You have a user database, and want to retrieve users by name. To begin with, this is the structure of the database we want to create:

Figure 4.2. Node space view of users

That is, the reference node is connected to a users-reference node to which all users are connected.

	Tip
	The source code used in this example is found here: EmbeddedNeo4jWithIndexing.java

To begin with, we define the relationship types we want to use:

private static enum RelTypes implements RelationshipType
{
    USERS_REFERENCE,
    USER
}

Then we have created two helper methods to handle user names and adding users to the database:

private static String idToUserName( final int id )
{
    return "user" + id + "@neo4j.org";
}

private static Node createAndIndexUser( final String username )
{
    Node node = graphDb.createNode();
    node.setProperty( USERNAME_KEY, username );
    nodeIndex.add( node, USERNAME_KEY, username );
    return node;
}

The next step is to start the database server:

graphDb = new GraphDatabaseFactory().newEmbeddedDatabase( DB_PATH );
nodeIndex = graphDb.index().forNodes( "nodes" );
registerShutdownHook();

It’s time to add the users:

Transaction tx = graphDb.beginTx();
try
{
    // Create users sub reference node
    Node usersReferenceNode = graphDb.createNode();
    graphDb.getReferenceNode().createRelationshipTo(
        usersReferenceNode, RelTypes.USERS_REFERENCE );
    // Create some users and index their names with the IndexService
    for ( int id = 0; id < 100; id++ )
    {
        Node userNode = createAndIndexUser( idToUserName( id ) );
        usersReferenceNode.createRelationshipTo( userNode,
            RelTypes.USER );
    }

And here’s how to find a user by Id:

int idToFind = 45;
Node foundUser = nodeIndex.get( USERNAME_KEY,
    idToUserName( idToFind ) ).getSingle();
System.out.println( "The username of user " + idToFind + " is "
    + foundUser.getProperty( USERNAME_KEY ) );