无法在控制器“controller”上调用操作方法“system.web.mvc.partialView result foo[t](t)”,因为该操作方法是通用方法

在默认操作描述符内引发的代码:

    internal static string VerifyActionMethodIsCallable(MethodInfo methodInfo) {
        // we can't call instance methods where the 'this' parameter is a type other than ControllerBase
        if (!methodInfo.IsStatic && !typeof(ControllerBase).IsAssignableFrom(methodInfo.ReflectedType)) {
            return String.Format(CultureInfo.CurrentUICulture, MvcResources.ReflectedActionDescriptor_CannotCallInstanceMethodOnNonControllerType,
                methodInfo, methodInfo.ReflectedType.FullName);
        }

        // we can't call methods with open generic type parameters
        if (methodInfo.ContainsGenericParameters) {
            return String.Format(CultureInfo.CurrentUICulture, MvcResources.ReflectedActionDescriptor_CannotCallOpenGenericMethods,
                methodInfo, methodInfo.ReflectedType.FullName);
        }

        // we can't call methods with ref/out parameters
        ParameterInfo[] parameterInfos = methodInfo.GetParameters();
        foreach (ParameterInfo parameterInfo in parameterInfos) {
            if (parameterInfo.IsOut || parameterInfo.ParameterType.IsByRef) {
                return String.Format(CultureInfo.CurrentUICulture, MvcResources.ReflectedActionDescriptor_CannotCallMethodsWithOutOrRefParameters,
                    methodInfo, methodInfo.ReflectedType.FullName, parameterInfo);
            }
        }

        // we can call this method
        return null;
    }

因为代码正在调用“methodinfo.containsGenericParameters”,我认为没有一种方法可以在不创建自己的actionDescriptor的情况下重写此行为。从源代码的角度来看,这似乎是不平凡的。

另一个选项是使控制器类成为通用类,并创建自定义通用控制器工厂。我有一些创建通用控制器的实验代码。虽然很简单,但这只是一个个人实验。

public class GenericControllerFactory : DefaultControllerFactory
{
    protected override Type GetControllerType(System.Web.Routing.RequestContext requestContext, string controllerName)
    {
        //the generic type parameter doesn't matter here
        if (controllerName.EndsWith("Co"))//assuming we don't have any other generic controllers here
            return typeof(GenericController<>);

        return base.GetControllerType(requestContext, controllerName);

        throw new InvalidOperationException("Generic Factory wasn't able to resolve the controller type");
    }

    protected override IController GetControllerInstance(System.Web.Routing.RequestContext requestContext, Type controllerType)
    {
        //are we asking for the generic controller?
        if (requestContext.RouteData.Values.ContainsKey("modelType"))
        {
            string typeName = requestContext.RouteData.Values["modelType"].ToString();
            //magic time
            return GetGenericControllerInstance(typeName, requestContext);
        }

        if (!typeof(IController).IsAssignableFrom(controllerType))
            throw new ArgumentException(string.Format("Type requested is not a controller: {0}",controllerType.Name),"controllerType");

        return base.GetControllerInstance(requestContext, controllerType);
    } 

    /// <summary>
    /// Returns the a generic IController tied to the typeName requested.  
    /// Since we only have a single generic controller the type is hardcoded for now
    /// </summary>
    /// <param name="typeName"></param>
    /// <returns></returns>
    private IController GetGenericControllerInstance(string typeName, RequestContext requestContext)
    {
        var actionName = requestContext.RouteData.Values["action"];

        //try and resolve a custom view model

        Type actionModelType = Type.GetType("Brainnom.Web.Models." + typeName + actionName + "ViewModel, Brainnom.Web", false, true) ?? 
            Type.GetType("Brainnom.Web.Models." + typeName + ",Brainnom.Web", false, true);

        Type controllerType = typeof(GenericController<>).MakeGenericType(actionModelType);

        var controllerBase = Activator.CreateInstance(controllerType, new object[0] {}) as IController;

        return controllerBase;
    }
}

六年后,当MVC5(和MVC6)在镇上时,我遇到了同样的问题。我正在用MVC5构建我的站点,这样我就可以安全地假设它还没有得到现成的支持。我登陆这里寻求解决办法。好吧,我最终找到了一种不侵入控制器或其工厂的方法来修复它,特别是因为我只在少数地方需要这个特性。

方法:稍微修改 Command Pattern (反正我已经在代码中使用过了)。

对于这个问题,首先定义接口

public interface IMyActionProcessor
{
    PartialViewResult Process<T>(T theModel);
}

以及相应的实施:

public sealed class MyActionProcessor : IMyActionProcessor
{
    // Your IoC container. I had it explicitly mapped just like any other 
    // registration to cause constructor injection. Using SimpleInjector, it will be 
    // <code>Container.Register(typeof(IServiceProvider), () => Container);</code>
    private IServiceProvider _serviceProvider;
    public MyActionProcessor(IServiceProvider serviceProvider) 
    {
        _serviceProvider = serviceProvider;
    }
    public PartialViewResult Process<T>(T theModel)
    {
        var handlerType =
            typeof(IMyActionHandler<>).MakeGenericType(theModel.GetType());

        dynamic handler = _serviceProvider.GetService(handlerType);

        return handler.Handle((dynamic)theModel);
    }
}

处理程序(上面代码中的userd)如下所示:

public interface IMyActionHandler<T> where T : class
{
    PartialViewResult Execute(T theModel);
}

有了以上这些,您现在所要做的就是根据类的具体情况为处理程序提供实现。 T . 像这样:

public class ModelClassHandler : IMyActionHandler<ModelClass>
{
    public PartialViewResult Execute(ModelClass theModel);
    {
        // Do Stuff here and return a PartialViewResult instance
    }
}

有了以上所有功能,您现在可以在控制器中简单地执行以下操作:

var processor = YourServiceLocator.GetService<IMyActionProcessor>();
var model = new ModelClass { /* Supply parameters */ };

var partialViewResult = processor.Process(model);

我知道这是一种额外的间接性,但效果很好。在我的例子中,我继续扩展处理程序和处理器,以便它们可以返回我想要的任何东西,而不仅仅是 PartialViewResult .

如果有一个更简单的解决方案的话,我会很感兴趣的。我想使用MVC时出现这种问题是不常见的。

PS:任何好的IOC容器都应该能够通过扫描程序集注册开放的泛型。因此,一旦正确配置,就不需要显式注册处理程序接口的实现。

PPS: This post provides better insight to the answer given here 特别是关于如何推广这个解。