Question

我有一个奇怪的问题，我可以使用createRelationshipTo（）方法在嵌入式neo4j中创建关系。但是，当我使用getRelationships（）方法访问这些关系时，找不到任何关系。当我创建关系并立即使用getRelationships（）方法时，找到该关系。但是后来，这种关系就失去了。

E.g。在sampleMethod（）中，我在同一个方法中创建和检索关系，因此它返回两个关系，但是当我尝试使用sampleMethod2（）中相同的getRelationships（）方法检索相同的关系时，它什么都没有。

public ArrayList<String> sampleMethod() {
        ArrayList<String>list = new ArrayList<String>();
        DatabaseConnection dbConnection = new DatabaseConnection();
        GraphDatabaseService graphDb = dbConnection.connectToDatabase();
        Transaction tx = graphDb.beginTx();

        Node user = graphDb.findNode(Label.label("User"), "userName", "hamna123");
        Node restaurant = graphDb.findNode(Label.label("Restaurants"), "name", "The Grand Regency");
        Relationship rel = user.createRelationshipTo(restaurant, RelationshipType.withName("Visited"));
                    Relationship rel2 = user.createRelationshipTo(restaurant, RelationshipType.withName("Favorite"));
        for (Relationship relationship : user.getRelationships()) {
            String found = relationship.getType().name().toString();
            list.add(found);
        }
        tx.close();
        //graphDb.shutdown();
        return list;

    }

public ArrayList<String> sampleMethod2() {
        ArrayList<String>list = new ArrayList<String>();
        DatabaseConnection dbConnection = new DatabaseConnection();
        GraphDatabaseService graphDb = dbConnection.connectToDatabase();
        Transaction tx = graphDb.beginTx();
        Node user = graphDb.findNode(Label.label("User"), "userName", "hamna123");
                Iterable<Relationship> relations = user.getRelationships();
        for (Relationship relationship : relations) {
            String found = relationship.getType().name().toString();
            list.add(found);
        }
        tx.close();
        graphDb.shutdown();
        return list;

    }

Answer 1

不要在没有提交的情况下关闭交易。否则，将执行回滚。

所以：

使用catch-with-resource模式关闭交易
在代码末尾将tx设为成功

示例：

try ( Transaction tx = db.beginTx())
{
    Node myNode = db.createNode();
    myNode.setProperty( "name", "my node" );
    tx.success(); // commit the tx
}

关系已创建但未存储在嵌入式neo4j中

1 个答案: