與<optgroup>下拉列表爲asp.net版本1.1？

Question

是否有可能創建一個包含optgroup s的選擇框和asp:DropDownList的asp.net版本1.1？

類似的問題已經在這裏和其他地方的要求與涉及ControlAdapters或類似的那些自定義控件從SharpPieces解決方案asp.net的新版本，但是這一切似乎並沒有與asp.net 1.1兼容

它會是手工製作html的唯一方法，還是有任何可用的控件可以爲這個舊的asp.net版本渲染帶有optgroup標籤的選擇框？

Answer 1

我之前做過一次，它在當時工作得很好。我將發佈相關的作品，以便您可以構建自己的作品（我的作品也只有一種只讀模式，但它可能不需要它）。

[DefaultProperty("Text"), 
     ValidationProperty("SelectedItem"), 
     ToolboxData("<{0}:EqualDropDownList runat=server></{0}:EqualDropDownList>"), 
     ToolboxBitmap(typeof(EqualDropDownList), "dropdown.BMP")] 
    public class EqualDropDownList:DropDownList 
    { 
/// The field in the datasource which provides values for groups 
     /// </summary> 
     [DefaultValue(""), Category("Data")] 
     public virtual string DataGroupField 
     { 
      get 
      { 
       object obj = this.ViewState["DataGroupField"]; 
       if (obj != null) 
       { 
        return (string) obj; 
       } 
       return string.Empty; 
      } 
      set 
      { 
       this.ViewState["DataGroupField"] = value; 
      } 
     } 


     /// <summary> 
     /// Render this control to the output parameter specified. 
     /// Based on the source code of the original DropDownList method 
     /// </summary> 
     /// <param name="writer"> The HTML writer to write out to </param> 
     protected override void RenderContents(HtmlTextWriter writer) 
     { 
      ListItemCollection items = this.Items; 
      int itemCount = this.Items.Count; 
      string curGroup = String.Empty; 
      string itemGroup; 
      bool bSelected = false; 

      if (itemCount <= 0) 
      { 
       return; 
      } 

      for (int i = 0; i < itemCount; i++) 
      { 
       ListItem item = items[i]; 
       itemGroup = item.Attributes["DataGroupField"]; 
       if (itemGroup != null && itemGroup != curGroup) 
       { 
        if (curGroup != String.Empty) 
        { 
         writer.WriteEndTag("optgroup"); 
         writer.WriteLine(); 
        } 

        curGroup = itemGroup; 
        writer.WriteBeginTag("optgroup"); 
        writer.WriteAttribute("label", curGroup, true); 
        writer.Write('>'); 
        writer.WriteLine(); 
       } 

       writer.WriteBeginTag("option"); 
       if (item.Selected) 
       { 
        if (bSelected) 
        { 
         throw new HttpException("Cant_Multiselect_In_DropDownList"); 
        } 
        bSelected = true; 
        writer.WriteAttribute("selected", "selected", false); 
       } 
       foreach (string key in item.Attributes.Keys) 
       { 
        writer.WriteAttribute(key, item.Attributes[key], false); 
       }     

       writer.WriteAttribute("value", item.Value, true); 
       writer.Write('>'); 
       HttpUtility.HtmlEncode(item.Text, writer); 
       writer.WriteEndTag("option"); 
       writer.WriteLine(); 
      } 
      if (curGroup != String.Empty) 
      { 
       writer.WriteEndTag("optgroup"); 
       writer.WriteLine(); 
      } 
     } 


     /// <summary> 
     /// Perform data binding logic that is associated with the control 
     /// </summary> 
     /// <param name="e">An EventArgs object that contains the event data</param> 
     protected override void OnDataBinding(EventArgs e) 
     { 
      // Call base method to bind data 
      base.OnDataBinding(e); 

      if (this.DataGroupField == String.Empty) 
      { 
       return; 
      } 

      // For each Item add the attribute "DataGroupField" with value from the datasource 
      IEnumerable dataSource = Util.GetResolvedDataSource(this.DataSource, this.DataMember); 
      if (dataSource != null) 
      { 
       ListItemCollection items = this.Items; 
       int i = 0; 

       string groupField = this.DataGroupField; 
       foreach (object obj in dataSource) 
       { 
        string groupFieldValue = DataBinder.GetPropertyValue(obj, groupField, null); 
        ListItem item = items[i]; 
        item.Attributes.Add("DataGroupField", groupFieldValue); 
        i++; 
       } 
      } 

     } 

} 

你需要這個類太：

public class Util 
    { 
     /// <summary> 
     /// This is copy of the internal ListControl method 
     /// </summary> 
     /// <param name="dataSource"></param> 
     /// <param name="dataMember"></param> 
     /// <returns></returns> 
     public static IEnumerable GetResolvedDataSource(object dataSource, string dataMember) 
     { 
      if (dataSource != null) 
      { 
       IListSource source1 = dataSource as IListSource; 
       if (source1 != null) 
       { 
        IList list1 = source1.GetList(); 
        if (!source1.ContainsListCollection) 
        { 
         return list1; 
        } 
        if ((list1 != null) && (list1 is ITypedList)) 
        { 
         ITypedList list2 = (ITypedList) list1; 
         PropertyDescriptorCollection collection1 = list2.GetItemProperties(new PropertyDescriptor[0]); 
         if ((collection1 == null) || (collection1.Count == 0)) 
         { 
          throw new HttpException("ListSource_Without_DataMembers"); 
         } 
         PropertyDescriptor descriptor1 = null; 
         if ((dataMember == null) || (dataMember.Length == 0)) 
         { 
          descriptor1 = collection1[0]; 
         } 
         else 
         { 
          descriptor1 = collection1.Find(dataMember, true); 
         } 
         if (descriptor1 != null) 
         { 
          object obj1 = list1[0]; 
          object obj2 = descriptor1.GetValue(obj1); 
          if ((obj2 != null) && (obj2 is IEnumerable)) 
          { 
           return (IEnumerable) obj2; 
          } 
         } 
         throw new HttpException("ListSource_Missing_DataMember"); 
        } 
       } 
       if (dataSource is IEnumerable) 
       { 
        return (IEnumerable) dataSource; 
       } 
      } 
      return null; 
     } 
    }