MVC EditorFor Custom Helper

Question

我正在尝试为EditorFor创建一个自定义帮助器。我想从模型中获取字符串长度并将其添加到html属性。

到目前为止，我有以下内容，但这不适用于添加的新属性。

    public static IHtmlString MyEditorFor<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression, object ViewData, bool disabled = false, bool visible = true)
    {
        var member = expression.Body as MemberExpression;
        var stringLength = member.Member.GetCustomAttributes(typeof(StringLengthAttribute), false).FirstOrDefault() as StringLengthAttribute;

        RouteValueDictionary viewData =  HtmlHelper.AnonymousObjectToHtmlAttributes(ViewData);
        RouteValueDictionary htmlAttributes = HtmlHelper.AnonymousObjectToHtmlAttributes(viewData["htmlAttributes"]);

        if (stringLength != null)
        {
            htmlAttributes.Add("maxlength", stringLength.MaximumLength);
        }

        return htmlHelper.EditorFor(expression, ViewData);
    }

Answer 1

您将在方法参数中返回原始ViewData属性，而不是return htmlHelper.EditorFor(expression, ViewData)上的自定义HTML属性集合。基于this answer，您的返回方法应更改为：

public static IHtmlString MyEditorFor<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression, object ViewData, bool disabled = false, bool visible = true)
{
    var member = expression.Body as MemberExpression;
    var stringLength = member.Member.GetCustomAttributes(typeof(StringLengthAttribute), false).FirstOrDefault() as StringLengthAttribute;

    RouteValueDictionary viewData =  HtmlHelper.AnonymousObjectToHtmlAttributes(ViewData);
    RouteValueDictionary htmlAttributes = HtmlHelper.AnonymousObjectToHtmlAttributes(viewData["htmlAttributes"]);

    if (stringLength != null)
    {
        htmlAttributes.Add("maxlength", stringLength.MaximumLength);
    }

    return htmlHelper.EditorFor(expression, htmlAttributes); // use custom HTML attributes here
}

然后，在视图端应用自定义HTML帮助程序，如下所示：

@Html.MyEditorFor(model => model.Property, new { htmlAttributes = new { @maxlength = "10" }})

修改：

此方法适用于MVC 5（5.1）及更高版本，我不能确定它是否适用于早期版本（请参阅此问题：Html attributes for EditorFor() in ASP.NET MVC）。

对于早期的MVC版本，更优先使用HtmlHelper.TextBoxFor，当然具有maxlength属性：

return htmlHelper.TextBoxFor(expression, htmlAttributes);

其他参考资料：

Set the class attribute to Html.EditorFor in ASP.NET MVC Razor View

HTML.EditorFor adding class not working