Spring Boot在json響應中包含OneToMany關聯

Question

我有一個實體

@Entity
public class Post {
    @Id
    private Long id;

    @NotNull
    private Date createdAt;

    @NotNull
    private String text;

    @NotNull
    private Date updatedAt;

    @OneToMany
    private List<Comment> comments;
}

和另一個實體

@Entity
public class Comment {
    @Id
    private Long id;

    @NotNull
    private Date createdAt;

    @NotNull
    private String text;

    @NotNull
    private Date updatedAt;
}

我有一個簡單的控制器，返回給定id的post json

    @RestController
    @RequestMapping("/posts")
    public class ProductDimensionsController {

    @RequestMapping(method = RequestMethod.GET)
    public Post getPost(@RequestParam(value = "id") String id) throws ApiException {
        ...
        ...
        ...
    }
}

我得到回應：

{
"id": 401,
"createdAt": 1482364510614,
"updatedAt": 1482364510614,
"text": "abc",
}

我要關注：

{
"id": 401,
"createdAt": 1482364510614,
"updatedAt": 1482364510614,
"text": "abc",
"comments": [{
    "id": 101,
    "createdAt": 1482364510614,
    "updatedAt": 1482364510614,
    "text": "xyz",
    }]
}

如何在json響應中包含關聯的OneToMany實體？

Answer 1

為了獲得所需的結果，您必須在Comment實體上標記@ManyToOne(fetch = FetchType.LAZY) 。 這將導致以FetchType.LAZY模式獲取結果。

另一種方法可能是：

@Entity
public class Post {
    @Id
    private Long id;

    @NotNull
    private Date createdAt;

    @NotNull
    private String text;

    @NotNull
    private Date updatedAt;

    @OneToMany
    @JsonIgnore
    private List<Comment> comments;

    @JsonIgnore
    public List<Comment> getComments() {
        return comments;
    }

    @JsonProperty
    public void setComments(List<Comment> comments) {
        this.comments = comments;
    }
}