c# - (接口(interface))检测到类型服务的循环依赖

Question

我有 2 个接口(interface):

public interface IPedidoService
{
    UsuarioDrogueria CUsuarioDrogueria(string userId, int idDrogueria);
    List<PedidoComboProducto> CPedidosCombosProductos(int idcombo, int idPedido);  
} 

public interface IEmailService
{
    void SendEmailAttachment(string email, string subject, string archive);
    void SendNotificationEmail(List<Pedido> pedidos, string email, Drogueria drog);
    void SendNotificationEmailADM(Pedido pedido) ;
}

我想在 IPedidoService 中使用 IEmailService 的函数，所以我在创建存储库时将它注入(inject)到它的构造函数中。

public class PedidoService : IPedidoService
{
    private readonly IEmailService emailService;

    public PedidoService(IEmailService e)
    {
        this.emailService = e;
    }
}

到这里为止一切正常，但是当我尝试反转角色时(IEmailService 中的IPedidoService 函数):

public class EmailService : IEmailService
{
    private readonly IPedidoService pedidoSettings;

    public EmailService(IPedidoService p)
    {
        this.pedidoSettings = p;
    }
}

我最终得到这个异常:

System.InvalidOperationException: A circular dependency was detected for the service of type
   'EnvioPedidos.Data.Abstract.IPedidoService'.
    EnvioPedidos.Data.Abstract.IPedidoService(EnvioPedidos.PedidoService) ->
    EnvioPedidos.Data.Abstract.IEmailService(EnvioPedidos.EmailService) ->
    EnvioPedidos.Data.Abstract.IPedidoService

谁能帮我追踪这里的问题？

Answer 1

一个简单的方法是使用 Lazy<T>基于此 blog 的类:

自定义扩展方法:

public static class LazyResolutionMiddlewareExtensions
{
    public static IServiceCollection AddLazyResolution(this IServiceCollection services)
    {
        return services.AddTransient(
            typeof(Lazy<>),
            typeof(LazilyResolved<>));
    }
}

public class LazilyResolved<T> : Lazy<T>
{
    public LazilyResolved(IServiceProvider serviceProvider)
        : base(serviceProvider.GetRequiredService<T>)
    {
    }
}

在 Startup.cs 中配置:

public void ConfigureServices(IServiceCollection services)
{           
    //services.AddSingleton<IPedidoService, PedidoService>();
    //services.AddSingleton<IEmailService, EmailService>();

    services.AddLazyResolution();
}

更改您的工具类:

public class PedidoService : IPedidoService
{
    private readonly Lazy<IEmailService> emailService;

    public PedidoService(Lazy<IEmailService> e)
    {
        this.emailService = e;
    }

    //...
}
public class EmailService : IEmailService
{
    private readonly Lazy<IPedidoService> pedidoSettings;

    public EmailService(Lazy<IPedidoService> p)
    {
        this.pedidoSettings = p;
    }
    //...
}