ASP .NET core 3.0 依赖注入抛出 System.InsufficientExecutionStackException

Question

我对 NET 核心依赖项注入有一个奇怪的问题。当我尝试注册服务时，抛出 InsufficientExecutionStackException 异常。在这种情况下，这意味着什么？这就是我注册服务的方式（第三行抛出异常）：

        var connectionStr = Configuration.GetValue<string>("databaseConnectionString");
        services.AddSingleton<IDatabaseService>(s => new MySqlDatabaseService(connectionStr));
        services.AddSingleton<IUserService>(s => new UserService(s.GetRequiredService<IUserRepository>(), secret, s.GetRequiredService<IAchievementService>()));//this line throws the exception
        services.AddSingleton<IAchievementService, AchievementService>();
        services.AddSingleton<IUserRepository, UserRepository>();
        services.AddSingleton<IAchievementRepository, AchievementRepository>();
        services.AddSingleton<IUserRequestService, UserRequestService>();
        services.AddSingleton<AppSettingsService>();

UserService类中注入了两个服务。这些是那些的构造函数：

    public UserService(IUserRepository userRepository, string secret, IAchievementService achievementService)
    {
        this.achievementService = achievementService;
        this.userRepository = userRepository;
        this.secret = secret;
    }

用户存储库：

    public UserRepository(IDatabaseService databaseService)
    {
        this.databaseService = databaseService;
    }

成就服务：

        public AchievementService(IAchievementRepository achievementRepository, IUserService userService)
    {
        this.achievementRepository = achievementRepository;
        this.userService = userService;
        this.userRequestService = userRequestService;
    }

另一个奇怪的事情是，如果我从异常窗口中单击“查看详细信息”（我使用的是 Visual Studio 2019），调试器会崩溃并且不显示任何内容。

Answer 1

看起来您在UserService和之间有循环依赖AchievementService。dotnet 依赖注入不可能在UserService没有AchievementService. 但是要创建 的实例AchievementService，您需要一个 的实例UserService。所以你陷入了无限循环。

您应该尝试通过删除依赖项来避免这种情况。这两个服务真的需要依赖另一个吗？

如果不可能，您可以尝试使用Lazy<Service>而不仅仅是Service.

private readonly Lazy<IAchievementService> lazyAchievementService;

public UserService(Lazy<IAchievementService> lazyAchievementService, /*...*/)
{
    this.lazyAchievementService = lazyAchievementService;
    // ...
}

public void SomeFunction()
{
    var achievementService = lazyAchievementService.Value;
    achievementService.DoSomething();
}

这应该允许您创建两个类。