Arangodb Java-driver Sort paths

Question

Please, can you explain me how I can sort paths. Now I have next code

TraversalOptions options = new TraversalOptions()
                    .edgeCollection("edges")
                    .startVertex("nodes/9149892904413851091")
                    .verticesUniqueness(TraversalOptions.UniquenessType.path)
                    .direction(TraversalOptions.Direction.any)
                    .strategy(TraversalOptions.Strategy.depthfirst)
                    .order(TraversalOptions.Order.preorder)
                    .minDepth(5)
                    .maxDepth(5);
            System.out.println("1");
            TraversalEntity<BaseDocument, BaseEdgeDocument> traversal = 
            db.executeTraversal(BaseDocument.class, BaseEdgeDocument.class, options);

How I understand .sort method in options will sort edges. But I want to sort paths. Any ideas?

I need to test two cases: 1. sort by length of paths ( so I will find the shortest path) 2. sort by sum of relationships' weights (so i will be able to find a path with the less weight)

Answer 1

Achieving your goal is both easier and much more efficient using an AQL query than a Traversal.

A (parameterized) AQL query for a shortest path looks like this:

FOR v IN ANY SHORTEST_PATH
@startVertex TO @targetVertex
edges
RETURN v

To get a weighted shortest path (ie, shortest in terms of sum of the weights), just specify the name of the weight attribute:

FOR v IN ANY SHORTEST_PATH
@startVertex TO @targetVertex
edges
OPTIONS { weightAttribute: "weight" }
RETURN v

You can use an AQL query in Java like this:

// Set the query parameters
Map<String, Object> bindVars
    = new MapBuilder()
    .put("startVertex", "nodes/1234")
    .put("targetVertex", "nodes/5678")
    .get();

// execute the query
ArangoCursor<BaseDocument> cursor = arango.db("mydb").query(
    "FOR v IN ANY SHORTEST_PATH "
        + "@startVertex TO @targetVertex "
        + "edges "
        + "OPTIONS { weightAttribute: 'weight' } "
        + "RETURN v",
    bindVars,
    null,
    BaseDocument.class
);

// do something with the results
cursor.forEach((v) -> {
    System.out.println(v);
});