在 Spring Rest Controller 中出现 JSON 解析错误 (MismatchedInputException)

Question

我对 Spring 很陌生。当我在 Postman 中尝试 POST 方法时出现 JSON 解析错误。基本上，我有一个 class 我想以列表的形式调用另一个。

我有一个用于 classes 的抽象实体，然后我有一个标签 class;

@Entity
@Data
@EqualsAndHashCode(callSuper = true)
public class Tag extends AbstractEntity {

    @Column (nullable = false)
    private String tag;

我有一个问题class:

@Entity
@Data
@EqualsAndHashCode(callSuper = true)
public class Question extends AbstractEntity {

    @Column (nullable = false)
    private String title;
    @Column (nullable = false)
    private String content;
    @OneToMany
    @Column (nullable = false)
    private List<Tag> tag;

这是我的控制器：

@RestController
@RequestMapping("v1/enquiry")
public class EnquiryController {

    @Autowired
    private QuestionRepository questionRepository;

    @PostMapping
    public ResponseEntity<Question> createEnquiry(@RequestBody Question question) {
        if (question.getTitle() == null | question.getContent() == null) {
            throw new BadRequest("Please fill in the required fields!");
        }

        Question enq = questionRepository.save(question);
        return ResponseEntity.ok().body(enq);
    }

当我使用 POST 方法时：

{ 
   "title": "question",
   "content": "cogito",
   "tag": ["java", "rest"]
}

我收到以下错误。我已经尝试了所有针对类似条件的建议。 None 他们成功了。我做错了什么？

"message": "JSON parse error: Cannot construct instance of com.mockup.mockupapi.model.Tag (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('java'); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of com.mockup.mockupapi.model.Tag (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('java')\n at [Source: (PushbackInputStream); line: 4, column: 10] (through reference chain: com.mockup.mockupapi.model.Question[\"tag\"]->java.util.ArrayList[0])",

SOLVED

感谢评论中的线索，我更改了 JSON 中的数组格式，并将 CascadeType 添加到 OneToMany 调用中。我使用 .PERSIST，但是，.ALL 也可以。

JSON格式：

{ 
   "title": "question",
   "content": "cogito",
   "tag": [{"tag":"java"},{"tag": "rest"}]
}

问题class：

@Entity
@Data
@EqualsAndHashCode(callSuper = true)
public class Question extends AbstractEntity {

    @Column (nullable = false)
    private String title;
    @Column (nullable = false)
    private String content;
    @OneToMany(cascade = CascadeType.PERSIST)
    @Column (nullable = false)
    private List<Tag> tag;

Answer 1

请更改您的 JSON 结构。

{ "title": "question", "content": "cogito", "tag": [{"tag":"java"},{"tag": "rest"}] }

同时在您的映射中添加级联。

@OneToMany (cascade = CascadeType.ALL)
 @Column (nullable = false) 
 private List<Tag> tag;

在 Spring Rest Controller 中出现 JSON 解析错误 (MismatchedInputException)

Getting JSON parsing error (MismatchedInputException) in Spring Rest Controller

java

rest

spring

jackson

spring-restcontroller