关系实体具有属性的重复关系

这里有一个可行的解决方案。在我进入细节之前:关键是你坚持什么东西。您应该以一个明确的有界上下文为目标,只访问一个聚合的兴趣。我决定将用户作为事物的入口点。用户有兴趣,应该通过用户添加和操纵兴趣。

OGM和Spring数据Neo4j负责保存从用户传出的关系。

所以要点是:不要每次都保存 NodeEntity 你自己。以隐式方式保存实体之间的关联,即:仅保存父对象。您可以通过会话本身来完成,也可以像我那样,通过存储库来完成。请注意,您不需要为每个实体都提供存储库。

我们有兴趣:

@NodeEntity
public class Interest {
    @Id
    @GeneratedValue
    private Long id;

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

用户感兴趣的是:

@RelationshipEntity(type = UserInterest.TYPE)
public class UserInterest {

    public static final String TYPE = "INTERESTED_IN";

    private Long id;

    @StartNode
    private User start;

    @EndNode
    private Interest end;

    private Long weight;

    public void setStart(User start) {
        this.start = start;
    }

    public Interest getEnd() {
        return end;
    }

    public void setEnd(Interest end) {
        this.end = end;
    }

    public void setWeight(Long weight) {
        this.weight = weight;
    }
}

public class User {
    @Id
    @GeneratedValue
    private Long id;

    private String name;

    @Relationship(type = UserInterest.TYPE, direction = Relationship.OUTGOING)
    private Set<UserInterest> interests = new HashSet<>();

    public void setName(String name) {
        this.name = name;
    }

    public Interest setInterest(String interstName, long weight) {

        final UserInterest userInterest = this.interests.stream()
            .filter(i -> interstName.equalsIgnoreCase(i.getEnd().getName()))
            .findFirst()
            .orElseGet(() -> {
                // Create a new interest for the user
                Interest interest = new Interest();
                interest.setName(interstName);

                // add it here to the interests of this user
                UserInterest newUserInterest = new UserInterest();
                newUserInterest.setStart(this);
                newUserInterest.setEnd(interest);
                this.interests.add(newUserInterest);
                return newUserInterest;
            });
        userInterest.setWeight(weight);
        return userInterest.getEnd();
    }
}

看到了吗 setInterest . 这是使用 User UserInterest ,将其添加到用户兴趣中,最后设置权重,然后返回以供进一步使用。

那么,我宣布 一

public interface UserRepository extends Neo4jRepository<User, Long> {
    Optional<User> findByName(String name);
}

现在是应用程序:

@SpringBootApplication
public class SorelationshipsApplication implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(SorelationshipsApplication.class, args);
    }

    private final UserRepository userRepository;

    private final SessionFactory sessionFactory;

    public SorelationshipsApplication(UserRepository userRepository, SessionFactory sessionFactory) {
        this.userRepository = userRepository;
        this.sessionFactory = sessionFactory;
    }

    @Override
    public void run(String... args) throws Exception {
        Optional<User> optionalUser = this.userRepository
            .findByName("Michael");
        User user;

        ThreadLocalRandom random = ThreadLocalRandom.current();
        if(optionalUser.isPresent()) {

            // Redefine interests and add a new one
            user = optionalUser.get();
            user.setInterest("Family", random.nextLong(100));
            user.setInterest("Bikes", random.nextLong(100));
            user.setInterest("Music", random.nextLong(100));
        } else {
            user = new User();
            user.setName("Michael");

            user.setInterest("Bikes", random.nextLong(100));
            user.setInterest("Music", random.nextLong(100));

        }

        userRepository.save(user);
        // As an alternative, this works as well...
        // sessionFactory.openSession().save(user);
    }
}

这只是一个针对我的本地Neo4j实例运行的命令行示例,但我认为它解释得足够好了。

我检查用户是否存在。如果没有,创建它并添加一些兴趣。在下一次运行时,修改现有的兴趣并创建一个新的兴趣。任何进一步的运行只是修改现有的利益。

ifPresentOrElse 在 Optional

userRepository.findByName("Michael").ifPresentOrElse(existingUser -> {
    existingUser.setInterest("Family", random.nextLong(100));
    existingUser.setInterest("Bikes", random.nextLong(100));
    existingUser.setInterest("Music", random.nextLong(100));
    userRepository.save(existingUser);
}, () -> {
    User user = new User();
    user.setName("Michael");

    user.setInterest("Bikes", random.nextLong(100));
    user.setInterest("Music", random.nextLong(100));
    userRepository.save(user);
});

我希望这有帮助。

编辑:以下是我的依赖项:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>sorelationships</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>sorelationships</name>
    <description>Demo project for Spring Boot</description>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>11</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-neo4j</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>