neo4j Java初學者。 Cypher執行引擎

用戶在網站上登錄並創建不同的事件。該事件作爲節點保存到neo4j數據庫中，並在用戶和事件節點之間創建「EVENT_CREATOR」實例。neo4j Java初學者。 Cypher執行引擎

我想爲我的網站上的所有用戶事件（使用Play2框架）實現分頁，例如，如果用戶訪問第一頁，我需要加載前10個事件;第2頁加載10th- 20日的事件，等等...

這是我的查詢：

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

在我收到由用戶創建的所有事件的時刻，將它們添加到數組列表。

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; 
}

我要更新的代碼運行的Cypher查詢和我的添加下列代碼行（使用例如https://www.tutorialspoint.com/neo4j/neo4j_cypher_api_example.htm）

GraphDatabaseService db = Neo4JHelper.getDatabase(); 
ExecutionEngine execEngine = new ExecutionEngine(db); //HERE I GET AN ERROR 
ExecutionResult execResult = execEngine.execute("MATCH (n) RETURN n"); 
String results = execResult.dumpToString(); 
System.out.println(results);

它期待一個第二參數：記錄器。什麼是錯誤或有什麼我做錯了？

來源

2017-03-07 Andrew T

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 
     }

看看文檔：

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

來源

2017-03-08 13:45:53 Andrew

neo4j Java初學者。 Cypher執行引擎

回答

相關問題