o_19mgorv9t13a3ko71fev19l81mqa.pdf

TempData["Message"] = "Hello";
TempData["Date"] = DateTime.Now;
return RedirectToAction("Index");
}
...
When this method processes a request, it sets values in the TempData collection, and then redirects the user’s browser to
the Index action method in the same controller. You can read the TempData values back in the target action method,
and then pass them to the view, like this:
...
public ViewResult Index() {
ViewBag.Message = TempData["Message"];
ViewBag.Date = TempData["Date"];
return View();
}
...
A more direct approach would be to read these values in the view, like this:
@{
ViewBag.Title = "Index";
}
Index
The day is: @(((DateTime) TempData["Date"]).DayOfWeek)
The message is: @TempData["Message"]
Reading the values in the view means that you do not need to use the View Bag feature in the action method. However, you
must cast the TempData results to an appropriate type.
You can get a value from TempData without marking it for removal by using the Peek method, like this:
...
DateTime time = (DateTime)TempData.Peek("Date");
...
You can preserve a value that would otherwise be deleted by using the Keep method, like this:
...
TempData.Keep("Date");
...
The Keep method doesn’t protect a value forever. If the value is read again, it will be marked for removal once more. If
you want to store items so that they won’t be removed when the request is processed then use session data instead.
Returning Errors and HTTP Codes
The last of the built-in ActionResult classes that I will look at can be used to send specific error messages and HTTP
result codes to the client. Most applications do not require these features because the MVC Framework will automatically generate
these kinds of results. However, they can be useful if you need to take more direct control over the responses sent to the client.
Sending a Specific HTTP Result Code
You can send a specific HTTP status code to the browser using the HttpStatusCodeResult class. There is no
controller helper method for this, so you must instantiate the class directly, as shown in Listing 17-24.
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