Question

用户登录网站并创建不同的活动。此事件作为节点保存到neo4j数据库中，然后生成＆＃34; EVENT_CREATOR＆＃34;用户和事件节点之间的关系。

我正在尝试为我网站上的所有用户事件（使用Play2框架）实现分页，例如，如果用户访问第一页，我需要加载前十个事件;加载第10至第20个事件的第2页，依此类推......

这是我的疑问：

apache

目前，我正在获取用户创建的所有事件，并将它们添加到数组列表中。

match(n);
...
skip k;
limit 10;
return n;

我想更新代码以运行Cypher查询，并添加以下代码行（使用示例https://www.tutorialspoint.com/neo4j/neo4j_cypher_api_example.htm）

private static List<PublicEvent> getEvents(int page, int pageSize) {

    List<PublicEvent> events = new ArrayList<PublicEvent>();

    GraphDatabaseService db = Neo4JHelper.getDatabase();
    try (Transaction tx = db.beginTx()) {

        Index<Node> userIndex = db.index().forNodes(ModelIndex.Users);

        IndexHits<Node> userNodes = userIndex.get(ModelGraphProperty.UserProfile.UserName, SessionUtilities.getCurrentUser());
        Node me = userNodes.next(); //current logged in user

        PagingIterator paginator = new PagingIterator(me.getRelationships(GraphRelation.RelTypes.EVENT_CREATOR).iterator(), pageSize); // get all the events that were created by this user
        paginator.page(page);

        // adding all the created events by this user to an array
        if (paginator.hasNext()) {
            Relationship eventCreator = (Relationship)paginator.next();
            Node event = eventCreator.getOtherNode(me);
            events.add(new PublicEvent(event));
        }

        tx.success();
    }

    db.shutdown();

    return events;
}

期待第二个参数：记录器。什么是错误或者我做错了什么？

Answer 1

  RestGraphDatabase db= (RestGraphDatabase)Neo4JHelper.getDatabase();
        RestCypherQueryEngine engine=new RestCypherQueryEngine(db.getRestAPI());
        Map<String, Object> params = new HashMap<String, Object>();
        params.put( "id", eventId );
        String query="match (s) where id(s) = {id} return s;";
        QueryResult result=engine.query(query,params);

        if(result.iterator().hasNext()) {

           //HERE PUT WHATEVER YOU NEED
        }

看一下文档：

https://neo4j.com/docs/java-reference/current/

neo4j Java初学者。 Cypher执行引擎

1 个答案: