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Confusing MVC Interview questions on TempData , Peek and Keep

By Shiv Prasad Koirala in ASP.NET
Sep 15th, 2014
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Introduction

One of the most asked MVC interview question is around tempdata , viewdata and viewbag. Further we have seen lot of MVC interviewers confuse developers with TempData , Peek and Keep questions. This section will clarify the confusion around the same.

What is need of "TempData" ?

TempData helps to preserve data throughout the current request. The request can travel through action to action or controller to controller until the view is displayed.

What is difference between TempData and ViewData ?

"TempData" maintains data for the complete request while "ViewData" maintains data only from Controller to the view.

Does "TempData" preserve data in the next request also?

"TempData" is available through out for the current request and in the subsequent request it's available depending on whether "TempData" is read or not.

So if "TempData" is once read it will not be available in the subsequent request.

What is the use of Keep and Peek in "TempData"?

Once "TempData" is read in the current request it's not available in the subsequent request. If we want "TempData" to be read and also available in the subsequent request then after reading we need to call "Keep" method as shown in the code below.

@TempData["MyData"];

TempData.Keep("MyData");

The more shortcut way of achieving the same is by using "Peek". This function helps to read as well advices MVC to maintain "TempData" for the subsequent request.

string str = TempData.Peek("Td").ToString();

If you want to read more in detail you can read from this detailed blog on MVC Peek and Keep.

If you want to Learn MVC from start below is the video link for the same.