Deferred delete and root objects

[Chicagoan2016]

When we call delete and Save on root objects (instead of immediate delete), the Save returns the same root object but with a status of IsNew. Is there a way we could set the root object as new and empty object? possibly by calling DataPorta.Create in the Dataportal delete method?

Kind Regards

[rockfordlhotka]

The data portal is returning the object as IsNew because you've deleted the data, so we have reason to believe that the object no longer reflects data in the database - therefore it is "new".

I'd recommend just ignoring the result of the save method and calling create from the client.

Another alternative to calling create on the client, is to rethink the UI/user workflow. Why are you even using the result of the save method at all, and does it make sense within the context of the user workflow?

Yet another alternative is in the server-side delete operation method, you could "blank" or clear all the properties in the object, so when the object is returned to the caller as being "new", it also contains only default values for the properties.

[rockfordlhotka]

Another solution would be, for this type, to use the data portal factory model, because then you have complete control over what is returned as the result of any operation, and so you could call the data portal to create a new instance and return it to the client.

[Chicagoan2016]

@rockfordlhotka I like the data portal factory model. So instead of void from factory method we will return the result of

DataPortal.Create<OurType>();

?

Regards

[rockfordlhotka]

Like this:

using Csla;
using Csla.Configuration;
using Csla.Core;
using Csla.Server;
using Microsoft.Extensions.DependencyInjection;
using MyCode;
using ObjectFactory = Csla.Server.ObjectFactory;

var services = new ServiceCollection();
services.AddCsla();
var serviceProvider = services.BuildServiceProvider();

var portal = serviceProvider.GetRequiredService<IDataPortal<PersonEdit>>();
var obj = portal.Fetch();
Console.WriteLine($"Id: {obj.Id}, Name: {obj.Name}, IsDeleted: {obj.IsDeleted}, IsNew: {obj.IsNew}");
obj.Delete();
Console.WriteLine($"Id: {obj.Id}, Name: {obj.Name}, IsDeleted: {obj.IsDeleted}, IsNew: {obj.IsNew}");
await obj.SaveAndMergeAsync();
Console.WriteLine($"Id: {obj.Id}, Name: {obj.Name}, IsDeleted: {obj.IsDeleted}, IsNew: {obj.IsNew}");

namespace MyCode
{
    [ObjectFactory(typeof(PersonEditFactory))]
    public class PersonEdit : BusinessBase<PersonEdit>
    {
        public static readonly PropertyInfo<int> IdProperty = RegisterProperty<int>(nameof(Id));

        public int Id
        {
            get => GetProperty(IdProperty);
            set => SetProperty(IdProperty, value);
        }

        public static readonly PropertyInfo<string> NameProperty = RegisterProperty<string>(nameof(Name));

        public string Name
        {
            get => GetProperty(NameProperty);
            set => SetProperty(NameProperty, value);
        }
    }

    public class PersonEditFactory(ApplicationContext applicationContext) 
        : ObjectFactory(applicationContext)
    {
        public PersonEdit Create()
        {
            var result = applicationContext.CreateInstance<PersonEdit>();
            MarkNew(result);
            return result;
        }
        
        public PersonEdit Fetch()
        {
            var result = applicationContext.CreateInstance<PersonEdit>();
            LoadProperty(result, PersonEdit.IdProperty, 1);
            LoadProperty(result, PersonEdit.NameProperty, "John Doe");
            MarkOld(result);
            return result;
        }

        public PersonEdit Update(PersonEdit obj)
        {
            PersonEdit result;
            if (obj.IsDeleted)
                result = DeleteSelf();
            else if (obj.IsNew)
                result = Insert(obj); 
            else
                result = DoUpdate(obj);
            return result;
        }
        
        private PersonEdit Insert(PersonEdit obj)
        {
            // Insert the object
            MarkOld(obj);
            return obj;
        }
        
        private PersonEdit DoUpdate(PersonEdit obj)
        {
            // Update the object
            MarkOld(obj);
            return obj;
        }

        private PersonEdit DeleteSelf()
        {
            var result = applicationContext.CreateInstance<PersonEdit>();
            MarkNew(result);
            return result;
        }
    }
}