Remotely/Server/Components/FileInputButton.razor

@inject IJsInterop JsInterop

<InputFile id="@_hiddenInputId" type="file" style="display: none" multiple="@Multiple" OnChange="OnFileChanged" />

<button class="@ClassNames" @onclick="OpenFilePicker">
    @ButtonContent
</button>

@code {
    [Parameter]
    public string ClassNames { get; set; }

    [Parameter]
    public RenderFragment ButtonContent { get; set; }


    [Parameter]
    public Func<InputFileChangeEventArgs, Task> OnChanged { get; set; }

    [Parameter]
    public bool Multiple { get; set; }

    private readonly string _hiddenInputId = $"input-{Guid.NewGuid()}";


    private async Task OnFileChanged(InputFileChangeEventArgs args)
    {
        if (OnChanged is not null)
        {
            await OnChanged.Invoke(args);
        }
    }

    private void OpenFilePicker()
    {
        JsInterop.InvokeClick(_hiddenInputId);
    }
}