MVC 4下拉默认值选择 [英] mvc 4 drop down default value selected

问题描述

我想在下拉列表中选择默认值，其中策略ID = 7，但它并没有选择的价值，我在做什么错了？

控制器：

  VAR PM =新ManagerClass（）;
IEnumerable的＆LT; MyClass的＆GT; PO = pm.GetDataFromDb（）;
IEnumerable的＆LT; SelectListItem＆GT;政策=新的SelectList（PO策略ID，Po​​licyName，新的{策略ID = 7}）;
ViewBag.Policies =政策;
 

查看：

  @ Html.DropDownListFor（M = GT; m.PolicyID，ViewBag.Policies为IEnumerable＆LT; SelectListItem＆gt;中新{@class =下拉场}）
 

解决方案

只需设置策略ID 属性在您的视图模型的价值，你想成为preselected

  VAR PM =新ManagerClass（）;
变种PO = pm.GetDataFromDb（）;
ViewBag.Policies =新的SelectList（PO策略ID，Po​​licyName）;viewModel.PolicyID = 7;
返回视图（视图模型）;
 

由于您的DropDownList被绑定到策略ID 属性（ M =＆GT; m.PolicyID ），那么它的决定哪些元素是preselected当值将被使用。

I want to select the default value in drop down list where policyId = 7 but it didn't select that value, what i am doing wrong?

Controller:

var pm = new ManagerClass();
IEnumerable<myClass> po = pm.GetDataFromDb();
IEnumerable<SelectListItem> Policies = new SelectList(po, "PolicyID", "PolicyName", new { PolicyID = 7 });
ViewBag.Policies = Policies;

View:

@Html.DropDownListFor(m => m.PolicyID, ViewBag.Policies as IEnumerable<SelectListItem>, new { @class = "dropdown-field"})

解决方案

Just set the PolicyID property on your view model to the value you want to be preselected:

var pm = new ManagerClass();
var po = pm.GetDataFromDb();
ViewBag.Policies = new SelectList(po, "PolicyID", "PolicyName");

viewModel.PolicyID = 7;
return View(viewModel);

Since your DropDownList is bound to the PolicyID property (m => m.PolicyID), then its value will be used when deciding which element to be preselected.

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