Contrôle de Dropdownlist avec <optgroup>s pour asp.net (webforms) ?

Question

Quelqu'un peut-il recommander un contrôle de liste déroulante pour asp.net (3.5) qui peut rendre des groupes d'options ? Merci

Answer 1

J'ai utilisé le contrôle standard dans le passé, et j'ai juste ajouté un simple ControlAdapter pour lui qui remplacerait le comportement par défaut afin qu'il puisse rendre les <optgroup>s à certains endroits. Cela fonctionne très bien même si vous avez des contrôles qui n'ont pas besoin du comportement spécial, car la fonctionnalité supplémentaire ne se met pas en travers du chemin.

Notez qu'il a été conçu dans un but spécifique et écrit en .Net 2.0. Il se peut donc qu'il ne vous convienne pas aussi bien, mais il devrait au moins vous donner un point de départ. En outre, vous devez le connecter à l'aide d'un fichier .browser dans votre projet (voir la fin de l'article pour un exemple).

'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
                    'TODO: make this stack-based, so the same option group can be used more than once in longer select element (check the most-recent stack item instead of anything in the list)
                    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

Voici une implémentation C# de la même classe :

/* 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();
    }
}

Le fichier de mon navigateur était nommé "App_Browsers". \BrowserFile.browser "et ressemblait à ceci :

<!--
    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>

Answer 2

J'ai utilisé JQuery pour réaliser cette tâche. J'ai d'abord ajouté un nouvel attribut pour chaque ListItem à partir de l'arrière-plan et ensuite utilisé cet attribut dans JQuery wrapAll() méthode pour créer des groupes...

C# :

foreach (ListItem item in ((DropDownList)sender).Items)
{
    if (System.Int32.Parse(item.Value) < 5)
        item.Attributes.Add("classification", "LessThanFive");
    else
        item.Attributes.Add("classification", "GreaterThanFive");
} 

JQuery :

$(document).ready(function() {
    //Create groups for dropdown list
    $("select.listsmall option[@classification='LessThanFive']")
        .wrapAll("<optgroup label='Less than five'>");
    $("select.listsmall option[@classification='GreaterThanFive']")
        .wrapAll("<optgroup label='Greater than five'>"); 
});

Answer 3

Merci Joel ! tout le monde... voici la version C# si vous la voulez :

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

//This codes makes the dropdownlist control recognize items with "--"'
//for the label or items with an OptionGroup attribute and render them'
//as  instead of .'
public class DropDownListAdapter : WebControlAdapter
{

    protected override void RenderContents(HtmlTextWriter writer)
    {
        DropDownList list = Control as DropDownList;
        string currentOptionGroup;
        List renderedOptionGroups = new List();

        foreach(ListItem item in list.Items)
        {
            if (item.Attributes["OptionGroup"] != null)
            {
                //'The item is part of an option group'
                currentOptionGroup = item.Attributes["OptionGroup"];
                //'the option header was already written, just render the list item'
                if(renderedOptionGroups.Contains(currentOptionGroup))
                    RenderListItem(item, writer);
                else
                {
                    //the header was not written- do that first'
                    if (renderedOptionGroups.Count > 0)
                        RenderOptionGroupEndTag(writer); //'need to close previous group'
                    RenderOptionGroupBeginTag(currentOptionGroup, writer);
                    renderedOptionGroups.Add(currentOptionGroup);
                    RenderListItem(item, writer);
                }
            }
            else if (item.Text == "--") //simple separator
            {
                RenderOptionGroupBeginTag("--", writer);
                RenderOptionGroupEndTag(writer);
            }
            else
            {
                //default behavior: render the list item as normal'
                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();
    }

}

Answer 4

Le code ci-dessus rend la balise de fin de l'optgroup avant les options, ce qui fait que les options ne sont pas indentées comme elles le devraient et que le balisage ne représente pas correctement le groupement. Voici ma version légèrement modifiée du code de Tom :

    public class ExtendedDropDownList : System.Web.UI.WebControls.DropDownList
{
    public const string OptionGroupTag = "optgroup";
    private const string OptionTag = "option";
    protected override void RenderContents(System.Web.UI.HtmlTextWriter writer)
    {
        ListItemCollection items = this.Items;
        int count = items.Count;
        string tag;
        string optgroupLabel;
        if (count > 0)
        {
            bool flag = false;
            string prevOptGroup = null;
            for (int i = 0; i < count; i++)
            {
                tag = OptionTag;
                optgroupLabel = null;
                ListItem item = items[i];
                if (item.Enabled)
                {
                    if (item.Attributes != null && item.Attributes.Count > 0 && item.Attributes[OptionGroupTag] != null)
                    {
                        optgroupLabel = item.Attributes[OptionGroupTag];

