Hi Ian, Not a direct answer to your question but:
I lost tons of time on jdo issue like yours where it gets very hard to understand and few explanations / docs available. I made some research and discovered Objectify: simple, efficient and as powerful as jdo with the same pojo annotation philosophy, I switched to it and will never go back because it works and I understand why it does or why it doesn't. Understand me: I really love App Engine but JDO/JPA are not my preferred feature ;-) regards didier On Nov 5, 4:31 pm, Ian Murdock <[email protected]> wrote: > Hi, > > I'm having a problem with embedded objects. > > My code looks something like this: > > @PersistenceCapable > public class Parent { > @PrimaryKey > @Persistent(valueStrategy=IdGeneratorStrategy.IDENTITY) > @Extension(vendorName="datanucleus", key="gae.encoded-pk", > value="true") > private String key; > > @Persistent > @Embedded > private Child child; > > public Child getChild() { > return child; > } > > public void setChild(Child child) { > this.child = child; > } > } > > @PersistenceCapable > @EmbeddedOnly > public class Child { > @Persistent > private String field; > > public Child(String field) { > this.field = field; > } > } > > With the code as above, I create an entity and persist it: > > Parent parent = new Parent(); > parent.setChild(new Child("foo")); > persistenceManager.makePersistent(parent); > > Looking at the data store, I see there's a property in Parent > called "field", and it has the value "foo" as expected. > However, when I read the Parent object back from the data > store, parent.getChild() returns null. If I remove the > @Embedded and @EmbeddedOnly annotations and add a key > to Child, parent.getChild() returns the child properly. > > Looking at the DataNucleus documentation [1], > I see there are "nullIndicatorColumn" and "nullIndicatorValue" > attributes to @Embedded, but setting e.g. > nullIndicatorColumn to "child" doesn't seem to have any effect > > Am I doing something wrong? > > [1]http://www.datanucleus.org/products/accessplatform/jdo/annotations.ht... > > -ian > -- > Ian Murdockhttp://ianmurdock.com/ > > "Don't look back--something might be gaining on you." --Satchel Paige -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
