By request, today I'm going to talk about user-based "hide whens" in Flex. Before we can do this we need to know as much as we can about the user.

Remember ages ago I talked about the "DEXT" object for JavaScript? Well, I've converted it in to a Flex-ready XML version, which you can see here.

By having Flex fetch this XML we know all we need to know about the user and whether to show them certain features. For example, here's the Simple app we're working on before the user has logged in:

Notice it says "Welcome Anonymous", there's a Login button and the "Create New Car" button is disabled. If you were to click the Login button and login (which you can try in the demo) you'd then see the screen re-adjust itself to look like this:

Notice that Anonymous has been replaced with the user's name, the Login button now says Logout and the new Car button has been disabled.

How Did It Do That?

The key to all this is binding. Let's look at the new Car button:

The enabled property of the button is tied (bound) to the last XML result of the httpSession object, which is used to fetch the user-defining XML from the server. Whenever the httpSession fetches the XML again the lastResult updates and so then does the enabled property of the button as they're bound together. There's no need to do anything other than trigger a request for the XML.

The same is true of the user name display and the label of the "login" button:

Sorry about the blurry images. You can see the code in full by right-clicking the demo.

So, do you get the notion of binding? Clever init!?

The only other note-worthy addition is the login dialog. Notice in the source code that there's now a new file called Login.mxml. This is a component. The idea being we can separate the login/out logic from out app and re-use it elsewhere. I've made a bit of a mess of it, but you get the idea.

Note that by creating components as separate files you can reference them in code by that filename as the name of the object. For example our code does this:

Notice we've created an instance of the Login component called loginWindow and then opened it using the PopupManager.

What Next?

I've been asked to talk about charts with Domino data so I think I'll cover that next. Then I'll probably talk about creating forms/document from Flex. If I get chance I'll re-factor all the code and then make it available for download again.