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，这意味着它不是正常请求的一部分，而我只能通过DI来请求它.

在ASP.Net 5中，我可以创建一个HttpRequest并为其提供与构建我的应用程序时相同的HttpConfiguration，但是在ASP.Net Core 2.0中，UrlHelper依赖于完整的ActionContext，这很难编写./p>

我有一个可以正常工作的原型，但是它正在使用一个讨厌的黑客将路由数据走私到应用程序启动过程之外.有更好的方法吗?

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
}

解决方案

使用 LinkGenerator 类听起来可以解决此问题(

解决方案

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.

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