Brings up a Neo4jGraphQL Java server.

Neo4jGraphqlJava.java

///usr/bin/env jbang "$0" "$@" ; exit $?
//JAVA 16
//JAVAC_OPTIONS -source 16
//DEPS info.picocli:picocli:4.6.1
//DEPS io.javalin:javalin:3.13.9
//DEPS org.neo4j.driver:neo4j-java-driver:4.3.3
//DEPS org.neo4j:neo4j-graphql-java:1.3.0
//DEPS com.fasterxml.jackson.core:jackson-databind:2.10.5
//DEPS org.slf4j:slf4j-simple:1.7.31
package com.example.graphqlplain;

import io.javalin.Javalin;
import picocli.CommandLine;

import java.io.File;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.nio.file.Files;

import org.neo4j.driver.AuthTokens;
import org.neo4j.driver.Config;
import org.neo4j.driver.GraphDatabase;
import org.neo4j.driver.Logging;
import org.neo4j.driver.Record;
import org.neo4j.graphql.SchemaBuilder;
import org.neo4j.graphql.Translator;

/**
 * Run with {@code jbang Neo4jGraphqlJava.java}
 * to bring up a Neo4j GraphQL Java server connected against your local instance with a default schema.
 *
 * Run {@code jbang Neo4jGraphqlJava.java --help} to print available options.
 *
 * @author Michael Simons
 */
@CommandLine.Command(name = "neo4j-graphql", mixinStandardHelpOptions = true,
	description = "Starts a Neo4j-Graphql middleware.")
public class Neo4jGraphqlJava implements Runnable {

	@CommandLine.Option(names = { "-u", "--user" }, description = "Neo4j user", defaultValue = "neo4j")
	String user;

	@CommandLine.Option(names = { "-p",
		"--password" }, description = "Neo4j password", arity = "0..1", interactive = true, defaultValue = "secret")
	char[] password;

	@CommandLine.Option(names = { "-a",
		"--address" }, description = "address and port to connect to", defaultValue = "neo4j://localhost:7687")
	String address;

	@CommandLine.Option(names = { "-P", "--port" }, description = "Port to listen on", defaultValue = "7000")
	Integer port;

	@CommandLine.Option(names = "--schema", arity = "0..1", description = "Schema definition")
	File schema;

	public static void main(String[] args) {

		new CommandLine(new Neo4jGraphqlJava()).execute(args);
	}

	private String getSchema() {

		if (this.schema != null) {
			try {
				return Files.readString(this.schema.toPath());
			} catch (IOException e) {
				throw new UncheckedIOException(e);
			}
		} else {
			return """
				type Person {
					name: ID!
					born: Int
					actedIn: [Movie] @relation(name: "ACTED_IN")
				}

				type Movie {
					title: ID!
					released: Int
					tagline: String
				}

				type Query {
					person: [Person]
				}
				""";
		}
	}

	@Override
	public void run() {

		var driver = GraphDatabase.driver(
			address,
			AuthTokens.basic(user, new String(this.password)),
			Config.builder().withLogging(Logging.slf4j()).build()
		);
		driver.verifyConnectivity();

		var graphql = new Translator(SchemaBuilder.buildSchema(getSchema()));

		var server = Javalin.create()
			.events(event -> event.serverStopping(() -> driver.close()))
			.start(port);

		server.post("/graphql", ctx -> {
			if (ctx.contentLength() == 0) {
				return;
			}
			graphql.translate(ctx.body()).stream().findFirst().ifPresent(cypher -> {
				try (var session = driver.session()) {
					var result = session
						.writeTransaction(tx -> tx.run(cypher.getQuery(), cypher.getParams()).list(Record::asMap));
					ctx.json(result);
				}
			});
		});
	}
}