英文:
Transaction close/commit issue in Neo4j Java
问题
我是新来的Neo4j用户。我正在使用Neo4j数据库编写一个Java程序，遇到了在创建节点时遇到的问题。
我在创建新节点时使用了一个事务，然后我想打印它的ID，使用 node.getProperty(ID)。但是我收到了如下所示的错误消息。所以我的问题是，在Java中使用事务时，我们应该在什么时候创建、提交/关闭事务？在创建或搜索节点时，我们是否需要每次都创建一个新事务并进行提交/关闭呢？
Exception in thread "main" org.neo4j.graphdb.NotInTransactionException: 事务已关闭。
at org.neo4j.kernel.impl.coreapi.TransactionImpl.checkInTransaction(TransactionImpl.java:695)
at org.neo4j.kernel.impl.coreapi.TransactionImpl.kernelTransaction(TransactionImpl.java:576)
at org.neo4j.kernel.impl.core.NodeEntity.getProperty(NodeEntity.java:428)
更新：我最初的事务代码是这样的
Node n;
try(Transaction tx = graphDB.beginTx()){
n = tx.createNode(label);
n.setProperty(PROPERTY,value);
tx.commit();
}
System.out.println(n.getProperty(PROPERTY));
现在我将打印语句移到了try子句中，以便它在同一个事务中。
英文:
I'm new to Neo4j. I'm writing a java program using Neo4j database, and I met an issue when I create a node.
I use one transaction for creating the new node, and then I want to print its id, using node.getProperty(ID). But I got error message as attached below. So my question is, when using transaction in java, when should we create and commit/close it? Do we need to create a new transaction and commit/close it each time when creating or searching a node?
Exception in thread "main" org.neo4j.graphdb.NotInTransactionException: The transaction has been closed.
at org.neo4j.kernel.impl.coreapi.TransactionImpl.checkInTransaction(TransactionImpl.java:695)
at org.neo4j.kernel.impl.coreapi.TransactionImpl.kernelTransaction(TransactionImpl.java:576)
at org.neo4j.kernel.impl.core.NodeEntity.getProperty(NodeEntity.java:428)
Update: My original transaction code is like this
Node n;
try(Transaction tx = graphDB.beginTx(){
n = tx.createNode(label);
n.setProperty(PROPERTY,value);
tx.commit();
}
System.out.println(n.getProperty(PROPERTY));
Now I moved the print line to the try clause so it's in the same transaction.
答案1
得分: 1
由交易提供的Node对象仅在交易生命周期内有效。如果您希望在交易之外使用节点属性的值，应在交易期间获取该值并将其存储在适当的位置。
英文:
A Node object provided by a transaction is only valid for the life of the transaction. If you want to use the value of a node property outside of the transaction, you should get the value and store it someplace suitable during the transaction.
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