[appengine-java] Using entity.setProperty on one-to-many relationships

[Kalyan Akella]

Hi,

In my application, I have the following unidirectional one-to-many 
relationship:

@PersistenceCapable
public class Recipe implements Serializable {
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    private Key key;

    @Persistent
    private String name;
    ....
}

@PersistenceCapable
public class CookBook {
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    private Key key;

    @Persistent
    private String title;

    @Persistent
    private List<Recipe> recipes;    // *<- one to many with Recipe *
    ....
}

I am doing the following to persist an instance of *CookBook* into data 
store using the low level API:

    private DatastoreService dataStoreSvc = 
DatastoreServiceFactory.getDatastoreService();

    public void persistEntity(CookBook cookBook) {
        Entity entityToPersist = new Entity("CookBook");
        ...
        entityToPersist.setProperty("recipes", cookBook.getRecipes());  // *<-- 
an error occurs here*
        ...
        dataStoreSvc.put(entityToPersist);
    }

In the snippet above, the highlighted line throws the following error:

recipes: com.examples.domain.Recipe is not a supported property type.
java.lang.IllegalArgumentException: recipes: com.examples.domain.Recipe is 
not a supported property type.
    at 
com.google.appengine.api.datastore.DataTypeUtils.checkSupportedSingleValue(DataTypeUtils.java:184)
    at 
com.google.appengine.api.datastore.DataTypeUtils.checkSupportedValue(DataTypeUtils.java:149)
    at 
com.google.appengine.api.datastore.DataTypeUtils.checkSupportedValue(DataTypeUtils.java:123)
    at 
com.google.appengine.api.datastore.Entity.setProperty(Entity.java:280)
    at 
com.examples.domain.persist.DatastoreHelper.persistEntity(DatastoreHelper.java:21)

Note that I marked the *Recipe* class to be Serializable & 
PersistanceCapable. Still the *setProperty* call fails. Moreover, I am using 
this snippet of code (and the low level API) during local unit testing and 
my test fails with this error.

Could you please help me understand what am I missing here ? Please let me 
know if you need more information.
Sincere Regards,
Kalyan

-- 
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 google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.