Accessing Viewbag data in rendered Partial View

It uses the C# 4.0 dynamic feature. It achieves the same goal as viewdata and should be avoided in favor of using strongly typed view models (the same way as viewdata should be avoided).

So basically it replaces magic strings:

ViewData["Foo"]

with magic properties:

ViewBag.Foo

for which you have no compile time safety.

I continue to blame Microsoft for ever introducing this concept in MVC.

The name of the properties are case sensitive.

If you pass the ViewBag into the partial's viewdatadictionary, then pull it out (and cast), you can do whatever you want and the reference is kept. The cool part is that since it's dynamic, you can even add properties and then they'll show up on the parent page's Viewbag.

Page:

//set the viewbag into the partial's view data
@{Html.RenderPartial("Elaborate", Model, new ViewDataDictionary { {"vb", ViewBag}});}

Partial:

@{
   var vb = ((dynamic)ViewData["vb"]);
   vb.TheTitle = "New values";
 }

Page

@ViewBag.TheTitle = "New value"