Jeff, You mentioned that there is a tool that will automatically generate data-management-config.xml from a hibernate configuration. Is this tool available yet and if so where can I get it?
Thanks! Andrew The University of Iowa --- In [email protected], "Jeff Vroom" <[EMAIL PROTECTED]> wrote: > > Hi Greg, > > > > Sorry for the delay in my response. > > > > I think typically when you are using a managed association in LC DS you > do not want to set any cascade operations like "merge" and "persist". > This is especially true in 2.5.1 where cascade="save-update" (at least) > caused problems when using managed associations. > > > > I am a little worried about the servlet filter which keeps the session > open. I think for remote object that approach might work fine but for > data management, it is opening and closing its own session so not sure > how that would interact with your global session. > > > > One thing I noticed is that you have "parent" properties with > lazy="false". That can be scary because it can end up pulling in a > lot more of the model than you intend through that association. I > usually recommend that parent always have lazy="true". > > > > Also, just to let you know the 2.6 beta is on labs.adobe.com and so you > might want to give that a shot. It will generate the metadata section > of the data-management-config.xml automatically from the hibernate > configuration so that makes it easier to get started. > > > > In terms of the cascade settings, when you declare a managed association > in LC DS for an association in hibernate, normally we do not require any > cascade options enabled. I would like the assembler to not care if you > do but unfortunately in 2.5.1 there is a bug when you set save-update > (at least). I do have a fix for that problem but it did not make it > into beta 2. If you do get on 2.6 and would like to try out the fix, > drop me an email at [EMAIL PROTECTED] and I'll send you the jar. > > > > Jeff > > > > ________________________________ > > From: [email protected] [mailto:[EMAIL PROTECTED] On > Behalf Of gordon_greg > Sent: Wednesday, April 09, 2008 9:00 AM > To: [email protected] > Subject: [flexcoders] Re: Flex DataService problem: unexpected > "unsubscribe" and "release collection" > > > > Again, many thanks as this thread is shedding much needed light on my > world. > > I'm planning on spending my day working through my Hibernate/LCDS > settings, focusing on defining all bi-directional relationships and > Hibernate cascading... > > In reviewing this thread I notice in your last response a bit of an > inconsistency from a previous response: > > on April 8 you mentioned: > > Hibernate has an option called cascade="save-update".... This > option is always true by default with LC DS. > > This was in reference to adding a new item to a managed collection that > is a bi-directional association. > > However, last night you also mentioned: > > With hierarchical values you need to use cascade="save-update" since > then it becomes the responsibility of the parent to save the child. > Unfortunately in 2.5.1 save-update can break a managed association so > you use save-update with no association and don't use it when you do > have one. > > My current understanding is that I should define all bi-directional > assocations in LCDS the same as I have in Hibernate, since I do NOT want > them treated as Hierarchical values, and as such I'm guessing from your > last post that I should NOT declare cascade="save-update" in the parent > classes, is this correct? > > Perhaps we should just use a concrete example and get it over with ;) > > Bear with me... > > Let's say we want to represent a tree of items and groups, and for > simplicity we'll say that an item will only belong to a single group, a > group can have subgroups, and that we want to yield cascading deletes > when deleting a group. (And finally that we want all collections > lazy-loaded!) > > Our SQL tables look like: > > Group > - id:integer > - parent_id:integer > - name:varchar(25) > > Item > - id:integer > - group_id:integer > - name:varchar(25) > > Our annotated Hibernate classes: > > ------------------------------ START: my.models.Group.java > ------------------------------ > > @Entity > > @Table( name="Group") > > public class Group { > > > > private Integer id; > > private String name; > > private Group parent; > > private List<Group> subGroups; > > private List<Item> items; > > > > @Id > > @GeneratedValue(strategy=GenerationType.AUTO) > > public Integer getId(){ return id; } > > public void setId(Integer id) { > > this.id = id; > > // due to problems with LCDS passing up 0's instead of nulls, I > detect this on my own... > > if (id != null && id.intValue() == 0) this.id = null; > > } > > > > public String getName(){ return name; } > > public void setName(String name){ this.name = name; } > > > > @ManyToOne() > > @JoinColumn(name="parent_id", nullable=true, insertable=true, > updatable=true) > > public Group getParent() { return parent; } > > public void setParent(Group parent) { this.parent = parent; } > > > > @OneToMany(mappedBy="parent", fetch = {FetchType.LAZY}, > cascade = {CascadeType.PERSIST, > CascadeType.MERGE}) > > @Cascade({org.hibernate.annotations.CascadeType.DELETE_ORPHAN}) > > public List<Group> getSubGroups() { return subGroups; } > > public void setSubGroups(List<Group> subGroups) { this.subGroups = > subGroups; } > > > > @OneToMany(mappedBy="group", fetch = {FetchType.LAZY}, > cascade = {CascadeType.PERSIST, > CascadeType.MERGE}) > > @Cascade({org.hibernate.annotations.CascadeType.DELETE_ORPHAN}) > > public List<Item> getItems() { return items; } > > public void setItems(List<Item> items) { this.items = items; } > > } > > ------------------------------ END: my.models.Group.java > ------------------------------ > > ------------------------------ START: my.models.Item.java > ------------------------------ > > @Entity > > @Table( name="Item") > > public class Item { > > > > private Integer id; > > private String name; > > private Group group; > > > > @Id > > @GeneratedValue(strategy=GenerationType.AUTO) > > public Integer getId(){ return id; } > > public void setId(Integer id) { > > this.id = id; > > // due to problems with LCDS passing up 0's instead of nulls, I > detect this on my own... > > if (id != null && id.intValue() == 0) this.id = null; > > } > > > > public String getName(){ return name; } > > public void setName(String name){ this.name = name; } > > > > @ManyToOne() > > @JoinColumn(name="group_id", nullable=true, insertable=true, > updatable=true) > > public Group getGroup() { return group; } > > public void setGroup(Group group) { this.group = group; } > > } > > ------------------------------ END: my.models.Item.java > ------------------------------ > > And finally our DataService destinations: > > ------------------------------ START destinations > ------------------------------ > <destination id="spring.group"> > > <adapter ref="java-dao"/> > > <properties> > > <scope>application</scope> > > <source>groupAssemblerBean</source> > > <factory>spring</factory> > > <item-class>my.models.Group</item-class> > > <metadata> > > <identity property="id" undefined-value="0"/> > > <many-to-one property="parent" > destination="spring.group" lazy="false"/> > > <one-to-many property="subGroups" > destination="spring.group" lazy="true"/> > > <one-to-many property="items" destination="spring.item" > lazy="true"/> > > </metadata> > > <network> > > > <subscription-timeout-minutes>0</subscription-timeout-minutes> > > <reconnect fetch="INSTANCE"/> > > </network> > > </properties> > > </destination> > > > > <destination id="spring.item"> > > <adapter ref="java-dao"/> > > <properties> > > <scope>application</scope> > > <source>groupAssemblerBean</source> > > <factory>spring</factory> > > <item-class>my.models.Group</item-class> > > <metadata> > > <identity property="id" undefined-value="0"/> > > <many-to-one property="group" destination="spring.group" > lazy="false"/> > > </metadata> > > <network> > > > <subscription-timeout-minutes>0</subscription-timeout-minutes> > > <reconnect fetch="INSTANCE"/> > > </network> > > </properties> > > </destination> > > ------------------------------ END destinations > ------------------------------ > > Now, notice that I'm using Spring as well as Hibernate, so I've followed > the examples online to use the Spring factory, and because I've got lazy > loaded collections and need to force the Hibernate session to stay open, > I've routed LCDS to have all traffic flow through a single "spring" > servlet, and that servlet in turn has all of the usual "flex" servlets > defined as controllers, and I'm using Spring's > openSessionInViewInterceptor to keep the Hibernate session open. > > I realize this may create some differences that actually matter to LCDS, > but what I'm looking for in this post is whether I have the right idea > in how I've configured the associations between Flex and Hibernate, and > specifically if the Cascade values look right for interacting with LCDS. > > I also realize that since I'm not specifically declaring the use of the > HibernateAssembly in my destinations, and because I'm using annotations, > I'm guessing it's possible that LCDS is not able to "read" the Hibernate > configuration properly, although I also have no idea whether this really > matters. I also don't know that it matters that I'm not specifying a > <hibernate-entity> element... > > Anyway, if you've read this much I surely appreciate you taking your > time on this! > > Many thanks, > > Greg >
