Java ManyToOne-保存时未设置外键

我正在使用Hibernate和SpringMVC。我有以下表格

当我提交表单时，我希望我的数据库表填写如下：

表名：学生

student_id     studentName
 1.            Jason Stathum

@Entity
@Table(name = "student")
public class Student {

@Id 
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name="student_id", nullable= false)
private Integer studentId;
private String studentName;

@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name="student_id", referencedColumnName="student_id")
private List<StudentDetails> studentDetails = new ArrayList<StudentDetails>();

// Getters and Setters

表名：studentdetails

studentDetailsid   FatherName   MotherName    city_id    student_id
   1                 Mr.X          Mrs. Y        1          1

studentDetailsid   FatherName   MotherName    city_id    student_id
   1                 Mr.X          Mrs. Y       NULL          1

city_ID  city_name
   1      NewYork

@Entity
@Table(name = "studentDetails")
public class StudentDetails {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer studentDetailsId;
private String FatherName;
private String MotherName;

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name="city_id")
private City city;

// Getters and Setters

但是当我实际运行我的应用程序并插入表单数据时，除了列

city\u id

没有被填满之外，其他一切都正常工作。该表如下所示：

表名：studentdetails

studentDetailsid   FatherName   MotherName    city_id    student_id
   1                 Mr.X          Mrs. Y        1          1

studentDetailsid   FatherName   MotherName    city_id    student_id
   1                 Mr.X          Mrs. Y       NULL          1

city_ID  city_name
   1      NewYork

@Entity
@Table(name = "studentDetails")
public class StudentDetails {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer studentDetailsId;
private String FatherName;
private String MotherName;

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name="city_id")
private City city;

// Getters and Setters

仅供参考，我还有一个名为city的表，如下所示

表名：studentdetails

studentDetailsid   FatherName   MotherName    city_id    student_id
   1                 Mr.X          Mrs. Y        1          1

studentDetailsid   FatherName   MotherName    city_id    student_id
   1                 Mr.X          Mrs. Y       NULL          1

city_ID  city_name
   1      NewYork

@Entity
@Table(name = "studentDetails")
public class StudentDetails {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer studentDetailsId;
private String FatherName;
private String MotherName;

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name="city_id")
private City city;

// Getters and Setters

我已经在下面列出了我的代码，你能告诉我如何解决这个问题吗

多谢各位

实体：学生

student_id     studentName
 1.            Jason Stathum

@Entity
@Table(name = "student")
public class Student {

@Id 
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name="student_id", nullable= false)
private Integer studentId;
private String studentName;

@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name="student_id", referencedColumnName="student_id")
private List<StudentDetails> studentDetails = new ArrayList<StudentDetails>();

// Getters and Setters

实体：城市

@Entity
@Table(name = "CITY")
public class City {

  @Id
  @Column(name="city_ID")
  @GeneratedValue
  private int cityId;

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

  // Getters and Setters

控制器

@RequestMapping(value="addstudent", method = RequestMethod.GET)
public String addStudent(@ModelAttribute("secret") Student student, BindingResult result, Model map)
{
    map.addAttribute("student", new Student());     
    List<City> myCities = subService.getCity();     
    map.addAttribute("city", myCities);     
    return "addStudent";
}

@RequestMapping(value="addstudent", method = RequestMethod.POST)
public String saveStudent(@ModelAttribute("secret") Student student, BindingResult result, Model map)
{
    studentService.addStudent(student);
    map.addAttribute("success", "Submitted");
    return "msg";   

}

我的表单：addStudent.jsp

<c:url var="saveUrl" value="/addstudent" />
<form:form modelAttribute="secret" method="POST" action="${saveUrl}">
   <table>
     <tr>
        <td><form:label path="studentName">Student Name:</form:label></td>
        <td><form:input path="studentName"/></td>
    </tr> 

    <tr>
       <td><form:label path="studentDetails[0].fatherName">Father Name:</form:label></td>
       <td><form:input path="studentDetails[0].fatherName"/></td>
   </tr>

    <tr>
       <td><form:label path="studentDetails[0].motherName">Mother Name:</form:label></td>
       <td><form:input path="studentDetails[0].motherName"/></td>
   </tr>

    <tr>
       <td><label>City</label></td>
       <td><form:select path="studentDetails[0].city">
        <c:forEach var="row" items="${city}">
            <option value="${row.cityId}">${row.city}</option>          
        </c:forEach>
       </form:select> 
      </td>
   </tr>
</table>

<input type="submit" value="Save" />
</form:form>

学生姓名：
父亲姓名：
母亲姓名：
城市
${row.city}

我在这里猜测，是不是在输入记录时，您实际上没有选择一个城市，而是输入了一个学生姓名、父亲姓名和母亲姓名，并将该城市显示在列表中的第一个城市，碰巧是“纽约”。也许您可以添加一个额外的“请选择”选项，使用验证器强制您选择一个城市

---

另外，我注意到您在某些地方使用city\u id，而在其他地方使用city\u id。您的数据库对列名不区分大小写吗？

我已经设法解决了这个问题：）我在HTML表单中做了一些更改，现在可以使用了

<tr>
  <td><label>City</label></td>
   <td><form:select path="studentDetails[0].city.cityId">
        <c:forEach var="row" items="${city}">
            <option value="${row.cityId}">${row.cityName}</option>          
        </c:forEach>
       </form:select> 
    </td>
</tr>

城市
${row.cityName}

您正在设置

城市名称

而不是

学生

中

城市

的

id

，谢谢您的回复。我尝试了额外的“请选择”选项，但它不起作用。我使用

city\u ID

来引用我的

city

表，我使用

city\u ID

来引用

studentDetails

表中的外键列。我认为我的数据库对列名不区分大小写。谢谢