On 5/25/07, Justin Patrin <[EMAIL PROTECTED]> wrote:
> I'm just getting to the point in my flex application where I'm trying
> to implement binding between my model and view. I've set up
> bidirectional binding in the model and UI by setting a binding in
> each. The model uses normal object syntax to bind to the value of a UI
> element and the UI element uses E4X to bind to a node in the XML
> model.
>
> This works great when I'm using curly braces to define the bindings
> directly in the MXML. I get changes in the UI to propagate instantly
> to the model and changes in the model to propagate instantly to the
> UI. Great, I can now both save a load my data.
>
> The UI element looks like this:
> <mx:TextInput id="firstName" required="true"
> text="{model.personal_stuff.question.(@page_id ==
> 'personal_page_1').ApplicantFName}"/>
>
> The problem comes when I need to define my bindings in a different
> way. Currently many of my UI elements are defined in generic
> components which will be used in multiple applications with different
> models. I need to be able to set the bindings differently for
> different uses of the component. I though, no problem, I'll use a
> Binding tag.
>
> <mx:Binding source="model.personal_stuff.question.(@page_id ==
> 'personal_page_1').ApplicantFName.toString()"
> destination="firstName.text"/>
>
> This works fine if it's set up in the component that holds this
> element, but if I put it in an extended component, Flex fails with a
> runtime error about multiple child sets. Now, I can put this binding
> tag in the MXML where I'm including this component but I'd rather not
> so that I can make my code more modular and maintainable.
>
> The last option is to do this through ActionScript so I've tried to
> use BindingUtil to set up the binding. The obvious methods didn't work
> as E4X doesn't seem to be supported in the string syntax of the
> binding chain but it does seem to be possible to use the getter
> methods to get the value as well. The following will vause the correct
> value to be loaded into the UI element but only initially:
> public function getTT(personal_stuff : XMLList) : XML {
> var node : XML = personal_stuff[0].question.(@page_id ==
> 'personal_page_1')[0];
> return node;
> }
>
> public function getName(h : XML) : String {
> var n : XML = h.ApplicantFName[0];
> var s : String = n.toString();
> return s;
> }
> BindingUtils.bindProperty(firstName, "text", model, ["personal_stuff",
> {name: "question", getter: getTT}, {name: "ApplicantFName", getter:
> getName}]);
>
> However, further changes to the model's value don't cause the UI
> element to be updated.
>
> I'd love some help with this as the bindProperty's complex methods
> (through the chain and with the getter functions) don't have too many
> examples. For now I'm likely going to go with setting the Binding tags
> in my main Application where these pages are defined but I would like
> to know ow to make the AS version work as well, for future reference.
>
*Bump*, anyone else doing binding with E4X or XML structures?
--
Justin Patrin
