Build and run

This is a super insecure Neo4j extension that provides one stored procedure:

name	signature	description
scripts.execute	scripts.execute(scriptUrl :: STRING?) :: VOID	scripts.execute(scriptUrl) - Executes the script at the given URL if accessible. Throws things otherwise.

To run this in the most efficient way, we expect Neo4j to be run on GraalVM for Java 11 and have the necessary dependencies in the provided scope like this:

<dependency>
    <groupId>org.graalvm.sdk</groupId>
    <artifactId>graal-sdk</artifactId>
    <version>${graalvm.version}</version>
    <scope>provided</scope>
</dependency>
<dependency>
    <groupId>org.graalvm.js</groupId>
    <artifactId>js</artifactId>
    <version>${graalvm.version}</version>
    <scope>provided</scope>
</dependency>

If you want to use a standard JDK to run Neo4j, remove the scope and include both dependencies. However, the JAR will be significantly bigger and probably slower.

The extension itself can be build on a plain JDK 11:

mvn clean package

is enough.

A script like this

const collectors = Java.type('java.util.stream.Collectors')

function findConnections(to) { 
    const query = `
        MATCH (:Person {name:$name})-[:ACTED_IN]->(m)<-[:ACTED_IN]-(coActor)
        RETURN DISTINCT coActor`
    
    const db = Polyglot.import("db")
    const tx = db.beginTx()
    
    const names = tx.execute(query, {name: to})
        .stream()
        .map(r => r.get('coActor').getProperty('name'))
        .collect(collectors.toList())    
    tx.close()
    
    return names
} 

names = findConnections('Tom Hanks')
names.forEach(name => console.log(name))

Can be run as

CALL scripts.execute('file:///path/to/script.js')

The important piece in the listing above is the following access to a function provided by GraalVMs polyglot context:

const db = Polyglot.import("db")

it retrieves the Neo4j org.neo4j.graphdb.GraphDatabaseService.

This is a proxy to the Java object of the given class and can be used to execute Cypher or find Nodes and relationships directly. Let your imagination go wild what you can do without apart from printing out stuff.