CMR / CMP Fields should not be read-only
----------------------------------------

         Key: GERONIMO-675
         URL: http://issues.apache.org/jira/browse/GERONIMO-675
     Project: Geronimo
        Type: Bug
  Components: OpenEJB  
    Versions: 1.0-M4    
 Environment: Windows
    Reporter: Matt Hogstrom


> On 14/06/2005 12:42 PM, Matt Hogstrom wrote:
> 
>>I have a typical bean sequence where there is an Order and a number of Order 
>>Lines.  (1 ... many)  The OrderEnt is created from a Session bean 
>>coincidentally named OrderSes.  The OrderEnt then in ejbPostCreate creates 
>>the appropriate OrderLines.  Here is the code from OrderEnt:
>>
>>    public void ejbPostCreate(OrderDataBean odb, boolean deferred) 
>>    throws CreateException {
>>  
>>
> <snip>
> 
>>Depending on the situation one of the above orderLineHome.create methods is 
>>invoked.  So far, so good.
>>
>>In the OrderLineEnt.create method things go a bit wrong. Here is the stack 
>>trace:
>>
>>Caused by: javax.ejb.EJBException: cmp-field [orderId] is read-only.
>>        at 
>> org.tranql.ejb.ReadOnlyCMPFieldAccessor.set(ReadOnlyCMPFieldAccessor.java:44)
>>        at org.openejb.entity.cmp.CMPSetter.invokeInstance(CMPSetter.java:74)
>>        at 
>> org.openejb.entity.cmp.CMPMethodInterceptor.intercept(CMPMethodInterceptor.java:75)
>>  
>>
> Based on this stack-trace, I confirm that the CMP field orderId is 
> mapped to a foreign key.
> 
>>Here is the ejbCreate method that is failing
>>
>>     public OrderLineEntPK ejbCreate(int id, Integer orderId, String itemId, 
>> int quantity, BigDecimal totalValue, 
>>              int olineStatus, java.sql.Date shipDate, BigDecimal msrp) 
>> throws CreateException {
>>
>>        if( debugging )
>>            debug.println(3, "ejbCreate of ol_id = " + id + ", o_id = "
>>                          + orderId);
>>
>>        setId(id);
>>        setOrderId(orderId);                          <==================== 
>> This is the line that is failing.
>>        setItemId(itemId);
>>        setQuantity(quantity);
>>        setTotalValue(totalValue.setScale(2, BigDecimal.ROUND_UP));
>>        setOlineStatus(olineStatus);
>>
>>
>>
>>OrderId is the FK to the Order.  
>>  
>>
> Fields mapped to foreign key columns are read-only. They are read-only 
> for the following reason:
> Let's assume that:
> * we have one existing line item lineItemEntity;
> * lineItemEntity is already related to an order orderEntity;
> * orderEntity is related to two line items, lineItemEntity (as expected) 
> and lineItemEntity2;
> * we want to relate lineItemEntity to a new order orderEntity2;
> * orderEntity2 is related to zero line items; and
> * line item defines a CMR field order to set its related order.
> 
> In this specific scenario, if we set the CMR field order of 
> lineItemEntity to orderEntity2, then:
> * orderEntity2 is now related to the line item lineItemEntity; and
> * orderEntity is now related to only one line item lineItemEntity2.
> 
> In this same scenario, if we set the CMP field orderId of lineItemEntity 
> to the primary key of orderEntity2, then I am not sure of what the 
> result should be. Indeed, it is a CMP field and no specfic semantic is 
> attached to it.
> 
> To some extent, I am not sure that we should allow developers to update 
> relationships via a direct update to the underlying foreign key columns. 
> We could implement a fix to have a CMR semantic for CMP fields mapped to 
> foreign ley columns; yet it does not sound good. Having said that, I do 
> not have a strong opinion and I am happy to support such a scenario, if 
> we need to.
> 
> Also, it is worth to notice that such a potential fix will only be able 
> to handle CMP having simple primary keys. CMP having compound primary 
> keys will still have a read-only approach.
> 
>>First question is the deployment right for this scenario?  If it is, then I 
>>think that the container is not acting correctly.  This code runs on 
>>WebLogic, Sun One, WebSphere, etc.
>>  
>>
> Do you know if they properly support such scenarii (the CMP field must 
> have a CMR semantic)? Also, do you know if they do not allow such 
> scenarii in the case of compound PK CMP?
> 
> Thanks,
> Gianny

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