spring-data-neo4j 自身关系的 REST 结果深度过多答案

【问题标题】：Too many depths in REST result for self relationship of spring-data-neo4jspring-data-neo4j 自身关系的 REST 结果深度过多
【发布时间】：2016-07-08 17:10:04
【问题描述】：

我有一个自我关系（一个员工可以向一个经理汇报，一个经理可能有很多员工）如下：

@NodeEntity
public class Employee {

    @GraphId
    private Long id;

    private String name;
    private String sn;
    private String mail;

    public Employee() {
        super();
    }

    public Employee(String name, String sn, String mail) {
        super();
        this.name = name;
        this.sn = sn;
        this.mail = mail;
    }

    @Relationship(type="REPORT_TO", direction=Relationship.OUTGOING)
    private Employee manager;

    @Relationship(type="REPORT_TO", direction=Relationship.INCOMING)
    private Set<Employee> staffs = new HashSet<>();

    ...
}

我使用 REST API 作为我的应用程序的接口。当我尝试使用session.loadAll(Employee.class, 0) 返回所有员工时，似乎一切正常，但不会显示任何经理或员工信息。另一方面，如果我使用session.loadAll(Employee.class, 0)，则会返回许多深度的Employee。

例如，如果员工 A 向员工 B 报告，即。 B 是 A 的经理。深度 0 的结果是：

{ "_embedded" : { "employees" : [ { "name" : "B", "sn" : "10001", "mail" : "B@test.com", "manager" : null, "staffs" : [ ], }, { "name" : "A", "sn" : "10000", "mail" : "A@test.com", "manager" : null, "staffs" : [ ], } ] } ... }

虽然深度 1 的结果是： [{"id":9,"name":"A","sn":"10000","mail":"A@test.com","manager":{"id":8,"name":"B","sn":"10001","mail":"B@test.com","manager":null,"staffs":[{"id":9,"name":"A","sn":"10000","mail":"A@test.com","manager":{"id":8,"name":"B","sn":"10001","mail":"B@test.com","manager":null,"staffs":[{"id":9,"name":"A","sn":"10000","mail":"A@test.com","manager":{"id":8,"name":"B","sn":"10001","mail":"B@test.com","manager":null,"staffs":[{"id":9,"name":"A","sn":"10000","mail":"A@test.com","manager":{"id":8,"name":"B","sn":"10001","mail":"B@test.com","manager":null,"staffs":[{"id":9,"name":"A","sn":"10000","mail":"A@test.com","manager":{"id":8,"name":"B","sn":"10001","mail":"B@test.com","manager":null,"staffs":[{"id":9,"name":"A","sn":"10000","mail":"A@test.com","manager":{"id":8,"name":"B","sn":"10001","mail":"B@test.com","manager":null,"staffs":[{"id":9,"name":"A","sn":"10000","mail":"A@test.com","manager":{"id":8,"name":"B","sn":"10001","mail":"B@test.com","manager":null,"staffs":[{"id":9,"name":"A","sn":"10000","mail":"A@test.com","manager":{"id":8,"name":"B","sn":"10001","mail":"B@test.com","manager":null,"staffs":[{"id":9,"name":"A","sn":"10000","mail":"A@test.com","manager":{"id":8,"name":"B","sn":"10001","mail":"B@test.com","manager":null,"staffs":[{"id":9,"name":"A","sn":"10000","mail":"A@test.com",...

我该如何处理这个案子？谁能给我一些建议，拜托。

【问题讨论】：

这是 OGM loadAll 查询的结果还是通过您的 rest api 序列化的结果 Employee？

标签： rest neo4j spring-data-neo4j neo4j-ogm

【解决方案1】：

这是一个 JSON 序列化问题。实体包含循环引用，序列化程序无法检测到它们，因此它进入构造 JSON 对象的无限循环。你可以试试JSOG Jackson 插件，它能够检测并自动处理此类问题。有关如何在 Spring 项目中使用它的示例，请查看 SDN University。

【讨论】：