Equivalent of Flex DataBinding using Pure Actionscript - apache-flex

When Flex Sees Something Like This:
<mx:Label text="Hello {MyVar} World!"/>
It Must Translate That Somehow Into ActionScript. But What If I Need To Do Something Similar, At Runtime. How Can I Accomplish What DYNAMICALLY? WHEN I DO NOT KNOW THE CONTENTS OF THE BINDING TEMPLATE.
In ActionScript it would need it to look something like this:
public function CustomDynamicBinding(StringToBind:String):Label {
// *EXAMPLES* Of StringToBind:
// "Hello {MyVar} World!"
// "Product: {name} ${price}.00"
// "{data.label}, {data.description}"
// I've Written It This Way Because I DO NOT KNOW The Exact Text To Be Bound At Design Time.
[Bindable]
var Lab:Label=new Label();
Lab.text=???
return(Lab);
}
How can I accomplish this kind of "Dynamic" binding... Where I don't know the value of "StringToBind" until runtime? For the purposes of this question we can assume that I do know that any variable(s) mentioned in "StringToBind", are guaranteed to exist at runtime.
I already realize there are much more straightforward ways to accomplish this exact thing STATICALLY, and using only Flex/MXML. It's important for my project though that I understand how this could be accomplished without MXML.
Doing This:
lab.text = stringToBind.replace("{myVar}", str);
Will NOT work because this simply assigns ONCE the value of "{myVar}" - (which may not even BE the variable referenced in "stringToBind"!!) to the label, and does not take into account when and if myVar changes! Wouldn't I need to somehow use something Like bindProperty?

Use BindingUtils.bindSetter
var stringToBind:String = "Hello {myVar} World!";
[Bindable]
var myVar:String = 'Flex';
var lab:Label = new Label();
BindingUtils.bindSetter(labelValue, this, "myVar");
function set labelValue(str:String):void
{
lab.text = "Hello " + str + " World!";
//or if you want it dynamic
lab.text = stringToBind.replace("{myVar}", str);
}
Note that this is not pure ActionScript in its strict sense as data binding itself is a Flex concept; this is just MXML-less syntax of doing it. You're still using Flex binding internally - but again, use of Label alone makes if Flexy

private function _BindingSource_bindingsSetup():Array
{
var result:Array = [];
result[0] = new mx.binding.Binding(this,
function():String
{
var result:* = "Hello " + (MyVar) + " World!";
return (result == undefined ? null : String(result));
},
null,
"_BindingSource_Label1.text"
);
return result;
}
It's only a part of generated code. Feel free to add -keep-generated-actionscript parameter to compiler options and read all generated ActionScript in bin-debug\generated.

Disclosure: shameless self promotion
The BindageTools library provides an intuitive builder API for setting up bindings in ActionScript.

Related

Select option value - selectedchoice is not working

I am binding a SELECT HTML tag with some dynamic values using knockout JS. Additionally, i am trying to set a selected choice which is failing. Please suggest where i am going wrong.
self.level1Choices.selectedChoice = ko.observable(2); - this line does not seem to work.
The JSFiddle for this code is at http://jsfiddle.net/oarp7gwj/7/
The dropdown is not loading in the JSFiddle for some reason. I dont think i have referenced the knockout JS correctly. In my local environment, I am able to load the select box with the values. However, i am not able to set the selected value.
#Wayne Ellery, #QBM5 - please advise since you know about this already :)
You should use var to declare your model object to avoid scoping issues
var viewModel = new DataModel();
The main issue was you need to add to the Datamodel by exposing it through the this variable in the Datamodel.
var DataModel = function (client) {
var self = this;
self.level1Choices = ko.observableArray();
};
Take a look at the Helo World example as to how to do this:
http://knockoutjs.com/examples/helloWorld.html
I've scoped this to self as it's a best practice to not worry about this referring to something else mentioned here: http://knockoutjs.com/documentation/computedObservables.html.
I moved the loadAllApprovers method inside the DataModel as this is where it belongs and so that it has access to populate the datamodel.
I added the mobile services client to the constructor so that it can be mocked for testing your model.
var DataModel = function (client) {
var self = this;
self.level1Choices = ko.observableArray();
var loadAllApprovers = function () {
var allAppprovers = client.getTable('TABLE');
var query = allAppprovers.select("ID", "FirstName").read().done(function (approverResults) {
self.level1Choices(approverResults);
}, function (err) {
console.log("Error: " + err);
});
};
loadAllApprovers();
};
You were also missing knockout in your jsfiddle.
http://jsfiddle.net/az4rox0q/6/

