Registering a class and getting instance of the returned model using DRYIOC

Question

I want to register and get instance of current user in userviewmodel using DryIoc.Please how do i achieve this. This is the CurrentUserConfig class

public class CurrentUserConfig
{

    private IContainer _container;
    private UserViewModel _userViewModel;

    public CurrentUserConfig(IContainer container)
    {
        _container = container;
        _userViewModel = new UserViewModel();
    }

    public UserViewModel GetCurrentUser()
    {
        if (!string.IsNullOrEmpty(Thread.CurrentPrincipal.Identity.Name) && Thread.CurrentPrincipal.Identity.IsAuthenticated)
        {
            if (_userViewModel == null || _userViewModel.UserId < 1)
            {
                try
                {
                    var repository = _container.Resolve<IUserRepository>();
                    _userViewModel = Task.Run(async () => await repository.GetUserByUsername(Thread.CurrentPrincipal.Identity.Name)).Result;
                }
                catch (System.Exception ex)
                {
                    //return exception error;
                }
            }
        }

        return _userViewModel;
    }

}

This is what i want to achieve using DryIoc. This was done using SimpleInjector

        var currentUserConfig = new CurrentUserConfig(container);
        container.RegisterSingleton(currentUserConfig);

        container.Register<UserViewModel>(() =>
        {
            var objCurrentUserConfig = container.GetInstance<CurrentUserConfig>();

            return currentUserConfig.GetCurrentUser();
        }, Lifestyle.Scoped);

Answer 1

Direct translation would be:

var currentUserConfig = new CurrentUserConfig(container);
container.UseInstance(currentUserConfig);
container.RegisterDelegate<UserViewModel>(resolver =>
{ 
    var objCurrentUserConfig = resolver.Resolve<CurrentUserConfig>();
    return currentUserConfig.GetCurrentUser();
}, Reuse.InCurrentScope);

Alternatively you may register user config by type:

container.Register<CurrentUserConfig>(Reuse.Singleton);
container.RegisterDelegate<UserViewModel>(resolver => 
{ 
   var objCurrentUserConfig = resolver.Resolve<CurrentUserConfig>();
   return currentUserConfig.GetCurrentUser(); 
}, Reuse.InCurrentScope);

Note, that registering IContainer for user config is not required. DryIoc will automatically inject correctly scoped container instance.

There may be a further improvement to register user with DryIoc Made.Of construct. Made.Of enables registering with any instance or static class member returning the service. It is generally better than RegisterDelegate because DryIoc may analyse the service creation, and warn you about captive or recursive dependencies.

container.Register<CurrentUserConfig>(Reuse.Singleton);
container.Register<UserViewModel>(
    Made.Of(_ => ServiceInfo.Of<CurrentUserConfig>(), config => config.GetCurrentUser()),
    Reuse.InCurrentScope);