如何使用 caliburn micro 在 Wpf 中注入 EF DbContext

Question

我嘗試構建 WPF 應用程序通過 Entity 框架之上的 Repositories 與數據庫交互，我使用caliburn micro作為 MVVM 框架

問題是當我嘗試通過簡單容器在 ViewModels 中注入 Repertories 時，它不會實例化 My DbContext

存儲庫

public class UserRepo : IUserRepo
{
    private AppDb _ctx;

    public UserRepo(AppDb ctx)
    {
            _ctx = ctx;
    }
}

應用上下文

public class AppDb : DbContext
{
    public AppDb(DbContextOptions options) : base(options)
    {
    }

    public DbSet<User> Users { get; set; }
}

簡單容器上的配置

class Bootstrapper : BootstrapperBase
{

    private SimpleContainer _container = new SimpleContainer();
    private AppDb _db;
    public Bootstrapper()
    {
        Initialize();

        var options = new DbContextOptionsBuilder<AppDb>()
                      .UseSqlServer(@"Server=(localdb)\MSSQLLocalDB;Database=XRaySystem;Integrated Security=True;")
                      .Options;

        _db = new AppDb(options);
    }

    protected override void Configure()
    {
        _container.Instance(_container);

        _container
            .Singleton<IWindowManager, WindowManager>()
            .Singleton<IEventAggregator, EventAggregator>();
        //register the DataContext
        // i don't know how to add it
        _container.RegisterInstance(typeof(AppDb), null, _db); // <<<<<<<<<< how to add this correctly 
        //Register Reporisotries
        _container
            .PerRequest<IUserRepo, UserRepo>();
        //Register ViewModels
        GetType().Assembly.GetTypes()
            .Where(type => type.IsClass)
            .Where(type => type.Name.EndsWith("ViewModel"))
            .ToList()
            .ForEach(viewModelType => _container.RegisterPerRequest(
                viewModelType, viewModelType.ToString(), viewModelType));
    }
    protected override void OnStartup(object sender, StartupEventArgs e)
    {


        DisplayRootViewFor<DashBoardViewModel>();
        //base.OnStartup(sender, e);
    }

    protected override object GetInstance(Type service, string key)
    {
        return _container.GetInstance(service, key);
    }

    protected override IEnumerable<object> GetAllInstances(Type service)
    {
        return _container.GetAllInstances(service);
    }


    protected override void BuildUp(object instance)
    {
        _container.BuildUp(instance);
    }
}

查看 model

class DoctorViewModel : Screen
{
    private readonly IUserRepo _userRepo;

    public DoctorViewModel(IUserRepo userRepo)
    {
        _userRepo = userRepo;
    }
}

UserRepo已實例化，但使用 null AppDb

我的問題

如何配置 Simple Container 以將AppDb添加到UserRepo ？

我在 GitHub 上重現了同樣的問題

Answer 1

經過一番調試，我發現先運行Configure方法，然后調用構造函數！ 所以實例化是在 null 完成配置之后發生的

我通過在Configure方法本身中添加 _db 的實例化來解決它

class Bootstrapper : BootstrapperBase
{

    private SimpleContainer _container = new SimpleContainer();
    private AppDb _db;
    public Bootstrapper()
    {
        Initialize();
    }

    protected override void Configure()
    {
        var options = new DbContextOptionsBuilder<AppDb>()
                     .UseSqlServer(@"Server=(localdb)\MSSQLLocalDB;Database=XRaySystem;Integrated Security=True;")
                     .Options;

        _db = new AppDb(options); //<<<< solve the problem

        _container.Instance(_container);

        _container
            .Singleton<IWindowManager, WindowManager>()
            .Singleton<IEventAggregator, EventAggregator>();
        //register the DataContext
        _container.Instance(_db);
        // _container.RegisterInstance(typeof(AppDb), null, _db); 
        
         //Register Reporisotries
         _container
            .PerRequest<IUserRepo, UserRepo>();
        //Register ViewModels
        GetType().Assembly.GetTypes()
            .Where(type => type.IsClass)
            .Where(type => type.Name.EndsWith("ViewModel"))
            .ToList()
            .ForEach(viewModelType => _container.RegisterPerRequest(
                viewModelType, viewModelType.ToString(), viewModelType));
    }
    protected override void OnStartup(object sender, StartupEventArgs e)
    {

        DisplayRootViewFor<DashBoardViewModel>();
        //base.OnStartup(sender, e);
    }

    protected override object GetInstance(Type service, string key)
    {
        return _container.GetInstance(service, key);
    }

    protected override IEnumerable<object> GetAllInstances(Type service)
    {
        return _container.GetAllInstances(service);
    }


    protected override void BuildUp(object instance)
    {
        _container.BuildUp(instance);
    }
}