组件提交表单，服务端验证失败时还原页面并显示ModelState的错误信息

[SeriaWei]

How to use

Include @Html.HiddenForCurrentPagePath() to your form

<form method="post">
      @Html.HiddenForCurrentPagePath()
...
</form>

Use RenderRefererPageAttribute on your action

[HttpPost, RenderRefererPage]
public IActionResult Submit(MessageEntity entity)
{
    if (ModelState.IsValid)
    {
        ....
    }
    return View(entity);
}

Get model from widget service WidgetDisplayContext.Model:

public override WidgetViewModelPart Display(WidgetDisplayContext widgetDisplayContext)
{
    if (widgetDisplayContext.Model is MessageEntity messageEntity)
    {
        return widgetDisplayContext.ToWidgetViewModelPart(messageEntity);
    }

    return widgetDisplayContext.ToWidgetViewModelPart(new MessageEntity());
}