XPages: Avoid saving duplicate documents on browser refresh

Update 22.06.10: Parameters are carried over when the redirect happens.
Update 02.09.10: Parameters starting with _ are stripped when redirect occurs

A reader wanted to know if there was some way to avoid duplicate documents when saving a document, refreshing the browser, and pressing ok on the resulting dialog. I wasn't able to recreate the problem of duplicate documents, but here's a workaround for the "POST" dialog. It should also take care of any duplicate documents on browser refresh.

In JSF lingo, this is known as the POST-Redirect-GET pattern. This is quite easy to accomplish in XPages.

On the save button, put the save action, and an Execute Script action. In the script part, call on the function below (put it in a SSJS Script Library/add it to the page). This makes the server redirect to the document in a get request, and you avoid the double posting problem.

function redirectToCurrentDocument( switchMode:boolean ){
  try {
    if( typeof currentDocument === 'undefined' || viewScope.stopRedirect ){ return; }
    // Gets the name of the XPage. E.g. /Person.xsp
    var page = view.getPageName();
    
    // Finds extra parameters, strips away XPages parameters/trims leading &
    var parameters = context.getUrl().getQueryString().substring(1);
    var extraParameters = parameters.replace( 
     /([&\?^]*_[a-z0-9=]+[&]{0,1})|(action=\w{4}Document[\&]{0,1})|(documentId=[\w]{32}[\&]{0,1})/ig, '').replace( /\&$/, '' );
    
    // Gets the unid of the current document
    var unid = currentDocument.getDocument().getUniversalID();
     
    // Sets/changes the action according according to the mode the document is in
    var isEditable = currentDocument.isEditable();
    if( switchMode ){ isEditable = !isEditable; } // false -> true / true -> false
    
    var action = ( isEditable ) ? 'editDocument' : 'openDocument';
     
    // Open the current document via a get request
    var redirectUrl = page + '?documentId=' + unid + '&action=' + action;
    if( extraParameters ){ redirectUrl += '&' + extraParameters; }
    context.redirectToPage( redirectUrl );
  } catch(e){ /* Exception logging */ }
}