SDN4 总是返回一个关系，即使 neo4j 有多个关系

Question

我有两个实体 Person 和 Building。两者由两个关系实体"PERSON_HAS_ACCESS"（多人可以访问多个建筑物）和"PERSON_OWNS"（一个建筑物只能由一个人拥有，但一个人可以拥有多个建筑物）相关。我能够坚持每种类型的不止一种关系（具体来说是 2 种），并且也可以在 neo4j 浏览器中看到。但是，当我使用会话 API:

访问 Person 实体时

  session.loadAll(klazz, new Filter("uuid", uuid), 1).getAccessRelations.size()

总是返回 1，不管它有多少关系。

我总是只得到一种关系。

这是我的领域模型。我添加了 equals 和哈希码，但问题仍然存在。此外，我尝试过只有一种关系，但问题还是一样。这让我疯狂！！。任何帮助将不胜感激。

@NodeEntity
public class Building {
    @GraphId
    private Long id;

    private String uuid;

    @Relationship(type = "PERSON_OWNS", direction = Relationship.INCOMING)
    private OwnsBuilding ownsRelation;

    @Relationship(type = "PERSON_HAS_ACCESS", direction = Relationship.INCOMING)
    private Collection<CanAccess> accessRelations = new HashSet<CanAccess>();

    public Collection<CanAccess> getAccessRelations() {
    return accessRelations;
    }

    public Building setAccessRelations(Collection<CanAccess> accessRelations) {
    this.accessRelations = accessRelations;
    return this;
    }

    public String getUuid() {
    return uuid;
    }

    public Building setUuid(String uuid) {
    this.uuid = uuid;
    return this;
    }

    public OwnsBuilding getOwnsRelation() {
    return ownsRelation;
    }

    public Building setOwnsRelation(OwnsBuilding ownsRelation) {
    this.ownsRelation = ownsRelation;
    return this;
    }

    @Override
    public boolean equals(Object obj) {
    if (obj == null || !(obj instanceof Building)) return false;
    if(id == null) return false;
    return obj == this || this.id.equals(((Building) obj).id);
    }

    @Override
    public int hashCode() {
    return id != null ? id.hashCode() : super.hashCode();
    }
}


@NodeEntity
public class Person {

    private String uuid;

    @GraphId
    private Long id;

    @Relationship(type = "PERSON_HAS_ACCESS", direction = Relationship.OUTGOING)
    private Collection<CanAccess> accessRelations = new HashSet<CanAccess>();

    @Relationship(type = "PERSON_OWNS", direction = Relationship.OUTGOING)
    private Collection<OwnsBuilding> ownsRelations = new HashSet<OwnsBuilding>();

    public Collection<CanAccess> getAccessRelations() {
    return accessRelations;
    }

    public Person setAccessRelations(Collection<CanAccess> accessRelations) {
    this.accessRelations = accessRelations;
    return this;
    }

    public String getUuid() {
    return uuid;
    }

    public Person setUuid(String uuid) {
    this.uuid = uuid;
    return this;
    }

    public Collection<OwnsBuilding> getOwnsRelations() {
    return ownsRelations;
    }

    public Person setOwnsRelations(Collection<OwnsBuilding> ownsRelations) {
    this.ownsRelations = ownsRelations;
    return this;
    }

    @Override
    public boolean equals(Object obj) {
    if (obj == null || !(obj instanceof Person)) return false;
    if (id == null) return false;
    return obj == this || this.id.equals(((Person) obj).id);
    }

    @Override
    public int hashCode() {
    return id != null ? id.hashCode() : super.hashCode();
    }
}


@RelationshipEntity(type = "PERSON_HAS_ACCESS")
public class CanAccess {
    @GraphId
    private Long id;

    @StartNode
    private Person person;

    public CanAccess(){}

    public CanAccess(Person person, Building building) {
    this.person = person;
    this.building = building;
    }

    @EndNode
    private Building building;

    public Person getPerson() {
    return person;
    }

    public CanAccess setPerson(Person person) {
    this.person = person;
    return this;
    }

    public Building getBuilding() {
    return building;
    }

    public CanAccess setBuilding(Building building) {
    this.building = building;
    return this;
    }

    @Override
    public boolean equals(Object obj) {
    if (obj == null || !(obj instanceof CanAccess)) return false;
    if (id == null) return false;
    return obj == this || this.id.equals(((CanAccess) obj).id);
    }

    @Override
    public int hashCode() {
    return id != null ? id.hashCode() : super.hashCode();
    }
}


@RelationshipEntity(type = "PERSON_OWNS")
public class OwnsBuilding {
    @GraphId
    private Long id;

    public OwnsBuilding() {
    }

    public OwnsBuilding(Person owner, Building building) {
    this.owner = owner;
    this.building = building;
    }

    @StartNode

    private Person owner;

    @EndNode
    private Building building;

    public Person getOwner() {
    return owner;
    }

    public OwnsBuilding setOwner(Person owner) {
    this.owner = owner;
    return this;
    }

    public Building getBuilding() {
    return building;
    }

    public OwnsBuilding setBuilding(Building building) {
    this.building = building;
    return this;
    }

    @Override
    public boolean equals(Object obj) {
    if (obj == null || !(obj instanceof OwnsBuilding)) return false;
    if (id == null) return false;
    return obj == this || this.id.equals(((OwnsBuilding) obj).id);
    }

    @Override
    public int hashCode() {
    return id != null ? id.hashCode() : super.hashCode();
    }
}

Answer 1

请将您的 Collection 更改为 Set -

 @Relationship(type = "PERSON_HAS_ACCESS", direction = Relationship.INCOMING)
 private Collection<CanAccess> accessRelations = new HashSet<CanAccess>();

至

 @Relationship(type = "PERSON_HAS_ACCESS", direction = Relationship.INCOMING)
 private Set<CanAccess> accessRelations = new HashSet<CanAccess>();

OGM 可以创建数组或 Set,List,Vector.

此外，尽管与问题无关，但请确保当您的关系方向是 INCOMING 时，您明确注释任何 properties/accessors/mutators。在你的情况下：

@Relationship(type = "PERSON_HAS_ACCESS", direction = Relationship.INCOMING)
private Set<CanAccess> accessRelations = new HashSet<CanAccess>();

@Relationship(type = "PERSON_HAS_ACCESS", direction = Relationship.INCOMING)
public Set<CanAccess> getAccessRelations() {...}

@Relationship(type = "PERSON_HAS_ACCESS", direction = Relationship.INCOMING)
public Building setAccessRelations(Set<CanAccess> accessRelations) {...}

另一个是 make sure your object model is navigable 特别是在关系实体的情况下。当你创建关系实体时，记得在参与节点上设置它，例如

public CanAccess(Person person, Building building) {
    this.person = person;
    this.building = building;
    this.person.getAccessRelations().add(this);
    this.building.getAccessRelations().add(this);
}

SDN4 总是返回一个关系，即使 neo4j 有多个关系

SDN4 is always returning one relationship even though neo4j has multiple relationships

entity-framework

neo4j

spring-data-neo4j-4