Spring and Hibernate: form of an object containing objects

Question

There is an object called "Man" and an object called "Course" with the attitude of many to many. The union object is called "PersonCourse".

@Entity @Table(name="person_course") public class PersonCourse implements Serializable { @Id @ManyToOne @JoinColumn(name="course_ID") private Course course; @Id @ManyToOne @JoinColumn(name="person_ID") private Person person; // Getter and setters here } 

I have the following form with which I must save information in "PersonCourse":

 <form:form method="post" action="addpersoncourse.html" commandName="personcourse"> <form:label path="person"><spring:message code="label.person"/></form:label> <form:select path="person"> <c:forEach items="${personList}" var="person"> <form:option value="${person.id}">${person.firstName} ${person.lastName}</form:option> </c:forEach> </form:select> <form:label path="course"><spring:message code="label.course"/></form:label> <form:select path="course"> <c:forEach items="${courseList}" var="course"> <form:option value="${course.id}">${course.course}</form:option> </c:forEach> </form:select> <input type="submit" value="<spring:message code="label.addpersoncourse"/>"/> </form:form> 

In the controller, I try to read the information in the following way:

 @RequestMapping(value = "/addpersoncourse", method = RequestMethod.POST) public String addpersoncourse(@ModelAttribute("personcourse") PersonCourse personCourse, BindingResult result) { // HERE personcourse.person and personcourse.course ARE NULL // Other operation I'm supposed to do } 

But for some reason personcourse.person and personcourse.course are null. What could be wrong?

Answer 1

Try changing to:

 <form:select path="person.id"> <form:select path="course.id"> 

or try using Formatters .