问ASP.net Core2如何向post请求添加额外数据？

EN

public class MyModel {
    public string Name { get; set; }
}

@using (Html.BeginForm("MyModelPost", "Home", FormMethod.Post))
{
    @Html.ValidationSummary(true)
    <fieldset>
        model field : @Html.TextBoxFor(model => model.Name) <br />
        custom field(can be any input) : <input type="hidden" name="extraParam" value="extra value" >
    </fieldset>
    <input type="submit" value="submit">
}

    [HttpPost]
    public IActionResult MyModelPost(MyModel model,string extraParam){
        Debug.WriteLine($"model param {model.Name}");
        Debug.WriteLine($"extra param {extraParam}");
        return View();
        //out put:
        // model param adsfs
        // extra param extra value

    }