Spring - Fehler beim Konvertieren des Eigenschaftswerts vom Typ java.lang.String in den erforderlichen Typ

Question

Ich mache ein Projekt der Housing Association im Frühjahr.

Wenn ich versuche, ein Objekt zu meiner Liste der Wohnungen hinzufügen Ich erhalte einen Fehler, der irgendwie auf der Seite geschrieben: https://s28.postimg.org/vrhy6mbd9/blad.jpg

Apartments haben Beziehung Viele zu einem Gebäude.

Apartment Controller:

package pl.dmcs.spoldzielnia.controllers; 

import java.util.Map; 

import javax.servlet.http.HttpServletRequest; 

import org.springframework.beans.factory.annotation.Autowired; 
import org.springframework.stereotype.Controller; 
import org.springframework.validation.BindingResult; 
import org.springframework.web.bind.ServletRequestUtils; 
import org.springframework.web.bind.annotation.ModelAttribute; 
import org.springframework.web.bind.annotation.PathVariable; 
import org.springframework.web.bind.annotation.RequestMapping; 
import org.springframework.web.bind.annotation.RequestMethod; 
import org.springframework.web.bind.annotation.SessionAttributes; 
import org.springframework.web.servlet.ModelAndView; 

import pl.dmcs.spoldzielnia.domain.Apartment; 
import pl.dmcs.spoldzielnia.service.ApartmentService; 
import pl.dmcs.spoldzielnia.service.BuildingService; 




@Controller 
@SessionAttributes 
public class ApartmentController { 

    @Autowired 
    ApartmentService apartmentService; 



    @Autowired 
    BuildingService buildingService; 



    @RequestMapping("admin/apartment") 
    public String listApartment(Map<String, Object> map, HttpServletRequest request) { 

     int apartmentId = ServletRequestUtils.getIntParameter(request, "apartmentId" , -1); 

     if (apartmentId > 0) 
     { 
      Apartment apartment = apartmentService.getApartment(apartmentId); 

      apartment.setBuilding(buildingService.getBuilding(apartmentService.getApartment(apartmentId).getBuilding().getId())); 


      map.put("selectedBuilding", apartmentService.getApartment(apartmentId).getBuilding().getId()); 
      map.put("apartment", apartment); 
     } 
     else 
      map.put("apartment", new Apartment()); 


     map.put("buildingList", buildingService.listBuilding()); 
     map.put("apartmentList", apartmentService.listApartment()); 

     return "apartment"; 
    } 

    @RequestMapping(value = "admin/addApartment", method = RequestMethod.POST) 
    public String addContact(@ModelAttribute("apartment") Apartment apartment, BindingResult result, 
      HttpServletRequest request, Map<String, Object> map) { 



     if (result.getErrorCount()==0) 
     { 
      if (apartment.getId()==0) 
      { 

       if (apartment.getBuilding().getId() > 0) 
        apartment.setBuilding(buildingService.getBuilding(apartment.getBuilding().getId())); 
       apartmentService.addApartment(apartment); 
      } 
      else 
      { 

       apartmentService.editApartment(apartment); 
      } 


      return "redirect:/admin/apartment.html"; 
     } 


     map.put("buildingList", buildingService.listBuilding()); 
     map.put("apartmentList", apartmentService.listApartment()); 
     return "apartment"; 
    } 

    @RequestMapping("admin/delete/apartment/{apartmentId}") 
    public String deleteApartment(@PathVariable("apartmentId") Integer apartmentId) { 
     apartmentService.removeApartment(apartmentId); 

     return "redirect:/admin/apartment.html"; 
    } 
// @RequestMapping("/apartment") 
// public ModelAndView showContacts() { 
//   
//  return new ModelAndView("apartment", "command", new Apartment()); 
// } 

Domain:

package pl.dmcs.spoldzielnia.domain; 

import javax.persistence.Column; 
import javax.persistence.Entity; 
import javax.persistence.GeneratedValue; 
import javax.persistence.GenerationType; 
import javax.persistence.Id; 
import javax.persistence.ManyToOne; 
import javax.persistence.Table; 


@Entity 
@Table(name="apartment") 
public class Apartment { 

    @Id 
    @GeneratedValue(strategy = GenerationType.AUTO) 
    int id; 
    @Column(name="apartmentNumber", nullable=false) 
    private String number; 

    public String getNumber() { 
     return number; 
    } 
    public void setNumber(String number) { 
     this.number = number; 
    } 
    public int getId() { 
     return id; 
    } 
    public void setId(int id) { 
     this.id = id; 
    } 




