如何枚举MVC 5视图包

Question

Seems like viewbag is an instance of System.Web.Mvc.DynamicViewDataDictionary. Which is internal and so I cant cast ViewBag to it. And that type doesn't expose an IDictionary interface (cf ExpandoObject)

So how can I do this

foreach(var kv in <ViewBag magic>)
{
   .....
}

I see that System.Web.Mvc.DynamicViewDataDictionary has a Keys method but that doesn't help since I cannot get a dynamic object value dynamically. ie I cant do

var k = "Key1";
var v = ViewBag[k]; 

Answer 1

The ViewData property -- a ViewDataDictionary -- will contain the same data as ViewBag ( ViewBag is basically a wrapper around ViewData ).

A ViewDataDictionary is a structure that can be iterated (it implements IDictionary<string, object> and various IEnumerable s):

foreach (KeyValuePair<string, object> kvp in ViewData)
{

}

There are ways to cast ExpandoObject s to IDictionary<string, object> s but you're basically still in the same boat, since you will need to know what types you're working with to cast them from object to something useful.

Answer 2

The ViewBag acts as a wrapper on ViewData. You can use reflection to enumerate the properties of a ViewBag .

PropertyInfo pInfo = ViewBag.GetType().GetProperty("ViewData",
System.Reflection.BindingFlags.Public |
System.Reflection.BindingFlags.NonPublic |
System.Reflection.BindingFlags.Instance);

var viewDataDictionary = pInfo.GetValue(ViewBag, null);

The resulting dictionary will have a set of Keys and Values that can be enumerated.

Note: The ViewData property being reflected here is a Non Public member and you may want to decide between using a ViewBag and ViewData which directly permits enumeration.