Nothing happened with custom IRouter in Asp.Net Co

问题:

I have the following implementation of my router:

public class TenantUrlResolverRouter : IRouter
{
    private readonly IRouter _defaultRouter;

    public TenantUrlResolverRouter(IRouter defaultRouter)
    {
        _defaultRouter = defaultRouter;
    }

    public VirtualPathData GetVirtualPath(VirtualPathContext context)
    {
        return _defaultRouter.GetVirtualPath(context);
    }

    public async Task RouteAsync(RouteContext context)
    {
        var oldRouteData = context.RouteData;
        var newRouteData = new RouteData(oldRouteData);
        newRouteData.Values["library"] = "Default";
        try
        {
            context.RouteData = newRouteData;
            await _defaultRouter.RouteAsync(context);
        }
        finally
        {
            if (!context.IsHandled)
            {
                context.RouteData = oldRouteData;
            }
        }
    }
}

Then I define it in Startup.cs:

app.UseMvc(routes =>
        {
            routes.Routes.Add(
                new TenantUrlResolverRouter(routes.DefaultHandler));
            routes.MapRoute(
                name: "default",
                template: "{library=Unknown}/{controller=Home}/{action=Index}/{id?}");
        });

But nothing happens, RouteData.Values in RouteContext always empty, I always have Unknown, while it's need to be Default. That's not the problem of the predefined template, because it even worked without the {library=Unknown} and this {library}/{controller=Home}/{action=Index}/{id?} doesn't work too.

What's the problem with this custom IRouter?

回答1:

You are not providing a complete set of route values. In order to route to an action, you need to provide both controller and action.

Also, you don't have a match condition in the route. A match condition will determine whether the incoming request matches the current route. In the built-in routing, the url and constraints are match conditions. However, in a custom route, you need to put an if block to ensure that any request that doesn't match will pass through to the next registered route.

NOTE: This is the most powerful part of custom routing. The built-in routing can only match against URLs. But with custom routing, you can match anything in the request. For example, you could make the route match only for a certain domain or a certain subdomain. You could even make it match things like posted form values or session state.

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);
    }

    var segments = requestPath.Split('/');

    // Required: Match condition to determine if the incoming request
    // matches this route. If not, you should allow the framework to
    // match another route by doing nothing here.
    if (segments.Length > 0 && segments[0].Equals("libraryname", StringComparison.OrdinalIgnoreCase))
    {
        var oldRouteData = context.RouteData;
        var newRouteData = new RouteData(oldRouteData);
        newRouteData.Values["library"] = segments[0];
        newRouteData.Values["controller"] = segments[1];
        newRouteData.Values["action"] = segments[2];
        try
        {
            context.RouteData = newRouteData;
            await _defaultRouter.RouteAsync(context);
        }
        finally
        {
            if (!context.IsHandled)
            {
                context.RouteData = oldRouteData;
            }
        }
    }
}

See this question for more info about implementing IRouter.