If I do the following:

@page "/mypage"
@inject NavigationManager NavigationManager
<button @onclick="ts">nav to a random fragment</button>
@code{
  private void ts()
  {
     NavigationManager.NavigateTo($"/mypage#{Guid.NewGuid()}");
     StateHasChanged();
     Console.WriteLine(NavigationManager.Uri);
  }
}

I expect to see a different Guid in both the browser URL bar and in the console every time I click the button. I actually see that the browser URL changes properly but the URL written to the console never does.

Why is NavigationManager.Uri seemingly blatantly wrong? What can I do to get the current URL after I've changed its fragment?

I also tried modifying ts() to the following, which didn't help.

    private async Task ts()
    {
        NavigationManager.NavigateTo($"mypage#{Guid.NewGuid()}");
        StateHasChanged();
        await Task.Delay(1);
        Console.WriteLine(NavigationManager.Uri);
    }

On .NET 9; RenderMode is InteractiveWebAssembly.

If I do the following:

@page "/mypage"
@inject NavigationManager NavigationManager
<button @onclick="ts">nav to a random fragment</button>
@code{
  private void ts()
  {
     NavigationManager.NavigateTo($"/mypage#{Guid.NewGuid()}");
     StateHasChanged();
     Console.WriteLine(NavigationManager.Uri);
  }
}

I expect to see a different Guid in both the browser URL bar and in the console every time I click the button. I actually see that the browser URL changes properly but the URL written to the console never does.

Why is NavigationManager.Uri seemingly blatantly wrong? What can I do to get the current URL after I've changed its fragment?

I also tried modifying ts() to the following, which didn't help.

    private async Task ts()
    {
        NavigationManager.NavigateTo($"mypage#{Guid.NewGuid()}");
        StateHasChanged();
        await Task.Delay(1);
        Console.WriteLine(NavigationManager.Uri);
    }

On .NET 9; RenderMode is InteractiveWebAssembly.

• asp-core
• blazor

• I can't repro this exactly. I see the NavigationManager.Uri changing but 1 step behind. As always, specify Version(s) and RenderMode. – Henk Holterman Commented Apr 1 at 10:05
• Thanks, Henk. Did so. On .NET 9; RenderMode is InteractiveWebAssembly. – Patrick Szalapski Commented Apr 1 at 13:06

2 Answers 2

Fragment changes (#...) do not trigger a full navigation event in Blazor. Then NavigationManager.Uri does not reflect the new fragment until another navigation event happens. You could use JS interop to get to current URL.

@page "/mypage"
@inject IJSRuntime JSRuntime
@inject NavigationManager NavigationManager

<button @onclick="ts">nav to a random fragment</button>

@code {
    private async Task ts()
    {
        var newUrl = $"/mypage#{Guid.NewGuid()}";
        NavigationManager.NavigateTo(newUrl);
        var currentUrl = await JSRuntime.InvokeAsync<string>("eval", "window.location.href");
        Console.WriteLine(currentUrl);
    }
}

Your attempt with Task.Delay(1) was close. But things have changed, a 1ms delay isn't enough anymore. I think that Delay() got more 'accurate', not rounding up the value. Or something.

This will basically work:

    private async Task ts()
    {
        NavigationManager.NavigateTo($"mypage#{Guid.NewGuid()}");
        StateHasChanged();
        await Task.Delay(10);  // adapt to taste ...
        Console.WriteLine(NavigationManager.Uri);
    }

It's all because the NavigationManager is updated on (after) a Render. So the better, more reliable approach is to catch the value in OnAfterRender and build some change detecting logic there to use it.
You would then not need StateHasChanged() or Delay().