c# - 使用 Unity 解决通用 Microsoft.Extensions.Logging.ILogger - 获取 InvalidCastException

Question

我正在尝试在 Unity(版本 4)中注册一个通用 ILogger(来自 Microsoft.Extensions.Logging，而不是来自 Serilog)。

我有以下类(class):

public class MyClass
{
    private readonly Microsoft.Extensions.Logging.ILogger<MyClass> _logger;

    public MyClass(Microsoft.Extensions.Logging.ILogger<MyClass> logger)
    {
        _logger = logger;
    }
}

以及以下 Unity 注册和测试:

// Arrange
IUnityContainer container = new UnityContainer();

// provider from Serilog.Extensions.Logging nuget package
var provider = new Serilog.Extensions.Logging.SerilogLoggerProvider();

container.RegisterType(typeof(Microsoft.Extensions.Logging.ILogger<>),
    new InjectionFactory((ctr, type, name) =>
    {
        var loggerType = type.GetGenericArguments()[0].FullName;
        Microsoft.Extensions.Logging.ILogger logger = provider.CreateLogger(loggerType);
        return logger;
    }));

container.RegisterType<MyClass, MyClass>(); // just for demo purpose. 

// Assert
container.Resolve<MyClass>();

这对我来说似乎没问题，太糟糕了，我在解决时遇到以下错误:

Exception is: InvalidCastException - Unable to cast object of type 'Serilog.Extensions.Logging.SerilogLogger' to type 'Microsoft.Extensions.Logging.ILogger`1[MyNamespace.MyClass]'.

如何解决这个问题？

完全异常:

Microsoft.Practices.Unity.ResolutionFailedException: Resolution of the dependency failed, type = "MyNamespace.MyClass", name = "(none)". Exception occurred while: Resolving parameter "logger" of constructor MyNamespace.MyClass(Microsoft.Extensions.Logging.ILogger1[[MyNamespace.MyClass, MyNamespace.Infra.UnitTests, Version=1.0.0.0, Culture=neutral, PublicKeyToken=edbaf8e9a324553f]] logger).
Exception is: InvalidCastException - Unable to cast object of type 'Serilog.Extensions.Logging.SerilogLogger' to type 'Microsoft.Extensions.Logging.ILogger1[MyNamespace.MyClass]'.

更新

当使用 Microsoft.Extensions.DependencyInjection 时，这有效:

// Arrange
var serviceCollection = new Microsoft.Extensions.DependencyInjection.ServiceCollection()
    .AddLogging(builder => builder.AddSerilog())
    .AddTransient<MyClass, MyClass>();

var serviceProvider = serviceCollection.BuildServiceProvider();

// Assert
serviceProvider.GetService<MyClass>();

所以我尝试使用 Unity 而不是 Microsoft.Extensions.DependencyInjection 来实现这一点

不幸的是，Unity 没有 AddSerilog，我必须使用 Unity

Answer 1

我发现的最简单的方法是注册一个工厂并反射(reflect)他们的扩展方法来做到这一点并获得正确的响应类型。此示例还期望您已注册一个 ILoggerFactory。

_container = new UnityContainer();
_container.RegisterInstance<ILoggerFactory>(new LoggerFactory().AddLog4Net(), new ContainerControlledLifetimeManager());
_container.RegisterFactory(typeof(ILogger<>), null, (c, t, n) =>
        {
            var factory = c.Resolve<ILoggerFactory>();
            var genericType = t.GetGenericArguments().First();
            var mi = typeof(Microsoft.Extensions.Logging.LoggerFactoryExtensions).GetMethods().Single(m => m.Name == "CreateLogger" && m.IsGenericMethodDefinition);
            var gi = mi.MakeGenericMethod(t.GetGenericArguments().First());
            return gi.Invoke(null, new[] { factory });
        });