Question

我有一个Web API控制器，比如EmployeeController，我们使用Autofac进行注册。现在我们创建另一个具有相同名称和路由但具有不同功能的控制器。当我们尝试使用 Autofac 注册这个新的EmployeeController（即插件）时，我们会得到一个例外

找到了与名为EmployeeController的控制器匹配的多个类型。

我的目标是成功注入第二个控制器并用它覆盖第一个控制器的功能。

项目A - ＆gt;核心项目

namespace Main.API
{
    public class EmployeeController : ApiController
    {
        // Some Logic
    }    
}

项目B - ＆gt;插件项目

以后的消费者希望覆盖具有相同控制器名称的员工控制器

namespace Plugin.API
{
    public class EmployeeController : ApiController
    {
        // Some Logic
    }    
}

Autofac

// assemblies contains Main.API.dll & Plugin.API.dll
builder.RegisterApiControllers(assemblies.ToArray()).InstancePerRequest();

Answer 1

为了实现你想要的东西，我会使用AOP concept，这将使它更容易实现，更强大。

Castle DynamicProxy项目为.net提供了AOP概念， Autofac 可以使用Autofac.Extras.DynamicProxy2 nuget包。

您的主项目中只有1 EmployeeController

namespace Main.API
{
    public class EmployeeController : ApiController
    {
        public virtual String Get(Int32 id)
        {
           // Some Logic
        }
    }    
}

以及插件项目中的各种IInterceptor：

namespace Plugin 
{
    public class XEmployeeeControllerInterceptor : IInterceptor
    {
        public void Intercept(IInvocation invocation)
        {
            if(!invocation.Method.Name == nameof(Core.APi.EmployeeController.Get))
            {
                return; 
            }
            invocation.Proceed(); 

            // alter return value 
            invocation.ReturnValue = invocation.ReturnValue + "-intercepted";
        }
    }
}

然后注册这样的事情：

builder.RegisterApiControllers(assemblies.ToArray())
       .InstancePerRequest()
       .EnableClassInterceptors();

builder.RegisterAssemblyTypes(assemblies.ToArray())
       .As<IInterceptor>();

有关详细信息，请参阅Type Interceptors

Answer 2

使用以下代码段，您可以覆盖插件控制器的相同名称。

public class CustomHttpControllerSelector : DefaultHttpControllerSelector
    {
        private readonly HttpConfiguration _configuration;
        private readonly Lazy<Dictionary<string, HttpControllerDescriptor>> _controllers;


    /// <summary>
    /// custom http controllerselector
    /// </summary>
    /// <param name="config"></param>
    public CustomHttpControllerSelector(HttpConfiguration config) : base(config)
    {
        _configuration = config;
        _controllers = new Lazy<Dictionary<string, HttpControllerDescriptor>>(InitializeControllerDictionary);
    }

    /// <summary>
    /// GetControllerMapping
    /// </summary>
    /// <returns></returns>
    public override IDictionary<string, HttpControllerDescriptor> GetControllerMapping()
    {
        return _controllers.Value;
    }

    private Dictionary<string, HttpControllerDescriptor> InitializeControllerDictionary()
    {
        var controllers = new Dictionary<string, HttpControllerDescriptor>(StringComparer.OrdinalIgnoreCase);

        IAssembliesResolver assembliesResolver = _configuration.Services.GetAssembliesResolver();
        IHttpControllerTypeResolver controllersResolver = _configuration.Services.GetHttpControllerTypeResolver();
        ICollection<Type> controllerTypes = controllersResolver.GetControllerTypes(assembliesResolver);

        foreach (Type t in controllerTypes)
        {
            var controllerName = t.Name.Remove(t.Name.Length - DefaultHttpControllerSelector.ControllerSuffix.Length);

            //Remove Core API Controller and add the Plugin API controller.
            if (controllers.Keys.Contains(controllerName) && t.Namespace.Contains("Plugin"))
            {
                controllers.Remove(controllerName);
            }
            if (!controllers.Keys.Contains(controllerName))
            {
                controllers[controllerName] = new HttpControllerDescriptor(_configuration, t.Nam`enter code here`e, t);
            }
        }
        return controllers;
    }
}

如何允许插件webAPI覆盖现有的webAPI

2 个答案: