Extending model objects with ObjectProxy class
Recently I was looking for an easy way to extend my existing model objects with additional properties. The problem I had was that there was no option to mark these model classes as dynamic. What I came up with was a solution that uses the ObjectProxy class that comes with Flex. ObjectProxy essentially is a class that allows you to track property changes of its wrapped object. So what I also got with this approach was an ability to register a PropertyChangeEvent handler with my model objects.
The snippet below shows how I extend my User class object with an additional selected property. This is a view specific property so it wouldn’t really be a good practice to do it directly in the model.
// Wrapping each user into ObjectProxy with selected additional property selected var userProxy:ObjectProxy = new ObjectProxy({user:user, selected:false}); // Registering event PROPERTY_CHANGE handle userProxy.addEventListener(PropertyChangeEvent.PROPERTY_CHANGE, userProxy_propertyChangeHandler);
Below is a reason why I needed all that and how it works in practice; you can right-click the example to view the source code. BTW: If you are looking for a simple and quick way to have a dynamic Checkbox List this a way to go.
Another thing that the ObjectProxy class can resolve is a very common warning that occurs when you try to bind to not bindable properties: warning: unable to bind to property 'foo' on class 'Object' (class is not an IEventDispatcher).
I found this very useful too.
Paras Sheth
8 Nov 10 at 4:49 pm
Good example of using Object Proxy. If you are looking for simliar implementations, take a look at this blog post by Andrea. http://www.devahead.com/blog/2009/12/dynamic-objectproxy/
Dan
9 Nov 10 at 6:42 am
[...] Just highlighting some points: – Your view never can know your services you always have to link them into map file. – You dont need any code in your view (action script) because you can use the mediator to deal with all the callback functions as well as to populate your view. -I`m proxing the object user, for more information goto here [...]
Best Practices implementing services in mate | Arthur Neves
8 Dec 10 at 1:01 am
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Ernst Gomez
14 May 11 at 6:57 pm