= Spring Data Neo4j 4.1.x - Quick start

[source,java]
----
@NodeEntity
class Person {
    private Long id;
    private String name;

    @Relationship(type = "FRIEND", direction = "UNDIRECTED")
    private Set<Person> friends;

    public Person() {}
    public Person(String name) { this.name = name; }

    private void knows(Person friend) { friends.add(friend); }
}

public interface PersonRepository extends GraphRepository<Person> {
}

Person jon = new Person("Jon");
Person emil = new Person("Emil");
Person rod = new Person("Rod");

emil.knows(jon);
emil.knows(rod);

// Persist entities and relationships to graph database
personRepository.save(emil);

for (Person friend : emil.getFriends()) {
    System.out.println("Friend: " + friend);
}

// Control loading depth
jon = personRepository.findOne(id, 2);
for (Person friend : jon.getFriends()) {
    System.out.println("Jon's friends to depth 2: " + friend);
}
----

== About

The primary goal of the http://projects.spring.io/spring-data[Spring Data] project is to make it more convenient and consistent to build Spring-based applications that use modern data technologies.
Spring Data Neo4j integrates the leading http://neo4j.com/[Neo4j] Graph Database.

The Spring Data Neo4j project provides a simplified POJO based programming model that reduces that amount of boilerplate code needed to create Neo4j applications.

It supports:

* automatic mapping annotated domain entities for nodes and relationships
* interface based repositories with provided, derived, and annotated finder methods
* transaction control
* multi-transport (HTTP, Embedded, Bolt)
* exception translation
* integration into Spring Data REST
* works well within Spring Boot

== License

Spring Data Neo4j is licensed under the Apache License v 2.0.
The underlying technology, neo4j-ogm-core, -compiler, -http-driver, -bolt-driver and the neo4j-java-driver are Apache licensed too.

== Using Spring Data Neo4j

=== Maven configuration

* Add the maven repository and dependency:

.pom.xml
[source,xml]
----
<dependencies>
    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-neo4j</artifactId>
        <version>4.1.6</version>
    </dependency>
</dependencies>
----


=== Spring configuration

* Configure Spring Data Neo4j 4.1 in your application using Java-based bean configuration

.MyConfiguration.java
[source,java]
----
@Configuration
@EnableNeo4jRepositories(basePackages = "com.example.person.repository",...)
@EnableTransactionManagement
public class MyConfiguration extends Neo4jConfiguration {

    @Bean
    public SessionFactory getSessionFactory() {
        // with domain entity base package(s)
        return new SessionFactory("com.example.person.domain",...);
    }

    // needed for session in view in web-applications
    @Bean
    @Scope(value = "session", proxyMode = ScopedProxyMode.TARGET_CLASS)
    public Session getSession() throws Exception {
        return super.getSession();
    }

}
----

Spring Data Neo4j 4.1 provides support for connecting to Neo4j using different drivers.
HTTP, Embedded and Bolt drivers are available.
Spring Data Neo4j will attempt to auto-configure itself using a file called `ogm.properties`, which it expects to find on the classpath.

.ogm.properties
[source,java]
----
driver=org.neo4j.ogm.drivers.http.driver.HttpDriver
URI=http://user:password@localhost:7474
----

The application can be configured programmatically as well, please http://docs.spring.io/spring-data/data-neo4j/docs/current/reference/html/#_spring_configuration[read the reference guide] for more information.

=== Graph entities

* Annotate your entity class.  In this case it is a 'Person' class that has a relationship to the 'Company' they work at :

[source,java]
----
package com.example.person.domain;

@NodeEntity
class Person {
    private Long id;
    private String name;

    @Relationship(type = "WORKS_AT", direction = "OUTGOING")
    private Company employer;

    public Person() {}
    public Person(String name) { this.name = name; }

    private void worksAt(Company employer) { this.employer = employer; }
}
----

=== Transactional services

Create a repository or service to perform typical operations on your entities.
The complete functionality is covered in the http://docs.spring.io/spring-data/data-neo4j/docs/current/reference/html/#reference_programming-model[reference manual]

[source,java]
----
package com.example.person.repository;

public interface PersonRepository extends GraphRepository<Person> {

   // derived finder method
   Person findByName(String name);

   @Query("MATCH (c:Company)<-[:WORKS_AT]-(p:Person) WHERE id(c) = {company} RETURN p")
   List<Person> findEmployees(Company company);
}

package com.example.person.service;

@Service
@Transactional
public class EmployeeService {

    @Autowired
    private PersonRepository personRepository;

    public int getNumberOfPeople() {
        return personRepository.count();
    }

    public Person createPerson(String name) {
        return personRepository.save(new Person(name));
    }

    public List<Person> getAllPeople() {
        return personRepository.findAll();
    }

    public List<Person> getEmployees(Company c) {
        return personRepository.findEmployees(c);
    }
}
----

Please see the https://github.com/neo4j-examples/sdn4-university/tree/4.1[SDN University sample project] for more information.

More example projects for Spring Data Neo4j 4 are available in the https://github.com/neo4j-examples?query=sdn4[Neo4j-Examples] repository

== Getting Help

This README and the http://static.springsource.org/spring-data/data-neo4j/docs/current/reference/html/[Reference Manual] are the best places to start learning about Spring Data Neo4j 4.

The main http://projects.spring.io/spring-data-neo4j[SpringSource project site] contains links to basic project information such as source code, JavaDocs, Issue tracking, etc.

For more detailed questions, use the "forum":http://forum.springsource.org/forumdisplay.php?f=80. If you are new to Spring as well as to Spring Data, look for information about "Spring projects":http://www.springsource.org/projects.


You will also find help on http://stackoverflow.com/questions/tagged/spring-data-neo4j[StackOverflow]

== Contributing to Spring Data Neo4j

There are dedicated, mandatory https://github.com/spring-projects/spring-data-build/blob/master/CONTRIBUTING.adoc[contribution guidelines] for all Spring Data projects.

Here are some ways for you to get involved in the community:

* Get involved with Spring Data Neo4j community on the http://groups.google.com/group/neo4j[Neo4j Google Group] and by helping on http://stackoverflow.com/questions/tagged/spring-data-neo4j[StackOverflow].
* Create https://jira.springframework.org/browse/DATAGRAPH[JIRA] tickets for bugs and new features and comment and vote on the ones that you are interested in.
* Github is for social coding: if you want to write code, we encourage contributions through *pull requests* from a fork of this repository.
  If you want to contribute code this way, please read the https://github.com/spring-projects/spring-data-build/blob/master/CONTRIBUTING.adoc[contribution guidelines] for details.