考试试卷实现思路与自定义控件的问题
大家好，请教一个关于自定义控件的问题，把问题描述清楚，篇幅比较长，请大家耐心查看。

正在做在线考试的功能，需求如下：
预览试卷：


图1

考试试卷：


图2

查看答卷：

图3

要做到以上的功能，我的思路是这样的：
1.问题（题目和选项）的显示，是最基本的，以上3个情况都包括了，因此把它们独立出来。
2.考试试卷，需要在选项旁边加入验证控件。查看答卷，需要在选项下面加入一段内容。总的来说，是在选项旁边加“东西”。

实现情况：
1.问题类型（预览试卷、考试试卷、查看答卷的问题），Question。题目（预览试卷、考试试卷、查看答卷的问题）类型，Subject。选项（预览试卷、考试试卷、查看答卷的选项）类型，Option。这3个概念，已经抽象并独立了。问题包含题目和选项。
2.需要加的内容，叫Decorator。
3.接着，是在考试试卷的选项旁边，加上验证控件。现在报错如下：


具体实现：
1.类图：


2.Question : CompositeControl

// 问题
internal abstract class Question : CompositeControl
    {


        internal Question(SubjectControl subjectControl, OptionControl optionControl)
        {
            this.subjectControl = subjectControl;
            this.optionControl = optionControl;
        }

        #region 构建容器界面

        protected override void CreateChildControls()
        {
            this.Controls.Clear();            

            // 问题内容
            this.phSubject = new PlaceHolder();
            this.phSubject.ID = "phSubject";
            this.phSubject.Controls.Add(this.CreateSubject(this._pqInfo.QuestionInfo.Content));
            this.Controls.Add(this.phSubject);

            // 选项
            this.phOption = new PlaceHolder();
            this.phOption.ID = "phOption";
            this.phOption.Controls.Add(this.optionControl);
            this.Controls.Add(phOption);
            
            this.ChildControlsCreated = true;
        }

        protected override void Render(HtmlTextWriter writer)
        {
            this.RenderSubject(writer);

            this.RenderOption(writer); 
 
        }


        protected virtual void RenderSubject(HtmlTextWriter writer)
        {
            #region 题目

            #region Tr

            writer.AddAttribute(HtmlTextWriterAttribute.Class, "tdbg");  // Begin Tr
            writer.RenderBeginTag(HtmlTextWriterTag.Tr);

            #region Td

            writer.AddAttribute(HtmlTextWriterAttribute.Class, "tdQuestion");   // Begin Td
            writer.AddAttribute(HtmlTextWriterAttribute.Colspan, "2");
            writer.RenderBeginTag(HtmlTextWriterTag.Td);

            hdnPaperQuestionID.RenderControl(writer);

            hdnCategoryID.RenderControl(writer);

            ltrID.RenderControl(writer);

            phSubject.RenderControl(writer);

            writer.RenderEndTag();  // End Td

            #endregion

            writer.RenderEndTag();  // End Tr

            #endregion

            #endregion
        }


        protected virtual void RenderOption(HtmlTextWriter writer)
        {
            #region 选项

            #region Tr

            writer.AddAttribute(HtmlTextWriterAttribute.Class, "tdbg");  // Begin Tr
            writer.RenderBeginTag(HtmlTextWriterTag.Tr);
            
            #region Td

            writer.AddAttribute(HtmlTextWriterAttribute.Class, "tdOption");   // Begin Td
            writer.AddAttribute(HtmlTextWriterAttribute.Colspan, "2");
            writer.RenderBeginTag(HtmlTextWriterTag.Td);

            phOption.RenderControl(writer);

            writer.RenderEndTag();  // End Td

            #endregion 
 

            writer.RenderEndTag();  // End Tr

            #endregion

            #endregion
        }

        #endregion

    }

3.ExamQuestion : Question

// 考试问题
internal class ExamQuestion : Question
    {

        internal ExamQuestion(SubjectControl subjectControl, OptionControl optionControl)
            : base(subjectControl, optionControl)
        {
        }

        protected override void CreateChildControls()
        {
            base.CreateChildControls();

            // 附加内容
            this.phDecorator = new PlaceHolder();
            this.phDecorator.ID = "phDecorator";

            OptionDecoratorContext odContext = new OptionDecoratorContext();
            OptionDecorator optionDecorator = odContext.GetOptionDecorator(this.PaperCategory, this.PqInfo.QuestionInfo.CategoryID);
            this.OptionDecorator = optionDecorator;
            optionDecorator.OptionControl = this.OptionControl;
            this.phDecorator.Controls.Add(optionDecorator);

            this.Controls.Add(phDecorator);
        }
        
        protected override void Render(HtmlTextWriter writer)
        {
            base.Render(writer);

            #region 附加功能

            writer.RenderBeginTag(HtmlTextWriterTag.Tr);

            writer.RenderBeginTag(HtmlTextWriterTag.Td);

            this.OptionDecorator.BeValidateControlClientID = this.OptionControl.Option.ClientID;

            this.OptionDecorator.RenderControl(writer);

            writer.RenderEndTag();

            writer.RenderEndTag();

            #endregion
        }

    } 
 

4.OptionControl

// 选项
internal abstract class OptionControl : CompositeControl
    {

        protected override void CreateChildControls()
        {
            this.Controls.Clear();

            this._option = this.CreateOptionControl(this._qInfo);
            this.Controls.Add(this._option);

            this.ChildControlsCreated = true;
        }

        protected override void Render(HtmlTextWriter writer)
        {
            this._option.RenderControl(writer);
        }

5.PaperSingleOption

// 单选选项
internal class PaperSingleOption : OptionControl
    {

        /// <summary>
        /// 构建考试题目的选项控件
        /// </summary>
        /// <param name="qInfo">题目试题</param>
        /// <returns>ASP.NET服务器控件</returns>
        internal override Control CreateOptionControl(QuestionInfo qInfo)
        {
            RadioButtonList _rblSingleChoice = new RadioButtonList();
            _rblSingleChoice.ID = "rblSingleChoice";
            _rblSingleChoice.Items.AddRange(this.ToListItem(qInfo.Option));
            _rblSingleChoice.RepeatDirection = RepeatDirection.Horizontal;

            return _rblSingleChoice;
        }

6.OptionDecorator

// 选项的附加功能
internal abstract class OptionDecorator : CompositeControl
    {


        protected override void CreateChildControls()
        {
            this.Controls.Clear();

            this._decorator = this.CreateOptionDecorator();
            this.Controls.Add(this._decorator);

            this.ChildControlsCreated = true;
        }

        

        protected override void Render(HtmlTextWriter writer)
        { 
 
            this._decorator.RenderControl(writer);
        }

7.RequiredValidator

[解决办法]
楼主，你进入调试模式，查看一下Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\目录下面生成的类文件再看看。