asp.net-mvc ViewData, ViewBag, TempData TempData life cycle
Example
Data saved to TempData is stored in the session and will be automatically removed at the end of the first request where the data is accessed. If never read, it will be kept until finally read or the session times out.
The typicaly usage looks like the following sequence (where each line is invoked from a different request):
//first request, save value to TempData
TempData["value"] = "someValueForNextRequest";
//second request, read value, which is marked for deletion
object value = TempData["value"];
//third request, value is not there as it was deleted at the end of the second request
TempData["value"] == null
This behavior can be further controller with the Peek and Keep methods.
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With
Peekyou can retrieve data stored in TempData without marking it for deletion, so data will still be available on a future request//first request, save value to TempData TempData["value"] = "someValueForNextRequest"; //second request, PEEK value so it is not deleted at the end of the request object value = TempData.Peek("value"); //third request, read value and mark it for deletion object value = TempData["value"]; -
With
Keepyou can specify that a key that was marked for deletion should actually be retained. In this case retrieving the data and saving it from deletion requires 2 method calls://first request, save value to TempData TempData["value"] = "someValueForNextRequest"; //second request, get value marking it from deletion object value = TempData["value"]; //later on decide to keep it TempData.Keep("value"); //third request, read value and mark it for deletion object value = TempData["value"];
With this in mind, use Peek when you always want to retain the value for another request and use Keep when retaining the value depends on additional logic.
