29

我正在为后台工作人员创建一个 UrlHelper 以创建回调 url,这意味着它不是正常请求的一部分,我可以通过 DI 请求它。

在 ASP.Net 5 中,我可以只创建一个 HttpRequest 并为其提供与构建应用程序相同的 HttpConfiguration,但在 ASP.Net Core 2.0 中,UrlHelper 依赖于完整的 ActionContext,这有点难以制作。

我有一个可以工作的原型,但它使用了令人讨厌的 hack 将路由数据从应用程序启动过程中偷运出来。有一个更好的方法吗?

public class Capture
{
    public IRouter Router { get; set; }
}

public static class Ext
{
    // Step 1: Inject smuggler when building web host
    public static IWebHostBuilder SniffRouteData(this IWebHostBuilder builder)
    {
        return builder.ConfigureServices(svc => svc.AddSingleton<Capture>());
    }

    // Step 2: Swipe the route data in application startup
    public static IApplicationBuilder UseMvcAndSniffRoutes(this IApplicationBuilder app)
    {
        var capture = app.ApplicationServices.GetRequiredService<Capture>();
        IRouteBuilder capturedRoutes = null;
        app.UseMvc(routeBuilder => capturedRoutes = routeBuilder);
        capture.Router = capturedRoutes?.Build();
        return app;
    }

    // Step 3: Build the UrlHelper using the captured routes and webhost
    public static IUrlHelper GetStaticUrlHelper(this IWebHost host, string baseUri)
        => GetStaticUrlHelper(host, new Uri(baseUri));
    public static IUrlHelper GetStaticUrlHelper(this IWebHost host, Uri baseUri)
    {
        HttpContext httpContext = new DefaultHttpContext()
        {
            RequestServices = host.Services,
            Request =
                {
                    Scheme = baseUri.Scheme,
                    Host = HostString.FromUriComponent(baseUri),
                    PathBase = PathString.FromUriComponent(baseUri),
                },
        };

        var captured = host.Services.GetRequiredService<Capture>();
        var actionContext = new ActionContext
        {
            HttpContext = httpContext,
            RouteData = new RouteData { Routers = { captured.Router }},
            ActionDescriptor = new ActionDescriptor(),
        };
        return new UrlHelper(actionContext);
    }
}

// Based on dotnet new webapi

public class Program
{
    public static void Main(string[] args)
    {
        BuildWebHost(args);//.Run();
    }

    public static IWebHost BuildWebHost(string[] args)
    {
        var captured = new Capture();
        var webhost = WebHost.CreateDefaultBuilder(args)
            .SniffRouteData()
            .UseStartup<Startup>()
            .Build();

        var urlHelper = webhost.GetStaticUrlHelper("https://my.internal.service:48923/somepath");
        Console.WriteLine("YO! " + urlHelper.Link(nameof(ValuesController), null));
        return webhost;
    }
}

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, Capture capture)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseMvcAndSniffRoutes();
    }
}

[Route("api/[controller]", Name = nameof(ValuesController))]
public class ValuesController : Controller
{
    // GET api/values
    [HttpGet]
    public IEnumerable<string> Get()
    {
        return new string[] { "value1", "value2" };
    }

    // etc
}
4

2 回答 2

5

浏览资源似乎没有更少的hacky解决方案。

在 UseMvc() 方法中,正在构建的 IRouter 对象被传递给 RouterMiddleware,后者将其存储在私有字段中并仅将其公开给请求。因此,反射将是您唯一的其他选择,这显然已不再适用。

但是,如果您只需要使用 IUrlHelper.Content() 生成静态路径,则不需要路由器,因为默认实现不会使用它。在这种情况下,您可以像这样创建助手:

var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
var urlHelper = new UrlHelper(actionContext);
于 2018-01-29T21:27:14.957 回答
4

随着今天发布的 ASP.NET Core 2.2,他们添加了一个LinkGenerator类,听起来它可以解决这个问题(测试看起来很有希望)。我很想尝试一下,但由于我目前没有积极从事我需要这个的项目,所以它必须等待一段时间。但我很乐观,可以将此标记为新答案。

于 2018-12-04T18:55:14.563 回答