On Sunday, June 5, 2011 2:31:13 PM UTC+2, Adam T wrote:
>
> Hi,
>
> I think you can do this relatively simply, but it's not directly noted
> in the documentation.
>
> (warning, a little plug ahead...) We're looking at how to do this for
> the 2nd edition of the GWT in Action book, and the approach below is
> where we are at the moment, though we have not thought through all
> implementations yet. The final solution will be described in detail
> in the book, but the following is the essence of the current solution:
>
> * GWT has a FilteredActivityMapper that you can use to run another
> activity rather than the one associated with the requested Place; for
> example if you go to a PhotoEditPlace when not logged in, you might
> want to run the LoginActivity rather than PhotoEditActivity.
>
This is basically what's causing the issue to all three of you. You'd rather
either treat authentication as an orthogonal concern to navigation (that
each activity then takes account of; possibly wrapping the "real" activity
in a "guard" activity if you want to also decouple authentication from your
activities: the "guard" activity would show a landing screen or whatever
until it receives a LoginEvent and then starts the wrapped "real" activity)
or treat it as a distinct place (similar to what you'd have with HTTP
redirects).
> * To do that, we created a Filter, such as:
>
> Filter filter = new Filter(){
> public Place filter(Place place) {
> // Always allow the WelcomePlace
> if(place instanceof WelcomePlace) return place;
>
> // If user is not logged in, redirect
> the activity for requested place to the login activity
> if(!isLoggedIn()) return loginPlace;
>
> // If user is logged in, then allow
> the requested place/activity
> else return place;
> }};
>
> * To use the filter, we created the ActivityMapper using a
> FilteredActivityMapper instead of the standard ActivityMapper, i.e.:
>
> // Difference to normal here
> ActivityMapper activityMapper = new
> FilteredActivityMapper(filter, new AppActivityMapper(clientFactory));
> // Carry on as normal from here
> ActivityManager activityManager = new
> ActivityManager(activityMapper, eventBus);
>
With the exception that you're splitting things into a
FilteredActivityMapper, you're basically doing the same as Stevko already
proposed.
> * In the login activity, there is code to refresh the browser page if
> the user logs in successfully (a simple Window.Location.reload() has
> worked so far)
>
If you can leave with a browser refresh, you'd better authenticate outside
your app: redirect to a login page that redirects back to the app, so that
when the app initializes you know whether the user is authenticated or not,
and you could even load a distinct GWT app: one for unauthenticated users, a
different one for authenticated ones.
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