为什么我会收到"Request method 'POST' not supported"？我在邮递员上收到错误代码 405

Question

邮差错误

控制器:

@RestController

@RequestMapping("/student_enrollment/class_subject"

公共类ClassController {

private ClassService classService;
public ClassController(ClassService classService) {
super();
this.classService = classService;
}

@PostMapping ()

public ResponseEntity<Classes> saveClass(@RequestBody Classes classes) {
return new ResponseEntity<Classes>(classService.saveClass(classes), 
HttpStatus.CREATED);
}
@GetMapping
public List<Classes> getAllClasses() {
return classService.getAllClasses();
}

模型:

@ data@ entity

@Table(name = "class_subject")

公共类ClassSubject {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int subject_id;
@Column(value = "prerequisite")
private String prerequisite;
@Column(value = "max_capacity")
private int max_capacity;

}

服务impl:

@ service公共类ClassServiceImpl实现ClassService{

@Override

public ClassSubject updateClassSubject(ClassSubject classSubject, int classSubjectId) {

ClassSubject existingClassSubject = classSubjectRepository.findById(classSubjectId).orElseThrow(() -> new ResourceNotFoundException("ClassSubject", "classSubjectId", classSubjectId));

existingClassSubject.setSubject_id(classSubject.getSubject_id());
existingClassSubject.setPrerequisite(classSubject.getPrerequisite());
existingClassSubject.setMax_capacity(classSubject.getMax_capacity());

classSubjectRepository.save(existingClassSubject);

return existingClassSubject;
}

服务:

ClassService公共接口

Classes saveClass(Classes classes);
List<Classes> getAllClasses();
Classes getClassByID(int classId);
Classes updateClass(Classes classes, int classId);
void deleteClass(int classId);

}

SQL查询:

CREATE TABLE ( )

subject_id INT NOT NULL,
prerequisite VARCHAR(30),
max_capacity INT NOT NULL,
PRIMARY KEY (subject_id)

);

Answer 1

因为在Postman中您使用的是PUT方法，而不是POST方法。

Answer 2

让我猜你期望'subject_id'使用数据库序列自动生成。那么你就缺少了两个注释@GeneratedValue和@SequenceGenerator。

因为'subject_id'不是可选字段。这就是为什么你得到错误"字段'subject_id'没有默认值"。

要创建'subject_id'字段和DB序列之间的关系，请使用以下命令:

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@SequenceGenerator(name="seq",sequenceName="sequence_in_db")        
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="seq")   
private int subject_id;

你可以找到更多关于这个主题的细节。注释@Id和@GeneratedValue(strategy = GenerationType.IDENTITY)的用途是什么?为什么生成类型是identity?