Neo4j重新排序路徑

Question

Neo4j中是否有（可能使用PathExpander或RelationshipExpander）重新排序遍歷java中的關係屬性（在我的情況下是時間戳）的路徑？

我已經搜索了幾乎所有的api和社區討論，但無法找到提示。

Answer 1

您可能會創建一個路徑擴展器，根據該屬性的值來擴展路徑，如下所示（假設您希望增加順序）。

public class OrderPathExpander implements PathExpander<String> { 

private final RelationshipType relationshipType; 
private final Direction direction; 

public OrderPathExpander(RelationshipType relationshipType, Direction direction) 
{ 
    this.relationshipType = relationshipType; 
    this.direction = direction; 
} 
@Override 
public Iterable<Relationship> expand(Path path, BranchState<String> state) 
{ 
    List<Relationship> results = new ArrayList<Relationship>(); 
    if (path.length() == 0) { 
     for (Relationship r : path.endNode().getRelationships(relationshipType, direction)) 
     { 
       results.add(r); 

     } 

    } 
    else { 
    for (Relationship r : path.endNode().getRelationships(relationshipType, direction)) 
    { 
     if (r.getProperty("timestamp") >= (path.lastRelationship().getProperty("timestamp")) ) 
     { 
      results.add(r); 
     } 
    } 
    } 
    return results; 
} 
@Override 
public PathExpander<String> reverse() 
{ 
    return null; 
} 

}

然後用你的路延長你的traveral，

TraversalDescription td = Traversal.description() 
     .breadthFirst() 
     .expand(new OrderPathExpander(YourRelationshipType, Direction.INCOMING)) 
     .evaluator(new Evaluator() {...});