Question

Could someone please help me find out why my attempt to bind Collection to the form in Spring MVC is not working?

Here is how my object looks like –

public class TestObj {
   private Integer testNumber;
   private String home;
   private String destination;
}

Here is my form object that contains list of above object –

public class TestForm {
   private List<TestObj> testList;
   //contains getter and setter for testList
}

In my controller, I have implemented formBackingObject method –

public class MyController extends SimpleFormController {

    public MyController() {
        setCommandClass(TestForm.class);
        setCommandName("testForm");
    }

        protected Object formBackingObject(HttpServletRequest request) throws Exception {
           if (isFormSubmission(request)) {
              testForm = (TestForm) super.formBackingObject(request);
              //THIS ALWAYS RETURNS NULL ON FORM SUBMISSION 
              List<TestObj> testList = testForm.getTestList();
           } else {
              //load initial data using hibernate. TestObj is hibernate domain object.
              List<TestObj> testList = myService.findTestList();
              testForm = new TestForm(testList);
           }
           return testForm;
        }

Here is my JSP snippet –

<form:form commandName="testForm" method="post">
   <c:forEach items="${testForm.testList}" var="testvar" varStatus="testRow">
     <tr>
       <td>
          <form:hidden path="testList[${testRow.index}].home" />
          <c:out value="${testvar.home}" />
    </td>
    <td>
      <form:input path="testList[${testRow.index}].destination" />
    </td>
     </tr>
   </c:forEach>
   <tr><td><input type="submit"></td></tr>
</form:form>

While the first time I load the data shows up fine on the form, when I press submit button the control goes to the formBackingObject method and the isFormSubmission returns true. However, when I get the command object using super.formBackingObject(request), it returns the form object with the testList value as null. I am unable to figure out why this simple case is not working?

I will really appreciate any help in getting this to work.

Answer 1

I guess my understanding of formBackingObject method must be wrong. I removed that method from the implementation, used referenceData for initial form load and onSubmit to process it on submit. This works fine and does get collection in the form back as expected.

Thanks all for the help though.