[轉]Html.DropDownList()的用法 ( Asp.Net MVC)

標籤：selected   啟用   intern   rabl   使用方法   讀取   屬性   list   model   

Html.DropDownList（）賦預設值：頁面代碼如下：  <%                 List<SelectListItem> list = new List<SelectListItem> {                new SelectListItem { Text = "啟用", Value = "0",Selected = true},                new SelectListItem { Text = "禁用", Value = "1" } };  %>//list儲存dropdownlist的預設值 <%=Html.DropDownList("state",list,Model.state) %>  //state為實體的屬性，預設選中"啟用"Html.DropDownList（）從資料庫讀取值：頁面代碼如下：<%= Html.DropDownList("Category", ViewData["Categories"] as SelectList,"--請選擇--",new { @class = "my-select-css-class" } )%>Controllers代碼：public ActionResult Create() {        List<Category> categories = categoryService.GetAll();        ViewData["Categories"] = new SelectList(categories, "Id", "Name");        return View();}  •原型一：public static string DropDownList(this HtmlHelper htmlHelper, string name){     IEnumerable<SelectListItem> selectData = htmlHelper.GetSelectData(name);     return htmlHelper.SelectInternal(null, name, selectData, true, false, null);}   第一種方式：List<SelectListItem> items = new List<SelectListItem>();items.Add(new SelectListItem() { Text = "001", Value = "1", Selected = false });items.Add(new SelectListItem() {Text = "002", Value = "2", Selected = false });ViewData["items"] = items; 簡化後：  var items = new List<SelectListItem>(){    (new SelectListItem() {Text = "001", Value = "1", Selected = false}),    (new SelectListItem() {Text = "002", Value = "2", Selected = false})};將items值給ViewData：ViewData["items"] = items; 在aspx中這樣使用：<%= Html.DropDownList("items") %> 產生的程式碼中，items將作為<select>標籤的name和id值。 •原型二：public static string DropDownList(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList){    return htmlHelper.DropDownList(name, selectList, null);}使用方法：<%= Html.DropDownList("items", new List<SelectListItem>{    (new SelectListItem() {Text = "001", Value = "1", Selected = false}),    (new SelectListItem() {Text = "002", Value = "2", Selected = false})})%>在這裡，不需要ViewData傳入值，第一個參數items作為標籤的name和id的值。items也可以是任意的字串。•原型三public static string DropDownList(this HtmlHelper htmlHelper, string name, string optionLabel){    IEnumerable<SelectListItem> selectData = htmlHelper.GetSelectData(name);    return htmlHelper.SelectInternal(optionLabel, name, selectData, true, false, null);}使用方法和第一種原型相同，string optionLabel作為一個預設的空的選項。這樣可以完成加入不需要選取任何選項的情境。 

 

[轉]Html.DropDownList()的用法 ( Asp.Net MVC)