embedding sources dynamically

is it possible to embed sources dynamically. instead of doing this
[Embed(source = '../../../../assets/levels/test.xml')]
I could probably do something like this
var src = '../../../../assets/levels/test.xml'
[Embed(source = src )]
It's not possible for anything within metadata annotations to be dynamic :/. That is, you can't place variables into metadata annotations. If that was possible, there would be SO many cool possibilities. So your first option is the only way to directly embed xml.
You could, however, write a custom metadata parser that figured out how to load (not embed) your xml file. Something like:
[LoadFile]
public var source:String = "../../../../assets/levels/test.xml";
I would implement that like the code below (just wrote this right now, haven't tested it). And then you'd "process" your class via something like MyMetadataUtil.process(this). Lots of ways to do that.
public function extractMetadata(target:Object):void
{
var description:XML = flash.utils.describeType(target);
var tag:String = "LoadFile"
var metadata:XMLList = description.accessor.metadata.(#name == tag);
metadata += description.variable.metadata.(#name == tag);
var i:int = 0;
var n:int = metadata.length();
// usually called a 'directive'
// holds values from metadata annotation
var token:Object = {};
for (i; i < n; i++)
{
metadataXML = metadata[i];
token.property = metadataXML.parent().#name;
// token.source = myClass.source;
token.source = target[token.property];
var request:URLRequest = new URLRequest(token.source);
var loader:URLLoader = new URLLoader();
loader.addEventListener(Event.COMPLETE, loader_completeHandler);
loader.addEventListener(IOErrorEvent.IO_ERROR, loader_ioErrorHandler);
loader.load(request);
}
}
protected function loader_completeHandler(event:Event):void
{
event.currentTarget.removeEventListener(event.type, loader_completeHandler);
trace("SUCCESSFULLY LOADED FILE!");
}
protected function loader_ioErrorHandler(event:Event):void
{
event.currentTarget.removeEventListener(event.type, loader_ioErrorHandler);
}
That stuff would go into some util/manager/processor class. Then anywhere in your code, you could use this:
[LoadFile]
public var source:String = "myFile.xml";
And that could be dynamic. Check out the Swiz Framework for some example source code on how to implement custom metadata processors. Or even better, Openflux's MetaUtil. Once you set that up once, you can do some hardcore stuff in your code. Makes coding fun and fast.
Hope that helps,
Lance
Your use case is basically why I created the ability to add extra frames to Flex SWFs that are treated as late-loaded modules. Instead of embedding your level, stream it in after the main application.
Documentation on -frame is sparse. Sorry! Here's some external stuff, that links back to stuff I wrote and Alex Harui wrote. Good luck!
http://www.richinternet.de/blog/index.cfm?entry=FF295F89-DAD8-CCDC-960413842BC0D478

Get item by index in a tree control

I'm doing a drag and drop operation on a tree using some help from Adobe's quick Starts:
http://www.adobe.com/devnet/flex/quickstart/working_with_tree/
The code suggested is roughly this:
var dropTarget:Tree = Tree(evt.currentTarget);
var i:int = dropTarget.calculateDropIndex(evt);
myTree.selectedIndex = i;
var node:XML = myTree.selectedItem as XML;
var drugXML:XML = XML(Tree(evt.dragInitiator).selectedItem);
if(node.localName() != drugXML.localName()){
DragManager.showFeedback(DragManager.NONE);
return;
}else{
DragManager.showFeedback(DragManager.COPY);
}
This is all well and good, but I don't like the way it is selecting(highlighting) each item in the tree I'm dropping on, it's less clear where the item is going to drop. I want to implement this without the selection but there doesn't seem to be a way to get the XML of the node using just the index. I would like something like this:
var dropTarget:Tree = Tree(evt.currentTarget);
var i:int = dropTarget.calculateDropIndex(evt);
var node:XML = myTree.itemAt(i) as XML;
//AFAIK itemAt(i) or anything like it does not exist
var drugXML:XML = XML(Tree(evt.dragInitiator).selectedItem);
if(node.localName() != drugXML.localName()){
DragManager.showFeedback(DragManager.NONE);
return;
}else{
DragManager.showFeedback(DragManager.COPY);
}
So does anyone know what function is, or what I can do to extend the tree to have a function, like "itemAt(i)"
Thanks
~Mike
EDIT: I forgot to post that my current workaround is setting the selectedIndex = -1 after I get my node:XML. I'm afraid that if something bogs on the processor the user may see it select then deselect.
Much simpler, though there may be gotchas:
var index:int = ...
var renderer:IListItemRenderer = tree.indexToItemRenderer(index);
var item:Object = renderer.data;
This won't work if the index is offscreen (since there might not be an active itemRenderer); shouldn't be an issue for drag and drop.
If your dataProvider is explicitly or implicitly a collection (see the linked docs for conversion rules), you should be able to use getItemAt to resolve the index.
It appears that an XML provider will be converted implicitly:
var tree:Tree = ...;
var data:XML = ...;
tree.dataProvider = data; // could just as well be from MXML
var provider:ICollectionView = tree.collection; // tree converted it for us
trace(provider.getItemAt(index));
If you have something other than the convertible types (XML, Array, etc.), you might consider wrapping your dataProvider in an XMLListCollection or what have you to gain access to that method.
The above is aiming in the right direction but missing.
Turns out you don't want the dataProvider since Tree overrides that; you want the collection property (protected). So you could override Tree and provide an indexToItem method to go with the thisToThat methods already present in Tree.

