Kimseyi seçenek grupları işleyebilen ASP.NET (3.5) için bir dropdownlist kontrolü tavsiye edebilir misiniz? Teşekkürler

Geçmişte standart kontrol kullandım ve ekledi render <böylece, varsayılan davranışı geçersiz olacaktır; optgroup^ ControlAdapter bir basit . s bazı yerlerde. Bu ek özelliği karışmaz çünkü eğer özel bir davranışa gerek olmadığını denetler varsa bile harika çalışıyor.

Bu belirli bir amaç için ve yazılmış olduğunu unutmayın .2.0, çok Net de size uygun olmayabilir, ama en azından bir başlangıç noktası vermelidir. Ayrıca, bir kullanarak bağlayın .projenizde (bir örnek için yazının sonuna bakınız) browserfile.

'This codes makes the dropdownlist control recognize items with "--"
'for the label or items with an OptionGroup attribute and render them
'as <optgroup> instead of <option>.
Public Class DropDownListAdapter
    Inherits System.Web.UI.WebControls.Adapters.WebControlAdapter

    Protected Overrides Sub RenderContents(ByVal writer As HtmlTextWriter)
        Dim list As DropDownList = Me.Control
        Dim currentOptionGroup As String
        Dim renderedOptionGroups As New Generic.List(Of String)

        For Each item As ListItem In list.Items
                Page.ClientScript.RegisterForEventValidation(list.UniqueID, item.Value)
            If item.Attributes("OptionGroup") IsNot Nothing Then
                'The item is part of an option group
                currentOptionGroup = item.Attributes("OptionGroup")
                If Not renderedOptionGroups.Contains(currentOptionGroup) Then
                    'the header was not written- do that first
                    If (renderedOptionGroups.Count > 0) Then
                        RenderOptionGroupEndTag(writer) 'need to close previous group
                    End If
                    RenderOptionGroupBeginTag(currentOptionGroup, writer)
                    renderedOptionGroups.Add(currentOptionGroup)
                End If
                    RenderListItem(item, writer)
            ElseIf item.Text = "--" Then 'simple separator
                RenderOptionGroupBeginTag("--", writer)
                RenderOptionGroupEndTag(writer)
            Else
                'default behavior: render the list item as normal
                RenderListItem(item, writer)
            End If
        Next item

        If renderedOptionGroups.Count > 0 Then
            RenderOptionGroupEndTag(writer)
        End If
    End Sub

    Private Sub RenderOptionGroupBeginTag(ByVal name As String, ByVal writer As HtmlTextWriter)
        writer.WriteBeginTag("optgroup")
        writer.WriteAttribute("label", name)
        writer.Write(HtmlTextWriter.TagRightChar)
        writer.WriteLine()
    End Sub

    Private Sub RenderOptionGroupEndTag(ByVal writer As HtmlTextWriter)
        writer.WriteEndTag("optgroup")
        writer.WriteLine()
    End Sub

    Private Sub RenderListItem(ByVal item As ListItem, ByVal writer As HtmlTextWriter)
        writer.WriteBeginTag("option")
        writer.WriteAttribute("value", item.Value, True)
        If item.Selected Then
            writer.WriteAttribute("selected", "selected", False)
        End If

        For Each key As String In item.Attributes.Keys
            writer.WriteAttribute(key, item.Attributes(key))
        Next key

        writer.Write(HtmlTextWriter.TagRightChar)
        HttpUtility.HtmlEncode(item.Text, writer)
        writer.WriteEndTag("option")
        writer.WriteLine()
    End Sub
End Class

İşte C# aynı sınıftan uygulanması

/* This codes makes the dropdownlist control recognize items with "--"
 * for the label or items with an OptionGroup attribute and render them
 * as <optgroup> instead of <option>.
 */
public class DropDownListAdapter : WebControlAdapter
{
    protected override void RenderContents(HtmlTextWriter writer)
    {
        //System.Web.HttpContext.Current.Response.Write("here");
        var list = (DropDownList)this.Control;
        string currentOptionGroup;
        var renderedOptionGroups = new List<string>();

        foreach (ListItem item in list.Items)
        {
            Page.ClientScript.RegisterForEventValidation(list.UniqueID, item.Value);
            //Is the item part of an option group?
            if (item.Attributes["OptionGroup"] != null)
            {
                currentOptionGroup = item.Attributes["OptionGroup"];
                //Was the option header already written, then just render the list item
                if (renderedOptionGroups.Contains(currentOptionGroup))
                    RenderListItem(item, writer);
                //The header was not written,do that first
                else
                {
                    //Close previous group
                    if (renderedOptionGroups.Count > 0)
                        RenderOptionGroupEndTag(writer);

                    RenderOptionGroupBeginTag(currentOptionGroup, writer);
                    renderedOptionGroups.Add(currentOptionGroup);
                    RenderListItem(item, writer);
                }
            }
            //Simple separator
            else if (item.Text == "--")
            {
                RenderOptionGroupBeginTag("--", writer);
                RenderOptionGroupEndTag(writer);
            }
            //Default behavior, render the list item as normal
            else
                RenderListItem(item, writer);
        }

        if (renderedOptionGroups.Count > 0)
            RenderOptionGroupEndTag(writer);
    }

    private void RenderOptionGroupBeginTag(string name, HtmlTextWriter writer)
    {
        writer.WriteBeginTag("optgroup");
        writer.WriteAttribute("label", name);
        writer.Write(HtmlTextWriter.TagRightChar);
        writer.WriteLine();
    }
    private void RenderOptionGroupEndTag(HtmlTextWriter writer)
    {
        writer.WriteEndTag("optgroup");
        writer.WriteLine();
    }
    private void RenderListItem(ListItem item, HtmlTextWriter writer)
    {
        writer.WriteBeginTag("option");
        writer.WriteAttribute("value", item.Value, true);
        if (item.Selected)
            writer.WriteAttribute("selected", "selected", false);

        foreach (string key in item.Attributes.Keys)
            writer.WriteAttribute(key, item.Attributes[key]);

        writer.Write(HtmlTextWriter.TagRightChar);
        HttpUtility.HtmlEncode(item.Text, writer);
        writer.WriteEndTag("option");
        writer.WriteLine();
    }
}

Benim tarayıcı dosya "App_Browsers\BrowserFile seçildi.tarayıcı" ve bu gibi görünüyordu:

<!--
    You can find existing browser definitions at
    <windir>\Microsoft.NET\Framework\<ver>\CONFIG\Browsers
-->
<browsers>
   <browser refID="Default">
      <controlAdapters>
        <adapter controlType="System.Web.UI.WebControls.DropDownList" 
               adapterType="DropDownListAdapter" />
      </controlAdapters>
   </browser>
</browsers>