Manually-coded Relations between models

This is a simplifyed version of the previous question.
Here is my first simple situation again.
(I am using IdeaBlade DevForce 3.6.2.2)

1. State.
There are two objects in two models:

Model1.Location entity
  Id (PK, int)
  City
  Street
  House

Model2.Customer entity
  Id (PK, int)
  CompanyName
  LocationId (FK)

Model1 and Model2 stored in different modules or projects (say M1 and M2).
M2 project have reference to M1 assembly.

2. Task.
Link Customer entity to Location entity by LocationId field in manner of composition (1-1). It should be possible to easy get value of Customer` location property and make UI binding to it.

3. My first solution.

3.1 Add new Location property to Customer entity class:

        [RelationProperty("Customer_Location", QueryDirection.ParentQuery)]
        [BeforeSetValue]
        [AfterSetValue]
        public Model.Location Location
        {
            get
            {
                Model.Location result_;
                if (GetInterceptor<Location>("Location", GetLocationImpl, out result_)) return result_;
                return GetLocationImpl();
            }
            set
            {
                if (BeforeSetValue("Location", value))
                {
                    if (!SetInterceptor<Location>("Location", value, SetLocationImpl))
                    {
                        SetLocationImpl(value);
                    }
                    AfterSetValue("Location");
                }
            }
        }

        //Here is the main logic of subj.
        private Model.Location GetLocationImpl()
        {
            //Create dynamic relation
            EntityRelation relation = new EntityRelation(
                        new EntityColumn[] { Model.Location.IdEntityColumn },
                        new EntityColumn[] { Customer.LocationIdEntityColumn },
                        false,
                        "Customer_Location");
            Model.Location entity = GetParent<Location>(relation, this.PersistenceManager.DefaultQueryStrategy);
            if (entity.IsNullEntity)
            {
                //Create new Entity when it is not assigned
                entity = PersistenceManager.CreateEntity<Location>();
                //PersistenceManager.GenerateId(entity, Model.Location.IdEntityColumn);
                entity.AddToManager();
            }
            return entity;
        }

        private void SetLocationImpl(Location value)
        {
            if (value == null)
            {
                SetNull(this.LocationIdColumn);
            }
            else
            {
                SetColumnValue(this.LocationIdColumn, value, value.IdColumn);
            }
            OnPropertyChanged(new PropertyChangedEventArgs("Location"));
        }

3.2 Provide deletion of corresponding Location entity when delete Customer entity.
Customer class:
        public override void Delete()
        {
            Location.Delete();
            base.Delete();
        }

3.4. Provide right PersistenceOrder so Location entity will be inserted into DB before Customer.
  This may be done by filling SaveOptions/DefaultSaveOptions.PersistenceOrder for PersistenceManager.

4. Questions.

4.1. Whether my solution correct?
4.2. Where is the best place to implement automatic Customer.Location entity creation when creating new Customer entity (instead of creating on first call in GetLocationImpl())?
4.3. Is it necessary to implement step 3.4 or PersistenceManager will automatically determine right PersistenceOrder with help of RelationProperty attribute or something else?
4.4. Does new DevForce EF 4.0 have any advantages regarding cross-model relations definition?



Edited by vecs - 03-Jul-2008 at 10:44pm

I think that you are making things hard for yourself by creating two models (especially if you have bidirectional relationships between objects in the two different models).