列表<object> null 在 Spring 启动 Z594C103F2C6E04C3D8AB059F031E0C1 中反序列化 json 时<div id="text_translate"><p>我在 Spring 引导应用程序中遇到了 controller 问题。 当我在 controller（URI/调用）上进行调用时，object 列表始终是 null。</p><pre> { "code": "TEST", "name": "TEST NAME", "groupe": "A1", "list": [ {"type":"web", "link":"https://google.com/"}, {"type":"web", "link":"https://google2.com/"} ] }</pre><pre class="lang-java prettyprint-override"> @PostMapping(value="/call") public ResponseEntity&lt;Void&gt; ajouterEnvironnement(@RequestBody First first) { first.getCode() // value: "TEST" first.getList() // value: null }</pre><pre class="lang-java prettyprint-override"> public class First { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private int id; private String code; private String name; private String groupe; @OneToMany(mappedBy = "first", cascade = CascadeType.ALL, fetch = FetchType.EAGER) private List&lt;Second&gt; list; }</pre><pre class="lang-java prettyprint-override"> public class Second { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private int id; private String type; private String link; @ManyToOne(fetch = FetchType.EAGER) @JoinColumn(name = "first_id", nullable = false) private First first; }</pre></div></object>

Question

我在 Spring 引导应用程序中遇到了 controller 问题。 当我在 controller（URI/调用）上进行调用时，object 列表始终是 null。

{
    "code": "TEST",
    "name": "TEST NAME",
    "groupe": "A1",
    "list": [
        {"type":"web", "link":"https://google.com/"},
        {"type":"web", "link":"https://google2.com/"}
    ]
}

@PostMapping(value="/call")
    public ResponseEntity<Void> ajouterEnvironnement(@RequestBody First first) {
        first.getCode() // value : "TEST"
        first.getList() // value : null
}

public class First {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String code;
    private String name;
    private String groupe;
    @OneToMany(mappedBy = "first", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private List<Second> list;
}

public class Second {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String type;
    private String link;
    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "first_id", nullable = false)
    private First first;
}

Answer 1

通过写这个问题，我能够找到一个解决方案，所以我分享它：

使用@JsonManagedReference和@JsonBackReference注释。

更多信息在这里。

public class First {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String code;
    private String name;
    private String groupe;
    @OneToMany(mappedBy = "first", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    @JsonManagedReference
    private List<Second> listLiens;
}

public class Second {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String type;
    private String link;
    @ManyToOne(fetch = FetchType.EAGER)
    @JsonBackReference
    @JoinColumn(name = "first_id", nullable = false)
    private First first;
}