Michal Bachman bachmanm

CEO at GraphAware

bachmanm / neo4j-tx-event-handler-101.java

Last active March 19, 2020 13:17

An example of a Neo4j transaction event handler (for a blog post)

	@Test
	public void showSimpleEventHandling() {
	GraphDatabaseService database = new TestGraphDatabaseFactory().newImpermanentDatabase();

	database.registerTransactionEventHandler(new TransactionEventHandler<Void>() {
	@Override
	public Void beforeCommit(TransactionData data) throws Exception {
	System.out.println("Committing transaction");
	return null;
	}

bachmanm / neo4j-tx-event-handling-failed.java

Last active December 21, 2015 06:29

A failed attempt to log each about-to-be-deleted node and its properties in Neo4j (for a blog post)

	@Test(expected = TransactionFailureException.class)
	public void attemptLoggingDeletedNodes() {
	GraphDatabaseService database = new TestGraphDatabaseFactory().newImpermanentDatabase();

	database.registerTransactionEventHandler(new TransactionEventHandler.Adapter<Void>() {
	@Override
	public Void beforeCommit(TransactionData data) throws Exception {
	for (Node deletedNode : data.deletedNodes()) {
	StringBuilder message = new StringBuilder("About to delete node ID ")
	.append(deletedNode.getId())

bachmanm / ImprovedTransactionData.java

Created September 26, 2013 16:02

ImprovedTransactionData with methods for nodes only, JavaDoc ommitted

	public interface ImprovedTransactionData {

	boolean hasBeenCreated(Node node);
	Collection<Node> getAllCreatedNodes();

	boolean hasBeenDeleted(Node node);
	Node getDeleted(Node node);
	Collection<Node> getAllDeletedNodes();

	boolean hasBeenChanged(Node node);