在ASP.NET 5（vNext）MVC 6中添加自定义IRouter

Question

我正在尝试将此示例RouteBase实现转换为与MVC 6一起使用。我已经通过遵循路由项目中的示例来解决大部分问题，但我正在惹恼如何从方法返回异步Task 。 我真的不在乎它是否实际上是异步的（为任何可以提供答案的人欢呼），现在我只想让它运转起来。

我有传出路由功能（意味着当我输入路由值时ActionLink工作正常）。 问题在于RouteAsync方法。

public Task RouteAsync(RouteContext context)
{
    var requestPath = context.HttpContext.Request.Path.Value;

    if (!string.IsNullOrEmpty(requestPath) && requestPath[0] == '/')
    {
        // Trim the leading slash
        requestPath = requestPath.Substring(1);
    }

    // Get the page that matches.
    var page = GetPageList()
        .Where(x => x.VirtualPath.Equals(requestPath))
        .FirstOrDefault();

    // If we got back a null value set, that means the URI did not match
    if (page != null)
    {
        var routeData = new RouteData();

        // This doesn't work
        //var routeData = new RouteData(context.RouteData);

        // This doesn't work
        //routeData.Routers.Add(this);

        // This doesn't work
        //routeData.Routers.Add(new MvcRouteHandler());

        // TODO: You might want to use the page object (from the database) to
        // get both the controller and action, and possibly even an area.
        // Alternatively, you could create a route for each table and hard-code
        // this information.
        routeData.Values["controller"] = "CustomPage";
        routeData.Values["action"] = "Details";

        // This will be the primary key of the database row.
        // It might be an integer or a GUID.
        routeData.Values["id"] = page.Id;

        context.RouteData = routeData;

        // When there is a match, the code executes to here
        context.IsHandled = true; 

        // This test works
        //await context.HttpContext.Response.WriteAsync("Hello there");

        // This doesn't work
        //return Task.FromResult(routeData);

        // This doesn't work
        //return Task.FromResult(context);
    }

    // This satisfies the return statement, but 
    // I'm not sure it is the right thing to return.
    return Task.FromResult(0);
}

当匹配时，整个方法一直运行到最后。 但是当它完成执行时，它不会调用CustomPage控制器的Details方法。 我只是在浏览器中看到一个空白的白页。

我在这篇帖子中添加了WriteAsync行，它将Hello there写入空白页面，但是我无法理解为什么MVC没有调用我的控制器（在以前的版本中这没有顺利工作）。 不幸的是，该帖子涵盖了路由的每个部分，除了如何实现IRouter或INamedRouter 。

如何使RouteAsync方法起作用？

整个CustomRoute实现

using Microsoft.AspNet.Routing;
using Microsoft.Framework.Caching.Memory;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

public class PageInfo
{
    // VirtualPath should not have a leading slash
    // example: events/conventions/mycon
    public string VirtualPath { get; set; }
    public int Id { get; set; }
}

public interface ICustomRoute : IRouter
{ }


public class CustomRoute : ICustomRoute
{
    private readonly IMemoryCache cache;
    private object synclock = new object();

    public CustomRoute(IMemoryCache cache)
    {
        this.cache = cache;
    }

    public Task RouteAsync(RouteContext context)
    {
        var requestPath = context.HttpContext.Request.Path.Value;

        if (!string.IsNullOrEmpty(requestPath) && requestPath[0] == '/')
        {
            // Trim the leading slash
            requestPath = requestPath.Substring(1);
        }

        // Get the page that matches.
        var page = GetPageList()
            .Where(x => x.VirtualPath.Equals(requestPath))
            .FirstOrDefault();

        // If we got back a null value set, that means the URI did not match
        if (page != null)
        {
            var routeData = new RouteData();

            // TODO: You might want to use the page object (from the database) to
            // get both the controller and action, and possibly even an area.
            // Alternatively, you could create a route for each table and hard-code
            // this information.
            routeData.Values["controller"] = "CustomPage";
            routeData.Values["action"] = "Details";

            // This will be the primary key of the database row.
            // It might be an integer or a GUID.
            routeData.Values["id"] = page.Id;

            context.RouteData = routeData;
            context.IsHandled = true; 
        }

        return Task.FromResult(0);
    }

    public VirtualPathData GetVirtualPath(VirtualPathContext context)
    {
        VirtualPathData result = null;
        PageInfo page = null;

