Anyone else trying to lazily load a parent-child relationship with
fds? The more I look at this the more I think it may be the key to
solving my problem.
I have some fundamental questions:
1. What *should* I return as the parent object on the child when I
return an object in response to an itemPendingError accessing the
children collection on the parent?
It seems crazy that I should look the parent up again and return a
fully populated object (the state may have changed in the client so
that would be wrong). If I send back a partially populated parent
object containing the identity I seem to get another itemPendingError
when I access the parent object, which I know I already have or I
wouldn't have the child! So that doesn't look right either.
Returning null means that my child contains a null parent, which is
also wrong.
2. After a commit I seem to get a repeat call to the original fill
method. Why? How can I avoid this? It is not logically correct for
me to be passing the parent layer of the lazily loaded objects back
again for a second time.
Anyone have any clues? Either I am doing something stupid (likely) or
bi-directional one-to-many does not work properly (less likely, but a
possibility). or maybe it works as intended but my understanding of
it is wrong.
Either way, I still have a pretty serious problem traversing backward
through my parent references in a graph of objects which ought to be
able to maintain itself. This problem remains unsolved.
Simon
--- In flexcoders@yahoogroups.com, "simonjpalmer" <[EMAIL PROTECTED]>
wrote:
>
> Pete / Jeff.
>
> I think I need to start from the basics here. I have been poring
> through endless logs but I have some unanswered questions at the
> beginning which I think I need to sort out first.
>
> The basic unanswered issue for me is that when I lazily load a child
> the parent reference is null. I never do anything to address this in
> code (i.e. I do not populate the parent object reference). Should I?
>
> Here is what my destinations look like (.'s for readability):
>
> <destination id="portfolio.spring">
> .<adapter ref="java-dao" />
> .<properties>
> ..<source>beanPortfolioAssembler</source>
> ..<factory>spring</factory>
> ..<metadata>
> ...<identity property="uid"/>
> ...<one-to-many property="planpoints" destination="planpoint.spring"
> lazy="true"/>
> ..</metadata>
> .</properties>
> </destination>
>
> <destination id="planpoint.spring">
> .<adapter ref="java-dao" />
> .<properties>
> ..<source>beanPlanPointAssembler</source>
> ..<factory>spring</factory>
> ..<metadata>
> ...<identity property="uid"/>
> ...<many-to-one property="parent" destination="portfolio.spring"
> lazy="true"/>
> ..</metadata>
> .</properties>
> </destination>
>
> Notice there is a bi-directional one-to-many relationship, both ends
> of which are defined as lazily loaded. My flex application has
> DataService object which is bound to portfolio.spring. I call the
> standard fill method supplying an ArrayCollection object to hold the
> results and the ID of the currently connected user:
>
> [Bindable] public var activePortfolios:ArrayCollection = new
> ArrayCollection();
>
> private var ds_po:DataService = new DataService("portfolio.spring");
>
> private function getPortfolios(authenticatedUser:User):void
> {
> ..ds_po.fill(activePortfolios, authenticatedUser.uid);
> }
>
> I have no client reference to planpoint.spring. On fill I populate
> and return a list of Portfolio objects. Each Portfolio object has a
> Set called "planpoints" which I populate with PlanPoint objects which
> are empty except for their uid. This means I do not send back a
> populated parent reference in the initial fill from portfolio.spring.
> I'm not sure whether that is correct or not. Can I rely on data
> services to wire that up correctly or should I be sending back a stub
> Portfolio object with its uid?
>
> Here is what my value objects look like. I am omitting most of the
> pojo code for brevity, all members are accessed by standard getters
> and setters. I have an equivalent set of AS objects on the flex side:
>
> public class Portfolio extends PojoBase implements IPojo
> {
> ...
> ..private String uid = new String();
> ..private Set<PlanPoint> planpoints = new HashSet<PlanPoint>();
> ...
> }
>
> public class PlanPoint extends PojoBase implements Serializable, IPojo
> {
> ...
> ..private transient Portfolio parent;
> ..private String uid = new String();
> ...
> }
>
> So on initial fill I have:
> PortfolioObject
> ..uid="XXX"
> ..planpoints
> ....PlanPointObject
> ......uid="YYY"
> ......parent=null
> ......everythingelse=null
>
> I then get server side calls through planpoint.spring when the lazy
> loading of the children kicks in. The getItem calls contain the uids
> of the partially populate objects that I returned on fill as expected.
> I then send back fully populated PlanPoint objects EXCEPT I never
> populate the parent. Not surprisingly when my PlanPoint arrives on
> the client side it has a null parent.
>
> PlanPointObject
> ..uid="YYY"
> ..parent=null
> ..everythingelse=something
>
> What should I be sending back? The back reference to the parent is
> lazily loaded accorinding to the definition of planpoint.spring above
> and the PlanPoint is being returned in response to an itemPendingError
> on the client side because a stub PlanPoint is being accessed in the
> context of a Portfolio. The Portfolios live in a managed collection.
> Should I reply to the planpoint.spring.getItem message with a
> PlanPoint object containing a stub Portfolio object with its uid
> populated?
>
> I think that until I make sure I have this part correct it is useless
> for me to look deeper into my issue.
>
> Am I doing the right thing here?
>
> As ever I really appreciate your help. This is currently standing
> between me and production code.
>
> Simon
>
