从FromLambdaExpression转换为CreateModelExpression并遇到问题

Question

我有以下代码段

    public static MvcHtmlString CIDropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string modelName)
    {
        TagBuilder containerDivBuilder = new TagBuilder("div");
        if (modelName == null) { throw new ArgumentNullException("modelName"); }
        ModelState modelState = helper.ViewData.ModelState[modelName];
        ModelErrorCollection modelErrors = (modelState == null) ? null : modelState.Errors;
        ModelError modelError = ((modelErrors == null) || (modelErrors.Count == 0)) ? null : modelErrors[0];

        var metadata = ModelMetadata.FromLambdaExpression(expression, helper.ViewData);

        if (metadata.IsRequired)
        {
         //Code goes here
        }

}

，我正在尝试升级到.net core 3.0，但在如何使用ModelExpression方面存在问题。我尝试了几种方法，但我明显遗漏了一些东西。无论如何，这是我的最新尝试。

    public static IHtmlContent CIDropDownListFor<TModel, TProperty>(this IHtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression, IEnumerable<Microsoft.AspNetCore.Mvc.Rendering.SelectListItem> selectList, string modelName)
    {

        if (modelName == null) { throw new ArgumentNullException("modelName"); }
        Microsoft.AspNetCore.Mvc.ModelBinding.ModelStateEntry modelState = helper.ViewData.ModelState[modelName];
        Microsoft.AspNetCore.Mvc.ModelBinding.ModelErrorCollection modelErrors = (modelState == null) ? null : modelState.Errors;
        Microsoft.AspNetCore.Mvc.ModelBinding.ModelError modelError = ((modelErrors == null) || (modelErrors.Count == 0)) ? null : modelErrors[0];

        IModelExpressionProvider meta;


        meta.CreateModelExpression(helper.ViewData, expression);
            if (meta.IsRequired)
        {
         //Code goes here
        }

一个示例代码将不胜感激。 预先感谢