Question

我有3个类，有User，Role和UserRole。我想获取UserRole的数据，但总是返回NULL。

这是用户类。

@NodeEntity
public class User {
    @GraphId
    Long id;

    @NotNull
    private String username;

    @NotNull
    private String password;

    @NotNull
    private String firstName;

    @NotNull
    private String lastName;

    @NotNull
    private String role;

    @NotNull
    private Boolean active;

    @Relationship(type = "HAS_ROLE", direction = Relationship.OUTGOING)
    private Set<UserRole> userRoles;

    public User() {
        super();
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }

    public Boolean getActive() {
        return active;
    }

    public void setActive(Boolean active) {
        this.active = active;
    }

    public Iterable<UserRole> getUserRoles() {
        return userRoles;
    }

    public void setUserRoles(Set<UserRole> userRoles) {
        this.userRoles = userRoles;
    }
}

这是我的角色等级

@NodeEntity
public class Role {
    @GraphId
    Long id;

    @NotNull
    String name;

    @Relationship(type = "HAS_ROLE",direction = Relationship.OUTGOING)
    @JsonIgnore
    private Set<UserRole> userRoles;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }


    public String getName() {
        return name;
    }

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

    public Set<UserRole> getUserRoles() {
        return userRoles;
    }

    public void setUserRoles(Set<UserRole> userRoles) {
        this.userRoles = userRoles;
    }

    public Role() {
        super();
    }
}

这是我的UserRole Class

@RelationshipEntity(type = "HAS_ROLE")
public class UserRole {
    @GraphId
    Long id;

    @StartNode
    @Relationship(type="HAS_ROLE", direction=Relationship.INCOMING)
    User user;

    @EndNode
    @Relationship(type="HAS_ROLE", direction=Relationship.INCOMING)
    Role role;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    public Role getRole() {
        return role;
    }

    public void setRole(Role role) {
        this.role = role;
    }

    public UserRole(User user, Role role) {
        super();
        this.user = user;
        this.role = role;
    }

    public UserRole() {
        super();
    }
}

我想显示所有用户数据，但结果总是显示userRoles为NULL。我正在使用findAll（1）和findAll（2），但没有什么不同。

它与SDN 3不同，我们只在字段中添加@Fetch。在SDN 4中，没有@Fetch注释。我如何获取所有数据？

UPDATE !!

我像Luanne一样更改了类，并修改了这样的User类：

@NodeEntity
public class User {
    @GraphId
    Long id;

    @NotNull
    private String username;

    @NotNull
    private String password;

    @NotNull
    private String firstName;

    @NotNull
    private String lastName;

    @NotNull
    private String role;

    @NotNull
    private Boolean active;

    @Relationship(type = "HAS_ROLE")
    private Set<UserRole> userRoles;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }

    public Boolean getActive() {
        return active;
    }

    public void setActive(Boolean active) {
        this.active = active;
    }

    @Relationship(type = "HAS_ROLE")
    public Set<UserRole> getUserRoles() {
        return userRoles;
    }

    @Relationship(type = "HAS_ROLE")
    public void setUserRoles(Set<UserRole> userRoles) {
        this.userRoles = userRoles;
    }

    public User(){
        super();
    }
}

保存数据并显示后，角色显示如下：

[{"id":27,"username":"daviduck123","password":"admin","firstName":"David","lastName":"Vincent","role":"admin","active":null,"roles":{"id":"29","name":"ROLE_ADMIN"}}]

但之后我尝试再次显示所有数据，并再次返回NULL，如下所示：

[{"id":27,"username":"daviduck123","password":"admin","firstName":"David","lastName":"Vincent","role":"admin","active":null,"roles":null}]

这是我的资料库https://github.com/daviduck123/neo4j-ogm-infiniteloop

Answer 1

@RelationshipEntity表示两个节点之间的合格关系，因此在其中使用@Relationship是不正确的。

UserRole应该看起来像

@RelationshipEntity(type = "HAS_ROLE")
public class UserRole {
    @GraphId
    Long id;

    @StartNode
    User user;

    @EndNode
    Role role;

由于您要定义Role到HAS_ROLE之间的User关系，因此Role类中的关系方向应该是INCOMING：

    @Relationship(type = "HAS_ROLE",direction = Relationship.INCOMING)
    @JsonIgnore
    private Set<UserRole> userRoles;

   @Relationship(type = "HAS_ROLE",direction = Relationship.INCOMING)    
   public Set<UserRole> getUserRoles() {
        return userRoles;
    }

   @Relationship(type = "HAS_ROLE",direction = Relationship.INCOMING)   
   public void setUserRoles(Set<UserRole> userRoles) {
        this.userRoles = userRoles;
    }

确保访问者和mutator方法也被注释（当你有INCOMING关系时是强制性的。）

Answer 2

我猜Luanne的解决方案可行，我们应该使用它。但我还有另一项工作要做。您可以在存储库中使用@Query来自定义查询。在查询中，您可以返回所需的所有对象并将其记录到地图中。

@Query("match (ac: Address) <-[:at]- (c: Company) <-[:of]- (p: Position) -[:at]-> (a: Address) "
        + "where p.name =~ {0} return p as position, c as company, a as address, ac as companyAddress skip {1} limit {2}")
List<Map<String, Object>> fetchByTitle(String title, int start, int pageSize);

然后，您需要手动设置关系。

List<Position> positions = new ArrayList<Position>();
    for (Map<String, Object> d : data) {
        Position pos = (Position) d.get("position");
        pos.setCompany((Company) d.get("company"));
        pos.setLocation((Address) d.get("address"));
        pos.getCompany().setAddress((Address) d.get("companyAddress"));
        positions.add(pos);
    }

    return positions;

亲们不需要使用@RelationshipEntity，作为一个SQL人员，我仍然不习惯。可以肯定的是，这不是一种自然解决方案。

Spring Data Neo4j 4 - @Fetch更改为findAll（int depth）始终返回null

2 个答案: