HOW TO: Prevent Caching of web forms by the browser
Introduction
Well...this is not a topic of long article as such but a commonly asked
question.
"How can I prevent caching of my web form pages by the browser so that when
user clicks on the Back button of the browser he gets the latest output from the
server and not the cached one."
Solution
When you request a web form, ASP.NET processes it on the server and returns
it back to the browser. Browsers generally keep cache of web pages they visit to
improve performance and reduce network hits. That means when you navigate from
one page to another and use Back button of the browser, you are given copy of
the web form the browser cache and not from the server. Though this behavior is
fine for most of the case in some you need to prevent browser from such caching.
For example, you are developing a payment processing page where user enters
credit card number and other details. Once the form is submitted it should not
be cached on the client side. Pressing Back button should not display the old
details like credit card number.
To solve this problem here is a quick solution:
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetAllowResponseInBrowserHistory(false);
Add above two lines of code in the Page_Load event handler.
Here, we use two method of the Cache object.
- SetCacheability
- SetAllowResponseInBrowserHistory
The first method sets the Cache-Control HTTP header. This header controls how
documents are cached on the cache capable devices. The method accepts a
parameter of enumeration type - HttpCacheability. This enumeration has several
values such as - NoCache, Private, Public, Server, ServerAndNoCache and
ServerAndPrivate. The setting of NoCache means that the response will not be
cached on the client.
The second method SetAllowResponseInBrowserHistory indicates whether the
response will be kept in browser History. Passing the value of false means the
output will not be held in browser history.
Download
You can download a sample web application that illustrates how to use these
methods.
