Is it possible to have a computed property on Google App Engine using Java?

Question

I have an app engine application and I want to run a query that sorts the result based on a expression involving two properties. Best way I thought of doing it so far is to

Answer 1

Compute your value in an @OnSave method:

@Entity
public class YourEntity {
    @Id Long id;

    String foo;
    String bar;

    @Index String computed;

    @OnSave void computeComputed() {
        computed = // synthesize from foo and bar
    }
}

This is what NDB's ComputedProperty actually does. Java doesn't really have a way of matching that syntax, and I'm not sure NDB's approach is any more elegant. Just leave off the setter method for computed.