ManyToOne - Foreign Key is not being set when saving

Question

I am using Hibernate and Spring MVC. I have the following form

When I submit the form I want my database tables to fill up like following:

Table Name : student

student_id     studentName
 1.            Jason Stathum

Table Name : studentdetails

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

But when I actually run my application and insert the form data, everything works perfectly except the column city_id do not get filled up. The table looks like following:

Table Name : studentdetails

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

FYI, I have also a table named city which looks like following

Table Name : studentdetails

city_ID  city_name
   1      NewYork

I have included my codes below, Could you please tell me how to fix this problem?

Thank you very much

Entity: Student

@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

Entity : StudentDetails

@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

Entity: City

@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

Controller

@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";   

}

StudentDaoImpl

Session session = getSessionFactory().openSession();
Transaction tx;
tx = session.beginTransaction();
session.save(student);  
tx.commit();

My Form : 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>

Answer 1

I'm speculating here, but could it be that you didn't actually select a city when entering a record, but instead just entered a student name, a father name and a mother name, and left the city displayed at the first city in your list, which happened to be "New York". Perhaps you could add an extra "please choose" option, with a validator that forces you to choose a city.

Also, I notice that you use city_id in some places and city_ID in others. Is your database case-insensitive for column names?

Answer 2

I have manged to solve the problem :) I made some changes in my HTML form and now its working.

<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>