Reloading Page is giving rise to post data one more time (.NET issue)

I am trying to create something like shopping chart. The user adds products to his/her cart but if it click refresh button on the browser, the last product ,that is added before, is added one more time. How can I solve this problem ?

Thanks i开发者_如何转开发n advance,

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You're looking for the POST-Redirect-GET pattern.