How to instert child entities in JDO (Google App Engine) ?

Question

How do i add a record to a child entity in the example below ? For example i have a Employee Record which is name is "Sam". how do i add 2 street adress for sam ?

Guess i have a

The Parent entity is Employee

import java.util.List;

// ...
@Persistent(mappedBy = "employee")
private List<ContactInfo> contactInfoSets;

The Child key is Adress

import com.google.appengine.api.datastore.Key;
// ... imports ...

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

    @Persistent
    private String streetAddress;

    // ...
}

Answer 1

It just works:

Employee sam = new Employee("Sam");
List<Address> addresses = new ArrayList<Address>();
addresses.add(new Address("Foo St. 1"));
addresses.add(new Address("Bar Bvd. 3"));
sam.setAddresses(addresses);
persistenceManager.makePersistent(sam);

Employee being:

@PersistenceCapable(identityType = IdentityType.APPLICATION, detachable = "true")
public class Employee {
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    private Key key;
    private List<Address> addresses;
    ...
}

Address being:

@PersistenceCapable(identityType = IdentityType.APPLICATION, detachable = "true")
public class Address {
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    private Key key;
    ...
}

Use @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable = "true") as the class level annotation. Usually you don't need to annotate any other fields but the key, so the @Persistent(mappedBy = "employee") on the List is unnecessary.

Btw. I suggest using parametrized collections.

Answer 2

Hello, gwt client needs the source code. So if you use a Key, GWT will complain. Have you got another detailed solution for relationship 1/N without a Key class ?