>e[8][1-knows->4]

If you have the actual vertices, then you could just do:

gremlin> g.V(v1).bothE().where(otherV().is(v2)).drop()
gremlin> g.V(1).bothE()
==>e[9][1-created->3]
==>e[8][1-knows->4]

You could re-write your function as:

private void removeEdgeOfTwoVertices(Vertex fromV, Vertex toV,String edgeLabel,GraphTraversalSource g){
    g.V(fromV).bothE().hasLabel(edgeLabel).where(__.otherV().is(toV)).drop().iterate();
    g.tx().commit();    
}

Upvotes: 23

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