keep viewdata on RedirectToAction

问题

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult CreateUser([Bind(Exclude = "Id")] User user)
{
        ...
        db.SubmitChanges();
        ViewData["info"] = "The account has been created.";
        return RedirectToAction("Index", "Admin");
}

This doesnt keep the "info" text in the viewdata after the redirectToAction. How would I get around this issue in the most elegant way?

My current idea is to put the stuff from the Index controlleraction in a [NonAction] and call that method from both the Index action and in the CreateUser action, but I have a feeling there must be a better way.

Thanks.

回答1:

You can use TempData.

TempData["info"] = "The account has been created.".

TempData exists exactly for this situation. It uses Session as storage, but it will not be around after the second response.

From MSDN:

A typical use for a TempDataDictionary object is to pass data from an action method when it redirects to another action method. For example, an action method might store information about an error in the controller's TempData property (which returns a TempDataDictionary object) before it calls the RedirectToAction method. The next action method can then handle the error and render a view that displays an error message.

回答2:

Use ViewData if your data should be accessible in View during "this" request. Use `TempData' if your data is for "next" request (for example POST-REDIRECT-GET design pattern).

回答3:

If you need this more than once, a nice workaround would be creating ActionFilterAttributes which export/import the tempdata to viewdata and vice-versa. You can pass your ModelState in this way very nicely as well (demonstrated here - #13). With a few adjustments to that piece of code you would have a clean solution, I think.

回答4:

You could use the TempData controller property, but it has the disadvantage that it uses the session storage in the background. This means that you'll have extra work getting it to function on a web farm and you'll need to have sessions enabled in your application in the first place.

An alternative is to use cookies if you only need to transport a short message. This does require proper encryption of the cookie. Not relying on the TempData property also allows you to set messages in a non MVC context, for example in a classic ASHX page.

Take a look at FlashMessage which can save you some work implementing this yourself.

回答5:

Since TempData appears to use storage, and any form of ITempDataProvider that is not "in-process", requires the object to be Serializable, TempData seems woefully inadequate in web farm situations... (ViewDataDictionary isn't itself serializable...) Does anyone have any suggestions for this?

来源：https://stackoverflow.com/questions/1226329/keep-viewdata-on-redirecttoaction