java - Spring 和neo4j : Previous relationships are deleted when adding new ones

Question

这是我的用户类:

@NodeEntity
public class User {

    @GraphId
    private Long id;

    @Property
    private String name;

    @Property
    private String email;

    @Property
    private String password;

    @Property
    private String photoLink;

    @Property
    private Integer age;

    @Property
    private Country country;

    @Property
    private Gender gender;

    @Property
    private String about;

    @Property
    private boolean online;

    private Collection<UserHasLanguage> hasLanguage;

    @Relationship(type="HAS_ROLE", direction=Relationship.OUTGOING)
    private Collection<Role> roles;

    @Relationship(type="HAS_IN_FRIENDLIST", direction=Relationship.OUTGOING)
    private Collection<User> friendList;

    @Relationship(type="HAS_IN_BLACKLIST", direction=Relationship.OUTGOING)
    private Collection<User> blackList;

因此，我希望用户与其他用户建立单方关系 HAS_IN_FRIENDLIST。在服务级别，我有一种向用户添加 friend 的方法:

public void addToFriendList (User whoAdds, User whoIsAdded)
        throws UserNotFoundException{
    if (whoIsAdded == null)
        throw new UserNotFoundException("User not found");
    Collection<User> friendList = whoAdds.getFriendList();
    if (friendList == null)
        friendList = new HashSet<>();
    friendList.add(whoIsAdded);
    whoAdds.setFriendList(friendList);
    userRepository.save(whoAdds);
}

但是，当我使用此方法时，该用户以前的一些关系“HAS_IN_FRIENDLIST”被删除。我注意到，whoAdds.getFriendList() 方法始终仅返回 1 个用户。

我该如何解决这个问题？

Answer 1

我无法对此进行测试，但我的理解是不支持 Collection。对于列表，您必须使用其中之一(如指定 here )

java.util.Vector

java.util.List，由 java.util.ArrayList 支持

java.util.SortedSet，由 java.util.TreeSet 支持

java.util.Set，由 java.util.HashSet 支持

数组

所以改变<code>Collection<User></code>至<code>Set<User></code>