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I am using db4o 7.2 for .NET 3.5. I save some data, call Close(). The data file keeps it size but all queries return empty collections after calling db.Close() I AM calling db.Commit() after storing the objects. Is this really possible? I'd like to experiment with db4o but I'm stuck.

IObjectContainer db = Db4oFactory.OpenFile(dbFileName);

StoreFirstCar(db); // from tutorial

db.Commit();

db.Close();

db = Db4oFactory.OpenFile(dbFileName);

IList cars = db.Query<Car>();

int count = cars.Count; // count is 0 !

inv:

IList cars = db.Query<Car>();

This looks strange... usually (for me as a Java-db4o-user) a call to #query() without any parameters creates an SODA-Query-Object, which is something completely different than executing a query which should give you an ObjectSet.

So I would recommend to use something like:

IList cars = db.Query<Car>(typeof(Car));

HTH, Maik 

If I understood the tutorial correctly, my objects are stored in the .yap-File.
I tried the examples from the tutorial and stored some pilots in the Container.

Now I wrote my own ConsoleApplication and wanted to read the stored pilots from the file with:

// accessDb4o
IObjectContainer mydb = Db4oFactory.OpenFile("C:/Temp/test.yap");
            try
            {
                // retrieveAllPilots
                result = mydb.QueryByExample(typeof(Pilot));
                ListResult(result);
               
                Console.ReadLine();
            }

            finally
            {
                mydb.Close();
            }

 
However I always get an empty output, lilke: 0 0

which absically means that thgere are no objects in the container.  :(

Did I do something wrong?