Question

我在那里有这段代码

   var anchor = new HtmlAnchor {HRef = temp, InnerText = this.LinkDescription};
            anchor.Attributes.Add("class", "navActive back");
            anchor.ServerClick += new EventHandler(AnchorServerClick);
            writer.Write("<div id=\"leftnav\"><ul><li>");
            anchor.RenderControl(writer);
            writer.Write("</li></ul></div>");

在自定义Web控件中。我在anchor.RenderControl上得到nullReference异常，为什么？我调试了上面的内容并且编写器不是null，也是锚点。那里发生了什么？谢谢！

编辑：我正在添加堆栈跟踪以进行调试

[NullReferenceException: Object reference not set to an instance of an object.]
System.Web.UI.HtmlControls.HtmlAnchor.GetPostBackOptions() +107
System.Web.UI.HtmlControls.HtmlAnchor.RenderAttributes(HtmlTextWriter writer) +10975634
System.Web.UI.HtmlControls.HtmlControl.RenderBeginTag(HtmlTextWriter writer) +56
System.Web.UI.HtmlControls.HtmlContainerControl.Render(HtmlTextWriter writer) +26
CER.Portal.Dashboard.Controls.BackLink.Render(HtmlTextWriter writer) +1151

Answer 1

查看GetPostBackOptions方法的代码，您需要将Page属性设置为当前页面，或将CausesValidation属性设置为false：

private PostBackOptions GetPostBackOptions()
{
   PostBackOptions options = new PostBackOptions(this, string.Empty) 
   {
      RequiresJavaScriptProtocol = true
   };
   if (this.CausesValidation && (this.Page.GetValidators(this.ValidationGroup).Count > 0))
   {
      options.PerformValidation = true;
      options.ValidationGroup = this.ValidationGroup;
   }
   return options;
}

在RenderControl调用之前添加 anchor.Page = this.Page 或 anchor.CausesValidation = false 。

HtmlAnchor.RenderControl抛出NullReference异常

1 个答案: