自定义控件子控件未持久保存到 ASP.NET 4.0 中的 ViewState

Question

我们刚刚将 ASP.NET Web 应用程序中的目标框架从 3.5 切换到 4.0。我们遇到了以下问题：

我们有几个自定义控件在 3.5 中运行良好，但现在在 4.0 中它们不再保留在 ViewState 中，其中一个基本上是继承 Label 类和 aspx 代码的其他控件的包装器看起来像这样：

<fsc:FormLabel ID="l_purchaserNo" runat="server" CssClass="label" Text="Purchaser">
    <asp:TextBox ID="tb_purchaserNo" runat="server" CssClass="textBox" MaxLength="50" />
</fsc:FormLabel>

生成的 html 是：

<span id="l_purchaserNo" class="label">
    <label class="header" for="tb_purchaserNo">Purchaser</label>
    <span class="valueContainer">
        <input name="tb_purchaserNo" type="text" id="tb_purchaserNo" class="textBox" />
    </span>
</span>

所以该控件基本上只是添加了一些 span 标签和一个连接到文本框的标签。

回发后，4.0 中的 html 代码是：

<span id="l_purchaserNo" class="label"></span>

即外部包装器中的所有内容都消失了，并且无法从后面的代码中检索文本框中输入的任何内容。

下面您可以找到 FormLabel 类的代码。

我们发现，通过在自定义控件 fsc:FormLabel 上设置 ViewStateMode=Disabled 并在 asp:TextBox 上设置 ViewStateMode=Enabled，内部控件会保留 ViewState，但同时我们会在包装器上丢失 ViewState，因为我们将文本翻译为包装标签，我们也需要 viewstate （实际上，我们尝试了每种组合，并且在 fsc:FormLabel 上设置 ViewStateMode=Enabled 没有帮助，无论我们如何在 页）。 EnableViewState 在所有级别上均为 true。

有人可以告诉我们如何让 ViewState 在 3.5 中像以前一样在所有控件（包装器以及包装控件）上工作吗？

谢谢克里斯蒂安

、泽利科、乔纳斯

using System;
using System.Collections.Generic;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace FormLabel
{
    public class FormLabel : Label
    {
        private bool HasChildren
        {
            get
            {
                return Controls.Count > 0;
            }
        }

        public override string Text
        {
            get
            {
                if (!HasChildren)
                {
                    return base.Text;
                }

                var text = ViewState[ID + "Text"] as String;

                if (text != null)
                {
                    ((LiteralControl)Controls[0]).Text = text;
                }

                return ((LiteralControl)Controls[0]).Text;
            }
            set
            {
                if (!HasChildren)
                {
                    base.Text = value;
                    return;
                }

                ((LiteralControl)Controls[0]).Text = value;
            }
        }

        public void SetText(string text)
        {
            ((LiteralControl)Controls[0]).Text = text;
            ViewState[ID + "Text"] = text;
        }


        public bool IndicateRequired
        {
            get
            {
                object state = ViewState[String.Format("{0}_IR", ID)];
                return state != null && (bool)state;
            }
            set
            {
                ViewState[String.Format("{0}_IR", ID)] = value;
            }
        }

        protected override void OnLoad(EventArgs e)
        {           
            ViewState[ID + "Text"] = Text;
            base.OnLoad(e);
        }

        protected override void Render(HtmlTextWriter writer)
        {
            if (HasChildren)
            {
                List<Control> controls = Controls.GetControls();
                List<BaseValidator> validators = Controls.GetValidators();

                WriteLabelControl(writer);
                WriteRequiredIndicator(writer);
                WriteControlHeader(writer, validators, this.GetFirstControl());
                WriteInnerControls(writer, controls);
                WriteLabelEndControl(writer);

                return;
            }

            base.Render(writer);
        }

        private void WriteLabelControl(HtmlTextWriter writer)
        {
            writer.WriteBeginTag("span");
            writer.WriteAttribute("id", ClientID);
            writer.WriteAttribute("class", CssClass);

            foreach (string attributeKey in Attributes.Keys)
            {
                writer.WriteAttribute(attributeKey, Attributes[attributeKey]);
            }

            writer.Write(HtmlTextWriter.TagRightChar);
        }

        private void WriteRequiredIndicator(HtmlTextWriter writer)
        {
            if (IndicateRequired)
            {
                writer.WriteBeginTag("span");
                writer.WriteAttribute("class", "requiredIndicator");
                writer.Write(HtmlTextWriter.TagRightChar);
                writer.WriteEndTag("span");
            }
        }

        private void WriteControlHeader(HtmlTextWriter writer, IEnumerable<BaseValidator> validators, Control userControl)
        {
            writer.WriteBeginTag("label");
            writer.WriteAttribute("class", "header");

            if (userControl != null)
            {
                writer.WriteAttribute("for", userControl.ClientID);
            }

            writer.Write(HtmlTextWriter.TagRightChar);
            writer.Write(Text);

            foreach (BaseValidator validator in validators)
            {
                validator.CssClass = "Error";
                validator.RenderControl(writer);
            }

            writer.WriteEndTag("label");
        }

        private static void WriteInnerControls(HtmlTextWriter writer, IList<Control> controls)
        {
            writer.WriteBeginTag("span");
            writer.WriteAttribute("class", "valueContainer");
            writer.Write(HtmlTextWriter.TagRightChar);

            for (int i = 1; i < controls.Count; i++)
            {
                controls[i].RenderControl(writer);
            }

            writer.WriteEndTag("span");
        }

        private static void WriteLabelEndControl(HtmlTextWriter writer)
        {
            writer.WriteEndTag("span");
        }

    }

    #region Nested type: Extensions

    public static class Extensions
    {
        public static List<BaseValidator> GetValidators(this ControlCollection controls)
        {
            var validators = new List<BaseValidator>();

            foreach (Control c in controls)
            {
                if (c is BaseValidator)
                {
                    validators.Add(c as BaseValidator);
                }

            }

            return validators;
        }

        public static List<Control> GetControls(this ControlCollection controls)
        {
            var listcontrols = new List<Control>();

            foreach (Control c in controls)
            {
                if (!(c is BaseValidator))
                {
                    listcontrols.Add(c as Control);
                }

            }

            return listcontrols;
        }

        public static Control GetFirstControl(this Control container)
        {
            return (new InputControlFinder().FindFirstInputControl(container));
        }

        private class InputControlFinder
        {
            public Control FindFirstInputControl(Control control)
            {
                Control input = null;

                foreach (Control child in control.Controls)
                {
                    if (child is TextBox || child is DropDownList || child is CheckBox)
                    {
                        input = child;
                    }
                    else
                    {
                        input = FindFirstInputControl(child);
                    }

                    if (input != null)
                    {
                        return input;
                    }
                }

                return input;
            }
        }
    }
    #endregion
}