asp.net mvc - Browser back button and duplicate data entry -

i follow prg pattern avoid form resubmission problem when page refreshed. these action metods:

   public viewresult adddcoument(){       .....       return view();    }     [httppost]    public redirecttorouteresult savedocument(document doc){       //save document       return redirecttoaction("viewdocument",new { docid =doc.docid});    }     public viewresult viewdocument(string docid){       document doc=getdocumentbyid(docid);       return view(doc);    } 

when hit submit button document saved , redirected viewdocument action , helps prevent form resubmission when page refreshed. there's problem, problem can still click browser button, take me data entry form entered data remaining , can click submit again, means duplicate entry. 1 might need have unique entry not let duplicate saved server. in fact have , documentid, it's assigned automatically, not user input. how handle case?

update: actualy found way around issue. per this blog , many other threads need supply following http header in order turn off browser caching:

cache-control: no-cache, max-age=0, must-revalidate, no-store 

i've tried both following ways:

the encapsulated, oop way:

var cache=response.cache; cache.setexpires(datetime.utcnow.adddays(-1)); cache.setvaliduntilexpires(false); cache.setrevalidation(httpcacherevalidation.allcaches); cache.setcacheability(httpcacheability.nocache); cache.setnostore(); 

and appending header string:

response.appendheader("cache-control", "no-cache, max-age=0, must-revalidate, no-store"); 

i tried adding them both method renders form , post method submits form. still form inputs repopulated cache.