        // Get all of the pages from the cache.
        var pages = GetPageList();

        if (TryFindMatch(pages, context.Values, out page))
        {
            result = new VirtualPathData(this, page.VirtualPath);
            context.IsBound = true;
        }

        return result;
    }

    private bool TryFindMatch(IEnumerable<PageInfo> pages, IDictionary<string, object> values, out PageInfo page)
    {
        page = null;
        int id;
        object idObj;
        object controller;
        object action;

        if (!values.TryGetValue("id", out idObj))
        {
            return false;
        }

        id = Convert.ToInt32(idObj);
        values.TryGetValue("controller", out controller);
        values.TryGetValue("action", out action);

        // The logic here should be the inverse of the logic in 
        // GetRouteData(). So, we match the same controller, action, and id.
        // If we had additional route values there, we would take them all 
        // into consideration during this step.
        if (action.Equals("Details") && controller.Equals("CustomPage"))
        {
            page = pages
                .Where(x => x.Id.Equals(id))
                .FirstOrDefault();
            if (page != null)
            {
                return true;
            }
        }
        return false;
    }

    private IEnumerable<PageInfo> GetPageList()
    {
        string key = "__CustomPageList";
        IEnumerable<PageInfo> pages;

        // Only allow one thread to poplate the data
        if (!this.cache.TryGetValue(key, out pages))
        {
            lock (synclock)
            {
                if (!this.cache.TryGetValue(key, out pages))
                {
                    // TODO: Retrieve the list of PageInfo objects from the database here.
                    pages = new List<PageInfo>()
                    {
                        new PageInfo() { Id = 1, VirtualPath = "somecategory/somesubcategory/content1" },
                        new PageInfo() { Id = 2, VirtualPath = "somecategory/somesubcategory/content2" },
                        new PageInfo() { Id = 3, VirtualPath = "somecategory/somesubcategory/content3" }
                    };

                    this.cache.Set(key, pages,
                        new MemoryCacheEntryOptions()
                        {
                            Priority = CacheItemPriority.NeverRemove,
                            AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(15)
                        });
                }
            }
        }

        return pages;
    }
}

CustomRoute DI注册

services.AddTransient<ICustomRoute, CustomRoute>();

MVC路由配置

// Add MVC to the request pipeline.
app.UseMvc(routes =>
{
    routes.Routes.Add(routes.ServiceProvider.GetService<ICustomRoute>());

    routes.MapRoute(
        name: "default",
        template: "{controller=Home}/{action=Index}/{id?}");

    // Uncomment the following line to add a route for porting Web API 2 controllers.
    // routes.MapWebApiRoute("DefaultApi", "api/{controller}/{id?}");
});

如果重要，我使用的是Beta 5 ， DNX 4.5.1和DNX Core 5 。

解

我根据我在这里学到的信息创建了一个通用的解决方案，可以在这个答案中用于URL双向映射的简单主键。 在将其连接到MVC 6路由时，可以指定主键的控制器，操作，数据提供程序和数据类型。

Answer 1

正如@opiants所说，问题是你在RouteAsync方法中什么也没做。

如果您的目的是最终调用控制器操作方法，则可以使用以下方法而不是默认的MVC路由：

默认情况下，MVC使用带有内部目标IRouter的TemplateRoute 。 在RouteAsync中，TemplateRoute将委托给内部IRouter。 默认构建器扩展将此内部路由器设置为MvcRouteHandler 。 在您的情况下，首先添加一个IRouter作为您的内部目标：

public class CustomRoute : ICustomRoute
{
    private readonly IMemoryCache cache;
    private readonly IRouter target;
    private object synclock = new object();

    public CustomRoute(IMemoryCache cache, IRouter target)
    {
        this.cache = cache;
        this.target = target;
    }

然后更新您的启动以将该目标设置为MvcRouteHandler ，它已被设置为routes.DefaultHandler ：

app.UseMvc(routes =>
{
    routes.Routes.Add(
       new CustomRoute(routes.ServiceProvider.GetRequiredService<IMemoryCache>(), 
                       routes.DefaultHandler));

    routes.MapRoute(
        name: "default",
        template: "{controller=Home}/{action=Index}/{id?}");

    // Uncomment the following line to add a route for porting Web API 2 controllers.
    // routes.MapWebApiRoute("DefaultApi", "api/{controller}/{id?}");
});

