使用胸腺和春季靴子填充列表的下拉菜单

Question

我正在尝试使用Spring Boot和Thymeleaf添加来自数据库中数据的HTML选择。我无法理解我做错了什么。 这是连接到此问题的代码：

我的模型：

@Entity // This tells Hibernate to make a table out of this class
@Table(name = "Skill")
public class Skill {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="skillID")
    private int skillID;
    
    @Column(name="skillname")
    private String skillname;

    @OneToMany(mappedBy = "skill")
    private Collection<UserSkill> UserSkills = new ArrayList<>();

    public Skill() {
    }
    
      // constructors

    public Skill(int skillID, String skillname, Collection<UserSkill> userSkills) {
        this.skillID = skillID;
        this.skillname = skillname;
        this.UserSkills = userSkills;
    }
    
    // getter and setter

    public int getSkillID() {
        return skillID;
    }


    public void setSkillID(int skillID) {
        this.skillID = skillID;
    }

    public String getSkillname() {
        return skillname;
    }

    public void setSkillname(String skillname) {
        this.skillname = skillname;
    }

    public Collection<UserSkill> getUserSkills() {
        return UserSkills;
    }

    public void setUserSkills(Collection<UserSkill> userSkills) {
        UserSkills = userSkills;
    }
    
      @Override
      public String toString() {
          return "Skill [skillID=" + skillID + ", skillname=" + skillname + ", UserSkills=" + UserSkills + "]"; }
     
}

我的控制器：

@Controller
public class SkillController {

    @Autowired
    private SkillService skillService;

    public SkillController(SkillService skillService) {
        this.skillService = skillService;
    }

      @GetMapping("/skill")
      public String skill(Model theModel) {
          Skill theSkill = new Skill();
         // add existing users to the spring model
        theModel.addAttribute("skills", skillService.getSkills());
        return "skill";
        }

我的html thymeleaf（view）：

<div class="form-group col-md-8">
<label  class="col-form-label">Category </label>
<select  id="category" name="category" th:field="*{skill.skillID}" >
<option th:each="skill : ${skills}" th:value="${skill.skillID}" th:utext="${skill.skillname}"/>
</select>
</div>

我的仓库：

@Repository
public interface SkillRepository extends JpaRepository<Skill, Integer> {
    Skill findSkillBySkillname(String skillname);
}

我的服务（接口）：

@Service
public interface SkillService {

    Skill getSkill(String skillname);
    Iterable<Skill>getSkills();
    Skill findBySkillId(int theSkillID);
}

我的serviceimpl（interface）：

@Service
public class SkillServiceImpl implements SkillService {

    private final SkillRepository skillRepository;
    
    /*
     * @Autowired SkillRepository skillRepository;
     */

    @Autowired
    public SkillServiceImpl(SkillRepository theSkillRepository) {
        skillRepository = theSkillRepository;

    }

    @Override
    public Iterable<Skill> getSkills() {
        System.out.println("Abrufen aller Skills.");
        return skillRepository.findAll();
    }

    @Override
    public Skill getSkill(String skillname) {
        System.out.println("Abrufen des Skills "+ skillname);
        return skillRepository.findSkillBySkillname(skillname);
    }


    @Override
    public Skill findBySkillId(int theSkillID) {
        Optional<Skill> result = skillRepository.findById(theSkillID);
        Skill theSkill = null;
        if (result.isPresent()) {
            theSkill = result.get();
        }
        else {
            // we didn't find the vaccination state
            throw new RuntimeException("Did not find user id - " + theSkillID);
        }
        return theSkill;
    }

我得到此错误：

ERROR 94396 --- [nio-8080-exec-4] o.a.c.c.C.[.[.[.[dispatcherServlet]      : Servlet.service() for servlet [dispatcherServlet] in context with path [/webapp] threw exception [Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates/skill.html]")] with root cause

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'skill' available as request attribute

Answer 1

在您的控制器中，将 theskill 添加到模型中。您创建了它，但没有将其添加到模型中。错误表明您正在引用表格备份对象，但模型中不存在。