ASP.Net Core 2.0:无需请求即可创建 UrlHelper [英] ASP.Net Core 2.0: Creating UrlHelper without request

问题描述

我正在为后台工作人员创建一个 UrlHelper 以创建回调 url，这意味着它不是我可以通过 DI 请求的普通请求的一部分.

I'm working on creating a UrlHelper for a background worker to create callback urls, which means it's not part of a normal request where I could just ask for it through DI.

在 ASP.Net 5 中，我可以创建一个 HttpRequest 并为其提供与我用来构建应用程序相同的 HttpConfiguration，但在 ASP.Net Core 2.0 中，UrlHelper 依赖于一个完整的 ActionContext，这有点难以制作.

In ASP.Net 5 I could just create a HttpRequest and give it the same HttpConfiguration I used to build my app, but in ASP.Net Core 2.0 the UrlHelper depends on a full ActionContext which is a bit harder to craft.

我有一个工作原型，但它正在使用令人讨厌的黑客将路由数据从应用程序启动过程中走私出来.有没有更好的方法来做到这一点?

I have a working prototype, but it's using a nasty hack to smuggle the route data out of the application startup process. Is there a better way to do this?

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
}

推荐答案

With ASP.NET Core 2.2 今天发布，他们添加了一个 LinkGenerator 类听起来可以解决这个问题(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参与我需要它的项目，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.

With ASP.NET Core 2.2 releasing today, they've added a LinkGenerator class that sounds like it will solve this problem (the tests look promising). I'm eager to try it, but as I'm not actively working on the project where I needed this at the moment, it will have to wait a bit. But I'm optimistic enough to mark this as a new answer.

这篇关于ASP.Net Core 2.0:无需请求即可创建 UrlHelper的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！