默认情况下不支持此类行为，但您可以调整 AutoCompleteExtender 源以添加此功能。实际上有两种方法可用：第一种是扩展对象，从 Web 服务返回到扩展器，并为项目 css 类提供新属性，并在扩展器客户端脚本中应用此属性值。第二种可用的方法是为项目创建引入新事件，在页面上处理它并根据它的值在项目上应用自定义逻辑。让我们在这里实现这两种方法。首先，如果您还没有下载 AjaxControlToolkit 源代码并打开 Client/MicrosoftAjax.Extended/AutoComplete/AutoCompleteBehavior.pre.js 文件，则首先需要下载。在此文件中，您需要更改_update 方法，如下所示：
_update: function (prefixText, completionItems, cacheResults) {
/// <summary>
/// Method to update the status of the autocomplete behavior
/// </summary>
/// <param name="prefixText" type="String" DomElement="false" mayBeNull="true" />
/// <param name="completionItems" type="Object" DomElement="false" mayBeNull="true" />
/// <param name="cacheResults" type="Object" DomElement="false" mayBeNull="true" />
/// <returns />
if (cacheResults && this.get_enableCaching()) {
if (!this._cache) {
this._cache = {};
}
this._cache[prefixText] = completionItems;
}
// If the target control loses focus or
// if the value in textbox has changed before the webservice returned
// completion items we don't need to show popup
if ((!this._textBoxHasFocus) || (prefixText != this._currentCompletionWord())) {
this._hideCompletionList();
return;
}
if (completionItems && completionItems.length) {
this._completionListElement.innerHTML = '';
this._selectIndex = -1;
var _firstChild = null;
var text = null;
var value = null;
var cssClass = null;
var dataItem = null;
//remove this line if you don't need to implement itemDataBinding event
var itemDataBindingHandler = this.get_events().getHandler('itemDataBinding');
for (var i = 0; i < completionItems.length; i++) {
// Create the item
var itemElement = null;
if (this._completionListElementID) {
// the completion element has been created by the user and li won't necessarily work
itemElement = document.createElement('div');
} else {
itemElement = document.createElement('li');
}
// set the first child if it is null
if (_firstChild == null) {
_firstChild = itemElement;
}
// Get the text/value for the item
try {
dataItem = Sys.Serialization.JavaScriptSerializer.deserialize( completionItems[i] );
if (dataItem && dataItem.First) {
// Use the text and value pair returned from the web service
text = dataItem.First;
value = dataItem.Second;
if (dataItem.CssClass) {
cssClass = dataItem.CssClass;
}
}
else {
// If the web service only returned a regular string, use it for
// both the text and the value
text = completionItems[i];
value = text;
}
} catch (ex) {
text = completionItems[i];
value = completionItems[i];
}
// Set the text/value for the item
// ShowOnlyCurrentWordInCompletionListItem support
var optionText = this._showOnlyCurrentWordInCompletionListItem ? text : this._getTextWithInsertedWord(text);
itemElement.appendChild(document.createTextNode(optionText));
itemElement._value = value;
itemElement.__item = '';
if (this._completionListItemCssClass) {
Sys.UI.DomElement.addCssClass(itemElement, this._completionListItemCssClass);
} else {
var itemElementStyle = itemElement.style;
itemElementStyle.padding = '0px';
itemElementStyle.textAlign = 'left';
itemElementStyle.textOverflow = 'ellipsis';
// workaround for safari since normal colors do not
// show well there.
if (Sys.Browser.agent === Sys.Browser.Safari) {
itemElementStyle.backgroundColor = 'white';
itemElementStyle.color = 'black';
} else {
itemElementStyle.backgroundColor = this._textBackground;
itemElementStyle.color = this._textColor;
}
}
if (cssClass) {
Sys.UI.DomElement.addCssClass(itemElement, cssClass);
}
//remove this if you don't need to implement itemDataBinding event
if (itemDataBindingHandler) {
itemDataBindingHandler(itemElement, dataItem || completionItems[i]);
}
this._completionListElement.appendChild(itemElement);
}
var elementBounds = $common.getBounds(this.get_element());
this._completionListElement.style.width = Math.max(1, elementBounds.width - 2) + 'px';
this._completionListElement.scrollTop = 0;
this.raisePopulated(Sys.EventArgs.Empty);
var eventArgs = new Sys.CancelEventArgs();
this.raiseShowing(eventArgs);
if (!eventArgs.get_cancel()) {
this.showPopup();
// Check if the first Row is to be selected by default and if yes highlight it and updated selectIndex.
if (this._firstRowSelected && (_firstChild != null)) {
this._highlightItem(_firstChild);
this._selectIndex = 0;
}
}
} else {
this._hideCompletionList();
}
}
如果您不打算使用新的客户端事件来实现场景，这就是您需要的项目中的所有更改。您已经可以从 Web 服务器方法传递项目 css 类以及项目的文本和值。唯一的区别是使用自定义类而不是 AjaxControlToolkit 控件中默认使用的 Pair：
[WebMethod]
public string[] GetCompletionList(string prefixText, int count)
{
var serializer = new JavaScriptSerializer();
var items = Enumerable.Range(1, count)
.Select(id => serializer.Serialize(
new
{
Second = id,
First = prefixText + "_" + Guid.NewGuid().ToString(),
CssClass = id % 2 == 0 ? "even" : "odd"
}));
return items.ToArray();
}
如果您还想实现自定义客户端事件（确实提供了更大的灵活性），那么您需要向 AutoCompleteBehavior.pre.js 文件添加更多代码。在 Sys.Extended.UI.AutoCompleteBehavior.prototype 对象的下面某处添加代码：
add_itemDataBinding: function (handler) {
this.get_events().addHandler('itemDataBinding', handler);
},
remove_itemDataBinding: function (handler) {
this.get_events().removeHandler('itemDataBinding', handler);
},
另外，打开 Server/AjaxControlToolkit/AutoComplete/AutoCompleteExtender.cs 文件并将此属性添加到 AutoCompleteExtender 类：
/// <summary>
/// Handler to attach to the client-side item data binding event
/// </summary>
[DefaultValue("")]
[ExtenderControlEvent]
[ClientPropertyName("itemDataBinding")]
public string OnClientItemDataBinding
{
get { return GetPropertyValue("OnClientItemDataBinding", string.Empty); }
set { SetPropertyValue("OnClientItemDataBinding", value); }
}
重建项目后，您可以使用具有附加功能的自定义 AjaxControlToolkit 程序集。
<script type="text/javascript">
function itemDataBinding(item, dataItem) {
var value = parseInt(dataItem.Second, 10);
if (!isNaN(value)) {
item.className = value % 2 == 0 ? "even" : "odd";
}
}
</script>
<ajaxToolkit:AutoCompleteExtender runat="server" ID="autoComplete1"
TargetControlID="myTextBox" ServicePath="AutoComplete.asmx" ServiceMethod="GetCompletionList"
OnClientItemDataBinding="itemDataBinding">