mapo-core/MP.Stats/Components/DataPager.razor

<div class="input-group input-group-sm">
    row/pag:&nbsp;
    <select @bind="@numRecord" class="form-control form-control-sm">
        <option value="5">5</option>
        <option value="10">10</option>
        <option value="25">25</option>
        <option value="50">50</option>
        <option value="100">100</option>
    </select>
</div>

@code {

    protected int _numRecord { get; set; } = 10;

    [Parameter]
    public int numRecord
    {
        get
        {
            return _numRecord;
        }
        set
        {
            bool doReport = !_numRecord.Equals(value);
            _numRecord = value;
            if (doReport)
            {
                reportChange();
            }
        }
    }

    [Parameter]
    public EventCallback<int> numRecordChanged { get; set; }

    private void reportChange()
    {
        numRecordChanged.InvokeAsync(numRecord);
    }

}