flex get contents of arraycollection as string

I am trying to get the contents of an arraycollection to print out using my debug function (which takes a string). Anyone know how to do this? I would like it would be rather easy but can't seem to find a way...I get the word "Object" printed a lot of the time.
It's a lot cleaner to do:
var str:String = '['+myArrayCol.source.join(', ')+']';
the source property of an ArrayCollection is an Array, so all the usual functions are available.
The following method should get you what you need:
public static function arrayCollectionToString( arr:ArrayCollection ):String
{
var toRet:String = "[";
for each( var obj:Object in arr ) {
toRet += obj.toString() + ", ";
}
toRet += "]";
return toRet;
}
If you stick this in the same class as your debug method, you could then use it as follows:
SomeDebugClass.dbgMessage( SomeDebugClass.arrayCollectionToString( myArrayCollection ) );
Default is allready coma separated
array.toString()
You can use
ObjectUtil.toString(arrayCollection);

Ideas on making a javascript object name unique in ASP.Net?

I've created an ASP.Net user control that will get placed more than once inside of web page. In this control I've defined a javascript object such as:
function MyObject( options )
{
this.x = options.x;
}
MyObject.prototype.someFunction=function someFunctionF()
{
return this.x + 1;
}
In the code behind I've created MyObject in a startup script --
var opts = { x: 99 };
var myObject = new MyObject( opts );
When a certain button in the control is pressed it will call myObject.someFunction(). Now lets say the value of x will be 99 for one control but 98 for another control. The problem here is that the var myObject will be repeated and only the last instance will matter. Surely there's a way to make the var myObject unique using some concept I've haven't run across yet. Ideas?
Thanks,
Craig
Your Javascript like this:-
function MyObject(options) { this.x = options.x; }
MyObject.prototype.someFunction = function() { return this.x + 1; }
MyObject.create(id, options) {
if (!this._instances) this._instances = {};
return this._instances[id] = new MyObject(options);
}
MyObject.getInstance(id) { return this._instances[id]; }
Your startup javascript like this:-
MyObject.create(ClientID, {x: 99});
Other code that needs to use an instance (say in the client-side onclick event)
String.Format("onclick=\"MyObject.getInstance('{0}').someFunction()\", ClientID);
Note the low impact on the clients global namespace, only the MyObject identifier is added to the global namespace, regardless of how many instances of your control are added to the page.
If it is just one value, why not have the function take it as a parameter and build your onclick handler so that it puts the correct value in for each control. If it is more complex than that, then consider making options an array and, for each control, insert the correct options into the spot in the array that corresponds to each particular control. Then pass the proper index into the array into the function.
I do this by using ScriptManager.RegisterClientScriptBlock to register a string as a JavaScript block on the client side. I can then modify my script string using {0}, {1}..,{n} place holders to inject necessary ids. It depends on the structure of your code as to if this is the most elegant fashion, but it works in a pinch. You could then inject variable names using references to Me.ClientID.
You can make the value of "x" static and access it anywhere in the code, such as:
function MyObject( options ) { MyObject.x = options.x; }
MyObject.x = 99; // static
MyObject.prototype.someFunction = function () { return MyObject.x + 1; }
This way you can access MyObject.x anywhere in your code, even without re-instanciating MyObject.
Excellent solution Anthony. The other solutions offered were as good and I did consider them but I was looking for something a little more elegant like this solution.
Thanks!

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