When an entity is converted to JSON, the field with null value is lost

Entity transfer JSON when , The value is null Missing fields for

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1. There is an entity class , The code is as follows ：

@Data
public class StudentEntity implements Serializable {
    

    private static final long serialVersionUID = 2127997065197153097L;
    
    private String name;
    private String sex;
    private Integer age;
    private String phone;
}

2. There is a Get Interface , The code is as follows ：

@RequestMapping("student/")
@RestController
public class StudentController {
    

    @GetMapping("get_student")
    public StudentEntity getStudent() {
    
        StudentEntity student = new StudentEntity();
        student.setName(" Zhang San ");
        student.setAge(23);
        student.setSex(" male ");
        //  take ‘ Phone number ’ The assignment is null
        student.setPhone(null);
        return student;
    }
}

3. Call the interface , The data received are as follows ：

{
    
  "name": " Zhang San ",
  "sex": " male ",
  "age": 23,
  "phone":null
}

4. Add the following configuration to the configuration file :

spring.jackson.default-property-inclusion=non_null

5. Restart project , Call the interface again , The data received are as follows :

{
    
  "name": " Zhang San ",
  "sex": " male ",
  "age": 23
}

You can find , The value is null Of ’phone’ Not sent to front end .

6. Remove section 4 Step to add the configuration , Yes StudentEntity Modify the entity class as follows :

@Data
public class StudentEntity implements Serializable {
    

    private static final long serialVersionUID = 2127997065197153097L;
    
    private String name;
    private String sex;
    private Integer age;
    
    @JsonInclude(JsonInclude.Include.NON_NULL)
    private String phone;
}

7. Restart project , Call the interface again , The data received are as follows :

{
    
  "name": " Zhang San ",
  "sex": " male ",
  "age": 23
}

summary

stay Spring In the project , When the back end sends entity data to the front end , The rejection value is null There are two ways to use the fields of :

1. Modify the configuration file , Add the following configuration :

spring.jackson.default-property-inclusion=non_null

2. Modify entity class , Add the following comments to the required fields :

@JsonInclude(JsonInclude.Include.NON_NULL)

Empathy , Some key value pairs in the data received by the front end from the back end " take wings to itself ", The back end can check whether the system has added the above configuration or annotation .