i'm trying to access an mxml component from my external as file. e.g
main.mxml:<br>
<code>[mx:text id="myText" />]</code>
file.as:<br>
<code>var mainM:main = new main();
mainM.text.visible = true;</code>
I get the following error:
[TypeError: Error #1009: Cannot access a property or method of a null object reference]
Any suggestions on how to approach it better.
The ID of your component instance becomes a member of your application and can easy be accessed like so
import mx.core.Application;
mx.core.Application.application.myText.visible = true;
An additional answer is that when you create a new Flex component (new myFlexComponent()), the child UI components are not created until a CREATION_COMPLETE call is invoked, indicating the component is fully created. In the case of application, there is only one, and its automatically created by the framework, and referenced by (Application.application) as stated above.
For example, if your variable was a simple class variable (e.g. myDate:Date), you could access it via the above syntax
Related
My main application contains a ClassA. The main application then loads a module and in that module I would like would to do:
var classA:InterfaceClassA = new ClassA();
It compiles fine but I get this warning:
Warning: YourApplication is a module or application that is directly referenced. This will cause YourApplication and all of its dependencies to be linked in with module.YourModule:Module. Using an interface is the recommended practice to avoid this.
I can't use an interface to generate the new instance, so what is the correct way to do this?
I found an answer in Accessing the parent application from the modules . I created a helper class in the main Application that contains instances of the classes I want to access. In the module I then use:
parentApplication.myModuleHelper.**myClassInstance**.myMethod();
for instance methods and for static class level methods I use:
parentApplication.myModuleHelper.**MyClassInstance**.myMethod()
To get an instance of my class in a module I use this in MyModuleHelper
public function getFullScreenUtil(iFullScreenUtil:IFullScreenUtil , iSystemManager:ISystemManager):FullScreenUtil {
return new FullScreenUtil(iFullScreenUtil , iSystemManager);
}
and this in MyModule:
var _fullScreenUtil:* = parentApplication.moduleHelper.getFullScreenUtil(this , systemManager);
which is all I need for now. I am not sure how I could cast the result of getFullScreenUtil(..) to an actual instance of FullScreenUtil but I expect that it can not be done in modules. Maybe using an interface would provide the solution to that.
My application currently contains a number of Widgets that are managed by a Widget Manager. When the user clicks on a widget (e.g. a Helper widget), the Widget Manager loads the widget into a separate sibling application domain with the following line of code:
wgtInfo.load(null, null, null, moduleFactory); //wgtInfo = IModuleInfo
However, I am unable to use the widget's variables and functions later on. I attempt to find the Helper widget from the Widget Manager's list of widgets, and I do successfully. But when I try to caste the Helper Widget from type IBaseWidget (the interface all widgets share) to type HelperWidget, I receive the following error:
TypeError: Error #1034: Type Coercion failed.....
This is because the application domain of the class trying to use the Helper widget is different from the application domain of the Helper Widget. I tried to fix this by loading all widgets into the same application domain as the loader:
wgtInfo.load(ApplicationDomain.currentDomain, null, null, moduleFactory);
I now get the following error whenever I attempt to load the Helper widget:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
How can I load my Helper widget into a common application domain that is accessible by the other widgets?
I believe your problem comes from the class not being included in the swf. This is because Flash doesn't compile in classes in a swf if they aren't used to reduce filesize. To prevent this, you only need to create a variable with the helper class you need in that class, like this:
private var helper:HelperWidget;
See if that helps.
I'm gonna repost my 'comment' as a real answer. I'm guessing that the error is not based on the ApplicationDomain but based on which classes you are being compiled into your Module. When Flex compiles the SWF it automatically optimizes unused classes out of the SWF. You can force them back into the SWF in one of two ways:
Use the compiler argument include-libraries to force the Flex compiler to add the class to your SWF.
Add a fake variable in in your application so that the Flex compiler thinks it is used and adds it to the final SWF. Something like this.
private var myFakeObject : HelperWidth;
After trying a number of solutions unsuccessfully (including the other responses on this page), I resorted to another, event-driven, solution.