    @ManyToOne 
    private Building building; 

    public Building getBuilding() { 
     return building; 
    } 
    public void setBuilding(Building building) { 
     this.building = building; 
    } 
} 


} 

Building Service Implementation:

package pl.dmcs.spoldzielnia.service; 

import java.util.List; 

import org.springframework.beans.factory.annotation.Autowired; 
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder; 
import org.springframework.stereotype.Service; 
import org.springframework.transaction.annotation.Transactional; 

import pl.dmcs.spoldzielnia.dao.BuildingDAO; 
import pl.dmcs.spoldzielnia.domain.Building; 
import pl.dmcs.spoldzielnia.domain.Building; 

@Service 
@Transactional 
public class BuildingServiceImpl implements BuildingService{ 

    @Autowired 
    BuildingDAO buildingDAO; 

    @Transactional 
    public void addBuilding(Building building) { 


     buildingDAO.addBuilding(building); 
    } 

    @Transactional 
    public List<Building> listBuilding() { 

     return buildingDAO.listBuilding(); 
    } 

    @Transactional 
    public Building getBuilding(int id) { 
     return buildingDAO.getBuilding(id); 
    } 

    @Transactional 
    public void removeBuilding(int id) { 
     buildingDAO.removeBuilding(id); 
    } 

    @Transactional 
    public void editBuilding(Building building) { 

     buildingDAO.editBuilding(building); 
    } 
} 

Können Sie mir helfen, mein Problem zu lösen?

Answer 1

Das Problem ist, dass Sie davon ausgehen, dass Spring MVC in der Lage sein wird, Ihr Apartment-Objekt aus den übergebenen Daten zu füllen. Aus dem Formular sieht es so aus, als wäre die Gebäudenummer 12, was wahrscheinlich ein eindeutiger Bezeichner für das Gebäude in der Datenbank ist, aber wie wird Spring MVC wissen, wie man in die Datenbank geht, das richtige Gebäudeobjekt abruft und es in den Apartment Objekt?

Denken Sie daran, dass Objekte, die über SpringMVC-Parameter zugeordnet werden, normale Java-POJOs und keine Hibernate-angehängten Entitäten sind. Wenn also das Mapping stattfindet, versucht SpringMVC, "12" in das Gebäudeattribut vom Typ Building in Ihr POJO zu setzen (was den Fehler erklärt, den Sie bekommen).

Sie haben zwei Möglichkeiten: Zuerst Sie einen benutzerdefinierten Formatierer registrieren kann, dass die gebenen ID verwenden wird ein Gebäude aus der Datenbank abgerufen werden:

import org.springframework.core.convert.converter.Converter; 

public class BuildingIdToBuildingConverter implements Converter<String, Building> { 

    private BuildingService buildingService; 

    public BuildingIdToBuildingConverter(BuildingService buildingService) { 
     this.buildingService = buildingService; 
    } 

    @Override 
    public Building convert (String id) { 
      return buildingService.getBuilding(id); 
    } 
} 

und registrieren Sie es:

public class AppConfig extends WebMvcConfigurerAdapter { 

    ... 

    @Bean 
    public BuildingService buildingService(){ 
     return new BuildingService(); 
    } 

    @Override 
    public void addFormatters (FormatterRegistry registry) { 
     registry.addConverter(new BuildingIdToBuildingConverter(buildingService())); 
    } 
} 

Zweitens, führen Sie dies manuell aus, indem Sie die Gebäude-ID in einem separaten Parameter senden:

@RequestMapping(value = "admin/addApartment", method = RequestMethod.POST) 
    public String addContact(@ModelAttribute("apartment") Apartment apartment, @RequestParam("buildingId") String buildingId, BindingResult result, HttpServletRequest request, Map<String, Object> map) { 
     if (result.getErrorCount()==0){ 
      if (apartment.getId()==0){ 
       apartment.setBuilding(buildingService.getBuilding(buildingId)); 
       apartmentService.addApartment(apartment); 
      } 
     } 
     else{ 
      apartmentService.editApartment(apartment); 
     } 

     return "redirect:/admin/apartment.html"; 
    } 

    map.put("buildingList", buildingService.listBuilding()); 
    map.put("apartmentList", apartmentService.listApartment()); 
    return "apartment"; 
} 

Und ändern Sie Ihren HTML-Code entsprechend, um den buildingId-Wert zu senden.