gwms/GWMS.UI/Extensions/NavigationManagerExtension.cs

using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.WebUtilities;

namespace GWMS.UI.Extensions
{
    public static class NavigationManagerExtension
    {
        #region Public Methods

        public static T ExtractQueryStringByKey<T>(this NavigationManager navManager, string key)
        {
            var uri = navManager.ToAbsoluteUri(navManager.Uri);
            QueryHelpers.ParseQuery(uri.Query)
                .TryGetValue(key, out var queryValue);

            if (typeof(T).Equals(typeof(int)))
            {
                int.TryParse(queryValue, out int result);
                return (T)(object)result;
            }

            if (typeof(T).Equals(typeof(string)))
                return (T)(object)queryValue.ToString();

            return default;
        }

        #endregion Public Methods
    }
}