UniqueConstraint in EmbeddedConfiguration

Question

I just started using db4o in C #, and I had problems installing UniqueConstraint on the database ..

here is the db4o configuration

static IObjectContainer db = Db4oEmbedded.OpenFile(dbase.Configuration(), "data.db4o");
static IEmbeddedConfiguration Configuration()
{
    IEmbeddedConfiguration dbConfig = Db4oEmbedded.NewConfiguration();
    // Initialize Replication
    dbConfig.File.GenerateUUIDs = ConfigScope.Globally;
    dbConfig.File.GenerateVersionNumbers = ConfigScope.Globally;
    // Initialize Indexes
    dbConfig.Common.ObjectClass(typeof(DAObs.Environment)).ObjectField("Key").Indexed(true);
    dbConfig.Common.Add(new Db4objects.Db4o.Constraints.UniqueFieldValueConstraint(typeof(DAObs.Environment), "Key"));
    return dbConfig;
}

and object to serialize:

class Environment
{
    public string Key { get; set; }
    public string Value { get; set; }
}

every time I get some values, "The reference to the object is not installed in the instance of the object." A pop-up with a stack trace pointing to UniqueFieldValueConstraint is excluded. In addition, when I comment on two lines after the comment “Initialize indexes”, everything works fine (except for saving unique keys, which is a problem) ~

Commit Code (In case I do something wrong in this part too :)

public static void Create(string key, string value)
{
    try
    {
        db.Store(new DAObs.Environment() { Key = key, Value = value });
        db.Commit();
    }
    catch (Db4objects.Db4o.Events.EventException ex)
    {
        System.Console.WriteLine
            (DateTime.Now +  " :: Environment.Create\n" + ex.InnerException.Message +"\n" + ex.InnerException.StackTrace);
        db.Rollback();
    }
}

Help me please? Thanks in advance ~

Answer 1

, # :( :

// Initialize Indexes
dbConfig.Common.ObjectClass(typeof(DAObs.Environment))
    .ObjectField("<Key>k__BackingField").Indexed(true);
dbConfig.Common.Add(new Db4objects.Db4o.Constraints.
    UniqueFieldValueConstraint(typeof(DAObs.Environment), "<Key>k__BackingField"));

~ ^^