Implementing PRG on JSF

I am currently investigating JSF in my current work. In the past, while using Spring and Struts, I always do a PRG (Post-Redirect-Get) whenever I do some开发者_如何学Pythonthing that could potentially update the model.

In JSF, I have read that the framework internally makes a forward request. So is it safe to assume that I should add redirect in those transaction that could potentially update the model?

My usecase for example. I have a JSP that display products in shopping cart, user can perform payment transaction. I dont want them to pay twice so I want to perform redirect

<navigation-rule>
   <from-view-id>/viewCart.jsp</from-view-id>
   <navigation-case>
      <from-outcome>pay</from-outcome>
      <to-view-id>/successPay.jsp</to-view-id>
      </redirect>
   </navigation-case>
</navigation-rule>

I worry about the user using their Back Button or hit Refresh on the browser?

Is my thinking correct or there is an alternative in JSF for these cases Thanks.

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Yes, adding <redirect/> is one of the right ways to make it a PRG.

Other ways involve manually calling ExternalContext#redirect() in bean action method, or (in JSF 2.x only) adding faces-redirect=true parameter to the (implicit navigation) outcome value, which can also be done by a custom configurable navigation handler.