How to remove edge between two vertices? - titan

Question

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.

Answer 1

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();
}