Hi Carl, You can use a string-encoded key on the child object to avoid a dependency on proprietary google classes. More info here: http://code.google.com/appengine/docs/java/datastore/creatinggettinganddeletingdata.html#Keys
(search for Key as Encoded String)
Hope this helps,
Max
On Fri, Jan 15, 2010 at 6:24 AM, Carl Ballantyne
<carlballant...@gmail.com>wrote:
> Hi All,
>
> I have two classes, a Parent and a Child. (See below for code) The
> Parent class contains a reference to a Child instance. However when I
> try and save a Parent instance I get the following error: Cannot have
> a java.lang.Long primary key and be a child object.
>
> The error is clear enough and upon searching around I have found the
> solution is to convert the primary key of my Child class to Key.
> However this just does not sit well with me that I have to modify my
> domain classes with proprietary google classes to suit the datastore.
> Is there no other way to do this without resorting to custom APIs at
> the domain level? Or is this a limitation of JDO and I need to do a
> bit more research?
>
> Cheers,
> Carl.
>
> @PersistenceCapable(identityType = IdentityType.APPLICATION)
> public class Parent {
>
> @PrimaryKey
> @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> private Long id;
> @Persistent
> private String name;
>
> @Persistent
> private Child child;
>
> public Long getId() {
> return id;
> }
> public void setId(Long id) {
> this.id = id;
> }
> public String getName() {
> return name;
> }
> public void setName(String name) {
> this.name = name;
> }
> public Child getChild() {
> return child;
> }
> public void setChild(Child child) {
> this.child = child;
> }
>
>
> }
>
>
>
> @PersistenceCapable(identityType = IdentityType.APPLICATION)
> public class Child {
>
> @PrimaryKey
> @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> private Long id;
> @Persistent
> private String name;
>
>
> public Long getId() {
> return id;
> }
> public void setId(Long id) {
> this.id = id;
> }
> public String getName() {
> return name;
> }
> public void setName(String name) {
> this.name = name;
> }
>
> }
>
>
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