Getting the Most From Today's Java Tooling With Neo4j

© 2022 Neo4j, Inc. All rights reserved.
Getting the Most from Today’s
Java Tooling With Neo4j
Gerrit Meier,
Staff Software Engineer (SDN/OGM)

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3
Neo4j Java Driver
Let’s connect

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1
<dependency>
<groupId>org.neo4j.driver</groupId>
<artifactId>neo4j-java-driver</artifactId>
<version>4.4.5</version>
</dependency

5
1
<dependency>
</dependency
2
var driver = GraphDatabase
.driver("neo4j://host:port",
AuthTokens.basic("neo4j", "secret")
);

6
1
<dependency>
</dependency
2
);
3
var records = session
.run("MATCH (m:Movie) return m")
.list();

7
1
<dependency>
</dependency
2
);
3 4
.list();
.run(
"MATCH (m:Movie) WHERE m.title = $title
return m",
Map.of("title", "The Matrix"))
.list();

8
{
tagline=Welcome to …,
title=The Matrix,
released=1999
}
class Movie {
String title;
}

9
5
{
title=The Matrix,
released=1999
}
class Movie {
String title;
}
var movies = session
.list(record -> {
var movieNode = record.get("m").asNode();
var title = movieNode.get("title")
.asString();
return new Movie(title);
});
System.out.println(movies);
// [Movie{title='The Matrix'}, ...]

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6

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Object Graph Mapping
Sync the Graphs

13
{
title=The Matrix,
released=1999
}
class Movie {
String title;
}

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{
title=The Matrix,
released=1999
}
class Movie {
String title;
}
1
12
7

15
2a
2b
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-neo4j</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-neo4j</artifactId>
</dependency>

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3
@Node
public class Movie {
@Id
public final String title;
public Movie(String title) {
this.title = title;
}
}

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3 4
@Node
@Id
public final String title;
public Movie(String title) {
this.title = title;
}
}
@Node("Person")
public class Actor {
@Id
public final String name;
@Relationship("ACTED_IN")
public final List<Movie> movies;
public Actor(String name,
List<Movie> movies) {
this.name = name;
this.movies = movies;
}
}

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5
interface ActorRepository extends Neo4jRepository<Actor, String> {}

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5
6
interface ActorRepository extends Neo4jRepository<Actor, String> {}
Actor actor = repository.findById("Tom Hanks").get();
System.out.println(actor);
// Actor{name='Tom Hanks',
// movies=[
// Movie{title='Apollo 13'},
// Movie{title='You've Got Mail'},
// ..]

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7
<dependency>
<groupId>org.neo4j</groupId>
<artifactId>neo4j-ogm-core</artifactId>
</dependency>

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8 9
@NodeEntity("Person")
public class Actor {
@Id
public String name;
@Relationship("ACTED_IN")
public List<Movie> movies;
}
@NodeEntity
@Id
public String title;
}

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10
var sessionFactory = new SessionFactory(
new Configuration.Builder()
.uri("neo4j://localhost:7687")
.credentials("neo4j", "secret")
.build(),
"domainPackage");

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10 11
var sessionFactory = new SessionFactory(
new Configuration.Builder()
.uri("neo4j://localhost:7687")
.credentials("neo4j", "secret")
.build(),
"domainPackage");
var session = sessionFactory.openSession();
var tomHanks =
session.queryForObject(Actor.class,
"MATCH (p:Person)-[r:ACTED_IN]->(m:Movie)
WHERE p.name = $name
return p, collect(r), collect(m)",
Map.of("name", "Tom Hanks"));
System.out.println(tomHanks);
// Actor{
// name='Tom Hanks',
// movies=[
// Movie{title='Apollo 13'},
// Movie{title='The Polar Express'},
// ...
// ]}

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12
quarkus.neo4j.uri=neo4j://localhost:7687
quarkus.neo4j.authentication.username=neo4j
quarkus.neo4j.authentication.password=secret
org.neo4j.ogm.base-packages=
com.meistermeier.graphconnect2022.domain
<dependency>
</dependency>

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13
@Inject
SessionFactory sessionFactory;
@GET
@Produces(MediaType.TEXT_PLAIN)
public String hello() {
var session = sessionFactory.openSession();
var tomHanks = session.queryForObject(
Actor.class,
"MATCH (p:Person)...",
Map.of("name", "Tom Hanks"));
return tomHanks.name;
}
➜ ~ curl http://localhost:8080/hello
Tom Hanks%
12
quarkus.neo4j.uri=neo4j://localhost:7687
quarkus.neo4j.authentication.username=neo4j
quarkus.neo4j.authentication.password=secret
org.neo4j.ogm.base-packages=
com.meistermeier.graphconnect2022.domain
<dependency>
</dependency>

