问如何在GET-form提交后将查询参数映射到路由参数

EN

public class RewriteRules
{
    public static void RedirectRequests(RewriteContext context)
    {
        var request = context.HttpContext.Request;

        if (request.Query["SearchString"].ToString() != "")
        {
            var xx = $"{context.HttpContext.Request.Path.Value}/{request.Query["SearchString"].ToString()}";
            context.HttpContext.Response.Redirect ($"{context.HttpContext.Request.Path.Value}/{request.Query["SearchString"].ToString()}");
        }        
    }
}

app.UseRewriter(new RewriteOptions()
            .Add(RewriteRules.RedirectRequests)
            );

<form asp-controller="Home" asp-action="TestUrl" method="get">
<p>
    Title: <input type="text" name="SearchString">
    <input type="submit" value="Filter" />
</p>
</form>

[HttpGet("Home/TestUrl/{searchString?}")]
public async Task<IActionResult> TestUrl(string searchString)
    {
        return Json(searchString);
    }

config.Routes.MapHttpRoute("DefaultApiWithId", "Api/{controller}/{id}", new { id = RouteParameter.Optional }, new { id = @"\d+" });
config.Routes.MapHttpRoute("DefaultApiWithAction", "Api/{controller}/{action}");
config.Routes.MapHttpRoute("DefaultApiGet", "Api/{controller}", new { action = "Get" }, new { httpMethod = new HttpMethodConstraint(HttpMethod.Get) });
config.Routes.MapHttpRoute("DefaultApiPost", "Api/{controller}", new { action = "Post" }, new { httpMethod = new HttpMethodConstraint(HttpMethod.Post) });