middt_blazor-framework/Middt.Framework.Blazor.Web/Extensions/NavigationManagerExtension.cs
using Microsoft.AspNetCore.Components;
using System;
using System.Collections.Specialized;
using System.Web;

public static class NavigationManagerExtension
{
    public static NameValueCollection QueryString(this NavigationManager navigationManager)
    {
        return HttpUtility.ParseQueryString(new Uri(navigationManager.Uri).Query);
    }

    // get single querystring value with specified key
    public static string QueryString(this NavigationManager navigationManager, string key)
    {
        return navigationManager.QueryString()[key];
    }
}

