本文介绍了ASP.Net Core 2.0:无需请求即可创建UrlHelper的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
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
使用今天发布的ASP.NET Core 2.2 ，他们添加了 LinkGenerator 类听起来可以解决此问题(测试看起来很有希望).我很想尝试一下，但是由于我目前没有在需要此项目的项目上积极开展工作，因此它需要稍等片刻.但是我很乐观地将其标记为新答案.
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.
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.
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
}
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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