Question

如何使用ViewBag向页面传递非字符串的值

Answer 1

一：使用

ViewData使用：

[csharp] view plain copy print?
public ActionResult Index()
{
List<string> colors = new List<string>();
colors.Add("red");
colors.Add("green");
colors.Add("blue");
ViewData["listColors"] = colors;
ViewData["dateNow"]= DateTime.Now;
ViewData["name"] = "hejingyuan";
ViewData["age"]= 25;
return View();
}

View

[html] view plain copy print?
<p>
My name is <b>@ViewData["name"] </b>,<b>@ViewData["age"] </b>years old.
<br />
I like the following colors:
</p>
<ul id="colors">
@foreach (var color in ViewData["listColors"] as List<string>)
{
<li><font color="@color">@color </font></li>
}
</ul>
<p>
@ViewData["dateNow"]
</p>

ViewBag使用：

[csharp] view plain copy print?
public ActionResult Index()
{
List<string>colors = new List<string>();
colors.Add("red");
colors.Add("green");
colors.Add("blue");
ViewBag.ListColors = colors; //colors is List
ViewBag.DateNow= DateTime.Now;
ViewBag.Name= "hejingyuan";
ViewBag.Age = 25;
return View();
}

View

[html] view plain copy print?
<p>
My name is <b>@ViewBag.Name</b>, <b>@ViewBag.Age</b> years old.
<br />
I like the following colors:
</p>
<ul id="colors">
@foreach (var color in ViewBag.ListColors)
{
<li><font color="@color">@color</font> </li>
}
</ul>
<p>
@ViewBag.DateNow
</p>

在使用上，我们可以很明显的看出这两种方式的区别，只是存取值得方式有些区别而已！

二，定义

ViewBag定义

[csharp] view plain copy print?
public dynamic ViewBag {
get {
if (_dynamicViewData == null) {
_dynamicViewData = new DynamicViewDataDictionary(() => ViewData);
}
return _dynamicViewData;
}
}

ViewData定义
[csharp] view plain copy print?
public ViewDataDictionary ViewData {
get {
if (_viewData == null) {
SetViewData(new ViewDataDictionary());
}
return _viewData;
}
set {
SetViewData(value);
}
}

通过定义我们可以看出ViewBag 是ViewData的动态封装器，相当于在ViewData的基础上进行了封装处理。

三：对比

ViewData与ViewBag的区别

1、ViewData是字典类型，赋值方式用字典方式，通过key值读取对应的value，ViewData["myName"]
2、ViewBag是动态类型，使用时直接添加属性赋值即可ViewBag.myName
3、ViewBag和ViewData只在当前Action中有效，等同于View
4、ViewData和ViewBag中的值可以互相访问，因为ViewBag的实现中包含了ViewData