最后，更新您的AsyncRoute方法以调用内部IRouter ，它将是MvcRouteHandler 。 您可以在TemplateRoute使用该方法的实现作为指导。 我很快就使用了这种方法并修改了你的方法如下：

public async Task RouteAsync(RouteContext context)
{
    var requestPath = context.HttpContext.Request.Path.Value;

    if (!string.IsNullOrEmpty(requestPath) && requestPath[0] == '/')
    {
        // Trim the leading slash
        requestPath = requestPath.Substring(1);
    }

    // Get the page that matches.
    var page = GetPageList()
        .Where(x => x.VirtualPath.Equals(requestPath))
        .FirstOrDefault();

    // If we got back a null value set, that means the URI did not match
    if (page == null)
    {
        return;
    }


    //Invoke MVC controller/action
    var oldRouteData = context.RouteData;
    var newRouteData = new RouteData(oldRouteData);
    newRouteData.Routers.Add(this.target);

    // TODO: You might want to use the page object (from the database) to
    // get both the controller and action, and possibly even an area.
    // Alternatively, you could create a route for each table and hard-code
    // this information.
    newRouteData.Values["controller"] = "CustomPage";
    newRouteData.Values["action"] = "Details";

    // This will be the primary key of the database row.
    // It might be an integer or a GUID.
    newRouteData.Values["id"] = page.Id;

    try
    {
        context.RouteData = newRouteData;
        await this.target.RouteAsync(context);
    }
    finally
    {
        // Restore the original values to prevent polluting the route data.
        if (!context.IsHandled)
        {
            context.RouteData = oldRouteData;
        }
    }
}

---

更新RC2

看起来在RC2 aspnet路由中不再出现TemplateRoute 。

我调查了历史，并在提交36180ab中将其重命名为RouteBase ，作为更大的重构的一部分。

Answer 2

这不起作用的主要原因是因为您没有在RouteAsync方法中执行任何RouteAsync 。 另一个原因是MVC 6中的路由工作方式与以前的MVC路由工作方式有很大不同，因此您可能最好使用源代码作为参考从头开始编写它，因为很少有文章可以解决MVC 6的问题。时刻。

编辑：@Daniel JG的答案比这更有意义，所以尽可能使用它。 这可能适合其他人的用例，所以我将其留在这里。

这里是一个非常简单的IRouter使用β7的实现。 这应该可行，但您可能需要填补空白。 您需要删除page != null并将其替换为下面的代码并替换控制器和操作：

if (page == null)
{
    // Move to next router
    return;
}

// TODO: Replace with correct controller
var controllerType = typeof(HomeController);
// TODO: Replace with correct action
var action = nameof(HomeController.Index);

// This is used to locate the razor view
// Remove the trailing "Controller" string
context.RouteData.Values["Controller"] = controllerType.Name.Substring(0, controllerType.Name.Length - 10);

var actionInvoker = context.HttpContext.RequestServices.GetRequiredService<IActionInvokerFactory>();

var descriptor = new ControllerActionDescriptor
{
    Name = action,
    MethodInfo = controllerType.GetTypeInfo().DeclaredMethods.Single(m => m.Name == action),
    ControllerTypeInfo = controllerType.GetTypeInfo(),
    // Setup filters
    FilterDescriptors = new List<FilterDescriptor>(),
    // Setup DI properties
    BoundProperties = new List<ParameterDescriptor>(0),
    // Setup action arguments
    Parameters = new List<ParameterDescriptor>(0),
    // Setup route constraints
    RouteConstraints = new List<RouteDataActionConstraint>(0),
    // This router will work fine without these props set
    //ControllerName = "Home",
    //DisplayName = "Home",
};

var accessor = context.HttpContext.RequestServices.GetRequiredService<IActionContextAccessor>();

accessor.ActionContext = new ActionContext(context.HttpContext, context.RouteData, descriptor);

var actionInvokerFactory = context.HttpContext.RequestServices.GetRequiredService<IActionInvokerFactory>();
var invoker = actionInvokerFactory.CreateInvoker(accessor.ActionContext);

// Render the page
await invoker.InvokeAsync();

// Don't execute the next IRouter
context.IsHandled = true;

return;

确保添加对Microsoft.Framework.DependencyInjection命名空间的引用以解析GetRequiredService扩展。

之后，按以下方式注册IRouter：

app.UseMvc(routes =>
{
    // Run before any default IRouter implementation
    // or use .Add to run after all the default IRouter implementations
    routes.Routes.Insert(0, routes.ServiceProvider.GetRequiredService<CustomRoute>());

    // .. more code here ...
});

然后在你的IOC注册，

services.AddSingleton<CustomRoute>();

另一种“更清洁”的方法可能是创建一个不同的IActionSelector实现。