Question

您好我正在关注CRUD tuts，我正在尝试在表中编写类。但是我被卡住了......

Classes.java

@Entity
@Table(name = "Classes")
public class Classes {

    @Id 
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "class_id", unique = true, nullable = false)
    private String classId;

    @Column(name = "name")
    private String name;

    @Column(name = "description")
    private String description;

    @Column(name = "max_numb_students")
    private int max_numb_students;

    @Column(name = "min_numb_students")
    private int min_numb_students;

    public String getClassId() {
        return classId;
    }
    public void setClassId(String classId) {
        this.classId = classId;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
    public int getMax_numb_students() {
        return max_numb_students;
    }
    public void setMax_numb_students(int max_numb_students) {
        this.max_numb_students = max_numb_students;
    }
    public int getMin_numb_students() {
        return min_numb_students;
    }
    public void setMin_numb_students(int min_numb_students) {
        this.min_numb_students = min_numb_students;
    }

    public Classes() {

    }

    public Classes(String classId, String name, String description, int max_numb_students, int min_numb_students) {
        super();
        this.classId = classId;
        this.name = name;
        this.description = description;
        this.max_numb_students = max_numb_students;
        this.min_numb_students = min_numb_students;
    }

}

Controller.java

@Controller
@RequestMapping("/classesTable")
public class ClassesController {
    @Autowired 
    private ClassesRepository classesRepository;

    @RequestMapping(value="", method=RequestMethod.GET)
    public String listClasses(Model model){
        model.addAttribute("classes", classesRepository.findAll());
        return "classesTable";
    }

      @RequestMapping(value = "/{classId}/delete", method = RequestMethod.GET)
        public ModelAndView delete(@PathVariable String classId) {
          System.out.println(classId);
          classesRepository.delete(classId);
            return new ModelAndView("redirect:/classesTable");
        }
}

ClassesRepository.java

public interface ClassesRepository extends CrudRepository<Classes,String>{

}

我收到此错误

出现意外错误（type = Internal Server Error，status = 500）。没有类id为{classId}的com.oggi.model.Classes实体！

Answer 1

我创建了一个这样的项目并使用String id工作正常，唯一的区别是我使用JpaRepository而不是CrudRepo。使用long id是一个更好的解决方案，但是如果你需要String id，它也可以工作。

domain：DataCenters.java

a.click()

回购：DataCentersRepository

@Entity
public class DataCenters {


    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private String id;

    private String name;

    private String location;

    public DataCenters() {
    }

    public DataCenters(String name, String location) {
        this.name = name;
        this.location = location;
    }


    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getLocation() {
        return location;
    }

    public void setLocation(String location) {
        this.location = location;
    }

    @Override
    public String toString() {
        return "DataCenters{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", location='" + location + '\'' +
                '}';
    }

}

controller：DataCentersController

public interface DataCentersRepository extends JpaRepository<DataCenters,String> {
}

启动应用程序：MyJpademoApplication

@Controller
@RequestMapping("/datacenters")
public class DataCentersController {

    private final DataCentersRepository dataCentersRepository;

    @Autowired
    public DataCentersController(DataCentersRepository dataCentersRepository){
        this.dataCentersRepository=dataCentersRepository;
    }

    @RequestMapping(value="", method=RequestMethod.GET)
    public String listClasses(Model model){
        model.addAttribute("datacenters", dataCentersRepository.findAll());
        return "datacenters";
    }

    @RequestMapping(value = "/{id}/delete", method = RequestMethod.GET)
    public ModelAndView delete(@PathVariable String id) {
        System.out.println(id);
        dataCentersRepository.delete(id);
        return new ModelAndView("redirect:/datacenters");
    }


}

application.properties

@SpringBootApplication
public class MyjpademoApplication {

    private static final Logger logger = LoggerFactory.getLogger(MyjpademoApplication.class);

    public static void main(String[] args) {
        SpringApplication.run(MyjpademoApplication.class, args);
    }

    @Bean
    public CommandLineRunner runner(ServerRepository serverRepository, DataCentersRepository dataCentersRepository){
        return (args) -> {

            logger.info("Creating Data Centers...");
            dataCentersRepository.save(new DataCenters("StarFox","nowhere"));
            dataCentersRepository.save(new DataCenters("Axelay","nowhere"));
            dataCentersRepository.save(new DataCenters("NinjaGaiden","nowhere"));
            dataCentersRepository.findAll().stream().forEach(System.out::println);

        };}}

的pom.xml

spring.h2.console.enabled=true
spring.h2.console.path=/h2-console
spring.datasource.url:jdbc:h2:mem:~/test

Crud app - Spring boot

1 个答案: