java - 分配给变量时，我可以以某种方式重用 Gremlin GraphTraversals 代码吗？

Question

我有看起来像那样的 GraphTraversals(attrGroup:

GraphTraversal<Vertex,Edge> attrGroupTraversal = some code generates it; 
List<Vertex> attributeVs = attrGroupTraversal.inV().out(EdgeLabels.ContainsAttribute).toList();
List<Vertex> sourceVs = attrGroupTraversal.inV().out(EdgeLabels.ContainsSource).toList();
List<Vertex> targetVs = attrGroupTraversal.out(EdgeLabels.ContainsTarget).toList();

有没有办法重用 attrGroupTraversal，这样我就不需要重新运行最初创建它的代码？

我得到:

java.lang.IllegalStateException: The traversal strategies are complete and the traversal can no longer be modulated

at org.apache.tinkerpop.gremlin.process.traversal.Traversal$Exceptions.traversalIsLocked(Traversal.java:245) at org.apache.tinkerpop.gremlin.process.traversal.util.DefaultTraversal.addStep(DefaultTraversal.java:274) at org.apache.tinkerpop.gremlin.process.traversal.Traversal$Admin.addStep(Traversal.java:301) at org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal$Admin.addStep(GraphTraversal.java:170) at org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal.inV(GraphTraversal.java:384)

Answer 1

我建议你 .clone() 你原来的遍历。以下应该有效:

GraphTraversal<Vertex,Edge> attrGroupTraversal = some code generates it; 
List<Vertex> attributeVs = attrGroupTraversal.clone().inV().out(EdgeLabels.ContainsAttribute).toList();
List<Vertex> sourceVs = attrGroupTraversal.clone().inV().out(EdgeLabels.ContainsSource).toList();
List<Vertex> targetVs = attrGroupTraversal.clone().out(EdgeLabels.ContainsTarget).toList();

另请参阅:Traversal component reuse来自 TinkerPop 文档食谱。