                        if (prevOptGroup != optgroupLabel)
                        {
                            if (prevOptGroup != null)
                            {
                                writer.WriteEndTag(OptionGroupTag);
                            }
                            writer.WriteBeginTag(OptionGroupTag);
                            if (!string.IsNullOrEmpty(optgroupLabel))
                            {
                                writer.WriteAttribute("label", optgroupLabel);
                            }
                            writer.Write('>');
                        }
                        item.Attributes.Remove(OptionGroupTag);
                        prevOptGroup = optgroupLabel;
                    }
                    else
                    {
                        if (prevOptGroup != null)
                        {
                            writer.WriteEndTag(OptionGroupTag);
                        }
                        prevOptGroup = null;
                    }

                    writer.WriteBeginTag(tag);
                    if (item.Selected)
                    {
                        if (flag)
                        {
                            this.VerifyMultiSelect();
                        }
                        flag = true;
                        writer.WriteAttribute("selected", "selected");
                    }
                    writer.WriteAttribute("value", item.Value, true);
                    if (item.Attributes != null && item.Attributes.Count > 0)
                    {
                        item.Attributes.Render(writer);
                    }
                    if (optgroupLabel != null)
                    {
                        item.Attributes.Add(OptionGroupTag, optgroupLabel);
                    }
                    if (this.Page != null)
                    {
                        this.Page.ClientScript.RegisterForEventValidation(this.UniqueID, item.Value);
                    }

                    writer.Write('>');
                    HttpUtility.HtmlEncode(item.Text, writer);
                    writer.WriteEndTag(tag);
                    writer.WriteLine();
                    if (i == count - 1)
                    {
                        if (prevOptGroup != null)
                        {
                            writer.WriteEndTag(OptionGroupTag);
                        }
                    }
                }
            }
        }
    }

    protected override object SaveViewState()
    {
        object[] state = new object[this.Items.Count + 1];
        object baseState = base.SaveViewState();
        state[0] = baseState;
        bool itemHasAttributes = false;

        for (int i = 0; i < this.Items.Count; i++)
        {
            if (this.Items[i].Attributes.Count > 0)
            {
                itemHasAttributes = true;
                object[] attributes = new object[this.Items[i].Attributes.Count * 2];
                int k = 0;

                foreach (string key in this.Items[i].Attributes.Keys)
                {
                    attributes[k] = key;
                    k++;
                    attributes[k] = this.Items[i].Attributes[key];
                    k++;
                }
                state[i + 1] = attributes;
            }
        }

        if (itemHasAttributes)
            return state;
        return baseState;
    }

    protected override void LoadViewState(object savedState)
    {
        if (savedState == null)
            return;

        if (!(savedState.GetType().GetElementType() == null) &&
            (savedState.GetType().GetElementType().Equals(typeof(object))))
        {
            object[] state = (object[])savedState;
            base.LoadViewState(state[0]);

            for (int i = 1; i < state.Length; i++)
            {
                if (state[i] != null)
                {
                    object[] attributes = (object[])state[i];
                    for (int k = 0; k < attributes.Length; k += 2)
                    {
                        this.Items[i - 1].Attributes.Add
                            (attributes[k].ToString(), attributes[k + 1].ToString());
                    }
                }
            }
        }
        else
        {
            base.LoadViewState(savedState);
        }
    }
}

Utilisez-le comme ça :

            ListItem item1 = new ListItem("option1");
        item1.Attributes.Add("optgroup", "CatA");
        ListItem item2 = new ListItem("option2");
        item2.Attributes.Add("optgroup", "CatA");
        ListItem item3 = new ListItem("option3");
        item3.Attributes.Add("optgroup", "CatB");
        ListItem item4 = new ListItem("option4");
        item4.Attributes.Add("optgroup", "CatB");
        ListItem item5 = new ListItem("NoOptGroup");

        ddlTest.Items.Add(item1);
        ddlTest.Items.Add(item2);
        ddlTest.Items.Add(item3);
        ddlTest.Items.Add(item4);
        ddlTest.Items.Add(item5);

et voici le balisage généré (en retrait pour faciliter la visualisation) :

 <select name="ddlTest" id="Select1">
    <optgroup label="CatA">
        <option selected="selected" value="option1">option1</option>
        <option value="option2">option2</option>
    </optgroup>
    <optgroup label="CatB">
        <option value="option3">option3</option>
        <option value="option4">option4</option>
    </optgroup>
    <option value="NoOptGroup">NoOptGroup</option>
 </select>

Answer 5

El Projet Sharp Pieces sur CodePlex résout ce problème (et plusieurs autres) de contrôle.