Question

I have a GAE app that uses the java.util.Calendar class.
My app changes some internal data when a day passes/
Currently I want to test the app, so I have a fake date data-member that I set and modify manually.
I want to save it to the datastore.
After about 2 hours of trying to save it, I decided to wrap it in a class I named FakeDate. it looks like this:

@PersistenceCapable
public class FakeDate {

@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;

@Serialized
private Calendar _fakeCurrentDate;

The only problem is, the data of the _fakeCurrentDate is not saved.
At first I set the Calendar date to be 8/8/2012
When I call

pm.makePersistent(_currentDate);

It looks like everything is ok, but when I call

        PersistenceManager pm = PMF.get().getPersistenceManager();
    Query q = pm.newQuery(FakeDate.class);
    try {
        @SuppressWarnings("unchecked")
        List<FakeDate> list = (List<FakeDate>) q.execute();
        for (FakeDate f:list){
            System.out.println(f.getDayOfMonth());
            System.out.println(f.getMonth());
            System.out.println(f.getYear());
        }
    } finally {
        q.closeAll();
        pm.close();
    }

The FakeDate instance I get holds a Calendar instance of the date 27/9/2012. This is the default date I get when calling Calendar.getInstance()

It looks like I am missing something pretty easy.
Am I?

Answer 1

Calendar class is not a supported field type for a datastore model. For details for the supported types take a look at Properties and Value Types. If you need to have a Date field in your model, declare it as java.util.Date and initialize it by using Calendar.

Hope this helps!