HTTP状态500-请求处理失败；嵌套的异常是org。冬眠例外ConstraintViolationException:无法执行语句

Question

我正在尝试添加/更新学生，但在更新学生时，我收到一个错误。但在添加学生时，效果很好。我在更新时遇到此错误：-

HTTP状态500-请求处理失败；嵌套异常是org.springframework.dao.数据完整性违反异常：无法执行语句；SQL[n/a]；约束[null]；嵌套异常是org.hibernate.exception.约束违反异常：无法执行语句

add-students.jsp

<form:form action="addStudent" enctype="multipart/form-data" modelAttribute="addstd" method="POST" >
    <form:hidden path="id" />
     ${message}
    <form:errors path="firstName" cssClass="error" />
    <form:input path="firstName" placeholder="Fistname" />

    <form:errors path="lastName" cssClass="error" />
    <form:input path="lastName" placeholder="Lastname" />

    <form:input path="contact_No" placeholder="Contact Number" />
    <form:input path="address" placeholder="Address" />

    <form:errors path="email" cssClass="error" />
    <form:input path="email" placeholder="Email" />

    <p class="msg">
        Year:
    <form:select path="year">
            <c:forEach var="temp" items="${studentyear}">
            <form:option value="${temp.yearId}">${temp.year}</form:option>
            </c:forEach>
        </form:select> 

      Faculty: 
        <form:select path="faculty">
            <c:forEach var="temp" items="${studentfaculty}">
            <form:option value="${temp.faculty_id}" >${temp.faculty}</form:option>
            </c:forEach>
        </form:select>
      Profile: <input type="file" name="image" accept="image/*" />

    </p>
    <input type="submit" value="Add/Update Record" class="button" />
</form:form>

@控制器类

@RequestMapping(value="/addStudent",method=RequestMethod.POST)
public String saveStudent(@RequestParam("image") MultipartFile file,@RequestParam("id") int theId,@ModelAttribute("addstd") @Valid StudentInfo theStudent,BindingResult result,Model model){
    String fileName=null; 
    if(!file.isEmpty()){

        try {
            String path= session.getServletContext().getRealPath("/resources/images");
            String newName=String.valueOf(new java.util.Date().getTime());
            fileName=file.getOriginalFilename();
            String ext=FilenameUtils.getExtension(fileName);
            if(ext.equalsIgnoreCase("jpg") || ext.equalsIgnoreCase("jpeg") || ext.equalsIgnoreCase("png")){
            File imageFile=new File(path,newName+"."+ext);
            file.transferTo(imageFile);
            theStudent.setImages(newName+"."+ext);

            if(theId!=0){
               StudentInfo std=studentService.getStudent(theId);
               String images= std.getImages();
               File oldImage=new File(path,images);
            Files.delete(oldImage.toPath());
            }
            }
        } catch (Exception e) {

        }
    }
    if(result.hasErrors()){


    List <Year> theYear = studentService.getYear();
    model.addAttribute("studentyear",theYear);

    List<Faculty> theFaculty=studentService.getFaculty();
    model.addAttribute("studentfaculty",theFaculty);
        return "add-students";
    }else{
        studentService.saveStudent(theStudent);
        return "redirect:/login";

        }
}

@RequestMapping("/showFormForUpdate")
public String showUpdateStudent(@RequestParam("studentId") int theId, Model model){

     StudentInfo theStudent=studentService.getStudent(theId);
     model.addAttribute("addstd",theStudent);

    List <Year> theYear = studentService.getYear();
    model.addAttribute("studentyear",theYear);

    List<Faculty> theFaculty=studentService.getFaculty();
    model.addAttribute("studentfaculty",theFaculty);
     return "add-students";
}

学生道。班

 public void saveStudent(StudentInfo theStudent) {
    Session currentSession=sessionFactory.getCurrentSession();       
    currentSession.saveOrUpdate(theStudent);

}

学生信息。班

@Entity
@Table (name="studentinfo")
public class StudentInfo implements Serializable {

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


@Column(name="year_id")
private int year;


@Column(name="faculty_id")
private int faculty;

@NotEmpty(message="First Name cannot be empty")
@Column(name="firstname")
private String firstName;

@NotEmpty(message="Last Name cannot be empty")
@Column(name="lastname")
private String lastName;

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

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


@Email(message="Enter a valid email address")
@Column(name="email")
private String email;


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

@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name="ID")
private User user;

 //getter and setter here

使用者班

@Entity
@Table(name="user")
public class User {

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

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

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

@OneToOne(mappedBy = "user",fetch = FetchType.LAZY)
private StudentInfo info;

//getter and setter here

Answer 1

在StudentInfo类中，有一个字段：

private User user;

您尚未将用户映射到表单控制器中的任何字段。

您可以这样映射您的用户：

<form:hidden path="user.user_id"/>

如果你想让这个值为null然后提供

nullable = true

在一对一的注释中，也允许在db中为null。

如果你正在做添加学生，并且你没有用户为空，那么你将不得不以某种方式将用户注入你的控制器。

例如，在您的控制器方法中，当添加新的学生信息时，从数据库获取用户信息，然后注入学生信息。我写的sudo代码如下：

// User user = session.get(User.class, 1);
// studentInfo.setUser(user);
// saveorUpdate studentInfo