Question

我试着按照文档进行操作，最后我得到了Neo4j 1.8的这段代码：

graphDB = new GraphDatabaseFactory()
            .newEmbeddedDatabaseBuilder( BASE_FOLDER + NEO4J_PATH )
            .newGraphDatabase();

registerShutdownHook();

//Check if there are any indexes
System.out.println(Arrays.toString(graphDB.index().nodeIndexNames()));
Index<Node> testIndex = graphDB.index().forNodes("test");

Transaction tx = graphDB.beginTx();
try {
    String nameKey = "name";
    String nameValue = "Gevorg";

    //The following 3 lines will be commented out 
    //when I run the program the second time
    Node me = graphDB.createNode();
    me.setProperty(nameKey, nameValue);
    testIndex.add(me, nameKey, nameValue);

    Node meAgain = testIndex.get(nameKey, nameValue).getSingle();
    System.out.println(meAgain.getProperty(nameKey));

} finally {
    tx.finish();
}

按预期打印以下内容：

[] //There is no index at the very beginning
Gevorg

程序终止后，我评论了节点/索引的创建，然后再次运行程序以达到NullPointerException（meAgain为null）。由于程序首先打印[test]但是Node meAgain = testIndex.get(nameKey, nameValue).getSingle();无法检索节点，因此正确检索索引。我在使用和不使用交易的情况下都尝试了。我做错了什么？

Answer 1

在致电tx.finish

之前，您需要将Tx标记为成功

tx.success()

HTH

/彼得

Neo4j索引找不到Node

1 个答案: