Binding 1-N relations

[Kei]

I defined Orders which contains a Collection of OrdersDetail. Trying to update both Orders and related OrdersDetail in a single form:

<form name="ordersMaintainForm" method="post" action="<c:url value="/orders/viewOrders.htm"/>">
	<spring:nestedPath path="orders">
		<table width="90%" align="center">
			<tr>
				<td>Orders Id</td>
				<td>
					<c:out value="${orders.ordersId}"/>
					<spring:bind path="ordersId">
						<input type="hidden" name="ordersId" value="<c:out value="${orders.ordersId}"/>"/>
					</spring:bind>
				</td>
			</tr>
			<tr>
				<td>Status</td>
				<td>
					<spring:bind path="status">
						<input type="text" name="status" value="<c:out value="${orders.status}"/>"/>
					</spring:bind>
				</td>
			</tr>
			<c:forEach var="od" items="${orders.ordersDetails}" varStatus="loopStatus">
				<spring:bind path="ordersDetails[${loopStatus.index}].itemId">
					<input type="text" name="<c:out value="${status.expression}"/>" value="<c:out value="${status.value}"/>"/>
				</spring:bind>
			</c:forEach>
	</table>
	</spring:nestedPath>
</form>

I manage to show the form with correct values. But when I submit the form, before arriving onSubmit, "Data binding errors: 1" was shown in log and the system jumped back to the form.

If I tried commenting out the ordersDetails part, the form is submittable.

I've tried adding the <spring:hasBindErrors> and activating log4j.logger.org.springframework=DEBUG, myLog. Both show nothing.

How could I debug it?
and is it appropriate to try maintaining a 1-N relations in this way?

[sethladd]

Is there actually a non-null object inside orders.getOrdersDetails().get(0) ? The objects inside your collection can't be null (although the properties on the objects inside the collection can be null).

[Kei]

I've init all the collections inside, and the form could be displayed with correct Orders and OrdersDetail values.

I got the binding error when I tried submitting the form.

I'm wondering is there special handling to instantiate a form object with collection inside...

[sethladd]

I'm wondering is there special handling to instantiate a form object with collection inside...

Not really. Are you using a session form? Are you using Hibernate? Where do you load the object (inside formBackingObject()?)

It might help to post your controller code, including the XML bean definition for it.

[Kei]

You are right. I should use a session form.

Once I add the setSessionForm(true) into the controller constructor, it works fine now.

Thx a lot.