ASP.NET Core Razor Page - Paging

Index.cshtml

<h1>Index</h1>

<form method="get">
    <p>
        page @Model.PageNumber of @Model.TotalPages,
        showing @Math.Min(Model.PageSize, Model.Count) of @Model.Count rows
    </p>
    
    <button type="button" class="btn btn-dark"
            @Html.DisabledIf(Model.PageNumber <= 1)
            onclick="window.location.href = '@Model.PagedUrlWithFilter(Math.Max(1, Model.PageNumber - 1))'">
        &lt;&lt; Previous Page
    </button>
    <button type="button" class="btn btn-dark"
            @Html.DisabledIf(Model.PageNumber >= Model.TotalPages)
            onclick="window.location.href = '@Model.PagedUrlWithFilter(Math.Min(Model.TotalPages, Model.PageNumber + 1))'">
        Next Page &gt;&gt;
    </button>

    <pre> table from scaffold, then add search boxes per column </pre>
</form>

RazorIndexWithPaging.cs

namespace MyApp.Pages
{
    public partial class IndexModel : PageModel
    {
        [FromQuery(Name = "page")]
        public int PageNumber { get; set; } = 1;
    
        public string PagedUrlWithFilter(int page)
        {
            if (!this.Request.QueryString.HasValue)
            {
                if (page > 1)
                    return $"?page={page}";
                return "";
            }

            var pagedParams = new Dictionary<string, string>(this.Request.Query.Count, StringComparer.OrdinalIgnoreCase);
            var query = this.Request.Query;
            foreach (var p in query)
            {
                if (p.Value == Microsoft.Extensions.Primitives.StringValues.Empty || (p.Value.Count == 1 && p.Value[0].Length == 0))
                {
                    _logger.LogDebug($"empty {p.Key}, skipping");
                }
                else if (pagedParams.ContainsKey(p.Key))
                {
                    _logger.LogDebug($"{p} already present, skipping");
                }
                else if (p.Key == "page")
                {
                    _logger.LogDebug($"*page* found, skipping");
                }
                else
                {
                    _logger.LogDebug($"{p}");
                    pagedParams.Add(p.Key, p.Value.ToString());
                }
            }
            if (page > 1)
            {
                pagedParams.Add("page", page.ToString());
            }
            return QueryHelpers.AddQueryString("", pagedParams);
        }
        
        [BindProperty(SupportsGet = true)]
        public int PageSize { get; set; } = 100;

        public int Count { get; set; } = -1;

        public int TotalPages => Math.Max(1, (int)Math.Floor(this.Count / Math.Max(1.0, this.PageSize)));

        [BindProperty(SupportsGet = true)]
        public SearchModel Filter { get; set; } = new SearchModel();

        public async Task OnGetAsync([FromQuery] string sort) //, [FromQuery] string filter )
        {
            // TODO: implement Query()
            await Query(sort);
        }
    }
}