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14

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14
15

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Cypher-DSL
Writing Cypher in a type-safe way

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MATCH
CREATE
MERGE
WHERE n.name=$name
CALL
RETURN n{...}

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1
<dependency>
<artifactId>neo4j-cypher-dsl</artifactId>
</dependency>

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1 2
var query; = "MATCH
(p:Person)-[r:ACTED_IN]->(m:Movie) WHERE
p.name = $name return p, collect(r),
collect(m)";
<dependency>
</dependency>

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1 2
var query; = "MATCH
collect(m)";
<dependency>
</dependency>

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1 2
var query; = "MATCH
collect(m)";
<dependency>
</dependency>
3
Cypher.node("Person").named("p")
Cypher.node("Movie").named("m")

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4 var personNode = Cypher.node("Person").named("p");
var movieNode = Cypher.node("Movie").named("m");
var actedIn = personNode.relationshipTo(movieNode).named("r");
var condition = personNode.property("name").eq(Cypher.parameter("name"));
Cypher.match(actedIn).where(condition).returning(
personNode.as("person"),
Functions.collect(movieNode).as("movies"),
Functions.collect(actedIn).as("relationships"));

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4
5
var personNode = Cypher.node("Person").named("p");
var movieNode = Cypher.node("Movie").named("m");
var actedIn = personNode.relationshipTo(movieNode).named("r");
var condition = personNode.property("name").eq(Cypher.parameter("name"));
Cypher.match(actedIn).where(condition).returning(
personNode.as("person"),
Functions.collect(movieNode).as("movies"),
Functions.collect(actedIn).as("relationships"));
var renderedStatement = Renderer.getDefaultRenderer().render(statement);
System.out.println(renderedStatement);
// MATCH (p:`Person`)-[r]->(m:`Movie`)
// WHERE p.name = $name
// RETURN p AS person,
// collect(m) AS movies,
// collect(r) AS relationships

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Neo4j-Migrations
Friends do let friends write upgrade scripts

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38
1
12
9
7

39
1
<dependency>
<groupId>eu.michael-simons.neo4j</groupId>
<artifactId>neo4j-migrations</artifactId>
</dependency>

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1 2
<dependency>
</dependency>
// V001__InitialImport.cypher
CREATE (:Movie{title: 'The Matrix'});

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1 2
3
<dependency>
</dependency>
var config = MigrationsConfig.defaultConfig();
var migrations = new Migrations(config,
driver);
migrations.apply()

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1 2
4
<dependency>
</dependency>
3
var config = MigrationsConfig.defaultConfig();
var migrations = new Migrations(config,
driver);
migrations.apply()

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5
public class V002__InitialImport implements JavaBasedMigration {
@Override
public void apply(MigrationContext context) {
try (Session session = context.getSession()) {
session.run("CREATE (m:Movie{title:'The Matrix'})").consume();
}
}
}

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5
public class V002__InitialImport implements JavaBasedMigration {
@Override
public void apply(MigrationContext context) {
try (Session session = context.getSession()) {
session.run("CREATE (m:Movie{title:'The Matrix'})").consume();
}
}
}
6

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7
8
<dependency>
<artifactId>neo4j-migrations-spring-boot-starter</artifactId>
</dependency>
org.neo4j.migrations.packages-to-scan=com.meistermeier.graphconnect2022

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9
10
org.neo4j.migrations.packages-to-scan=com.meistermeier.graphconnect2022
<dependency>
<artifactId>neo4j-migrations-quarkus</artifactId>
</dependency>

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11

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12
sdk install neo4jmigrations
jbang neo4j-migrations@neo4j

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12 13
neo4j-migrations
--username=neo4j
--password=secret
--location=file:<..>
apply

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12 13
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neo4j-migrations
--username=neo4j
--password=secret
--location=file:<..>
apply
Applied migration 001
("InitDatabase").
Database migrated to version 001.

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…and many more
1 3
Testcontainers
Neo4j
Liquibase
Neo4j Plugin
2Neo4j GraphQL
Java

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All the links
Spring Data Neo4j https://github.com/spring-projects/spring-data-neo4j/
CypherDSL https://github.com/neo4j-contrib/cypher-dsl
Neo4j-Migrations https://github.com/michael-simons/neo4j-migrations
Developer Guides https://neo4j.com/developer/language-guides/

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IDEA-INSTRUCTIONS.COM
CC by-nc-sa 4.0 Sebastian Morr

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Thank you!
twitter.com/meistermeier
github.com/meistermeier

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