Andres’ Tech Blog

Focusing on java technologies.

Using Objectify Alongside JDO

When migrating from JDO to Objectify, It’s often the case where you need them to co-exist during the transition. Here is my case:

Suppose that you have an entity called UserProfile defined as follows:

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@PersistenceCapable
public class UserProfile implements Serializable {

    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    private Key key;
    @Persistent
    public String photoPath;
    @Persistent
    public String userNickname;
}

A pretty normal JDO-annotated entity. Now reading on-line people say that Ofy and JDO can co-exist. So I tried something like:

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

    @Id
    public Long oid;

    @Persistent
    public String photoPath;
    @Indexed
    @Persistent
    public String userNickname;
}

Notice that I’m explicitly ignoring the key. However I get the following vey cryptic exception:


java.lang.NoClassDefFoundError: Could not initialize class com.x.model.OfyService

The solution I found was to leave UserProfile intact and create a new class:

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@Entity(name="UserProfile")
public class UserProfileOfy implements Serializable {
    @Id
    public Long oid;

    public String photoPath;
    @Indexed
    public String userNickname;
}

Notice the name parameter in the @Entity annotation.