I ended up dispatching a custom event to notify my other widgets when the Helper widget had completed loading:
(HelperWidget.mxml)
ViewerContainer.addEventListener(AppEvent.WIDGET_OPEN_TAB, widgetOpenTabHandler); //listen for other widgets to open a tab within the Helper Widget
ViewerContainer.dispatchEvent(new AppEvent(AppEvent.WIDGET_READY_OPEN_TAB)); //notify other widgets that loading is complete
My other widgets listen for this event to fire, and upon completion, dispatch another event (AppEvent.WIDGET_OPEN_TAB) to perform a function within the Helper widget.
This is my first time here, but I already found some good answers here, so I'd like to thank everyone.
I'm developping a small Flex application and I want to instantiate every class from a package into an array, so I can parse it afterwards. To clarify, I'm trying to ease a plugin management system for my application, with the old canProcess/doProcess routine :
My plugins are all in ONE package, including an abstract plugin class. First, I create one instance of every classes in this package (that's where I need help) and put them in an array. Then, whenever I need a plugin for an item, I parse every plugin class in my array with the canProcess method (the item is the parameter). If one plugin says yes, then I send the item to the doProcess method and stop parsing the array.
I know I could implement by hand every class in my package, but I'd prefer not bothering to do it.
Has anyone an idea ?
Thx
AS3 reflection doesn't allow you to list all classes in a package. You will have to write the class names to an (xml) file at the server, load it and then use getDefinitionByName to get Class objects from those strings and then instantiate them.
Consider the sample xml file:
<root package="boris.ratak">
<className>Plugin1</className>
<className>Plugin2</className>
<className>Plugin3</className>
</root>
load it with URLLoader and parse it like:
import flash.utils.getDefinitionByName;
var pack:String = String(xml.#package) + ".";
for each(var cl:String in xml.className)
{
var name:String = pack + String(cl.text());
var Type:Class = getDefinitionByName(name) as Class;
pluginArray.push(new Type());
}
In my flex app there are a few custom components. I want to create instance of these components at runtime and assign them properties by reading in a config file.
I know how to read xml and instantiate components, however my question is about being able
to get the type of the component from the xml attribute and then creating an instance of that type.
My xml looks like this:
You can instantiate an arbitrary named type through ActionScript's "reflection API":
var clazz:Class = Class(getDefinitionByName("class.from.your.xml.file.Name"));
var component:Object = new clazz();
http://livedocs.adobe.com/flex/3/langref/flash/utils/package.html#getDefinitionByName()
If you get an error about the type not existing, this is because it isn't linked from elsewhere in your application and the compiler only adds classes that are referenced. You can work around this using the following compiler arg:
includes class [...]
Links one or more classes to the resulting application SWF file, whether or not those classes are required at compile time.
http://livedocs.adobe.com/flex/3/html/compilers_14.html#157203
I have an FLA file with objects in the library which I have set to be "classes" (In CS3, right click an item in the library select properties, make sure it's set to export for action-script, and has a class name)
For this exercise, let's call the class "MyClass"
If I publish that FLA to an SWC and SWF:
I can load the SWC statically, and instantiate "MyClass" by simply doing:
var inst:MyClass = new MyClasS();
Now, the problem: I'd like to be able to do this at runtime by loading the SWF file using a loader object.
I understand how to access instances which have been created by hand in the FLA before publishing, but what I want to be able to do, is create new instances of the class "MyClass".
I can get a "MovieClip" representing the swf file, I can add it to my displaylist, but I can't seem to get at the classes contained therein. (I hope this makes sense)
Any suggestions for how to attack this would be much appreciated.
Edit : Format code
To complete Christian's answer:
var cls : Class = loader.contentLoaderInfo.applicationDomain.getDefinition("ClassName");
var instance : Object = new cls();
Additionally, it's worth noting that you won't get strong typing (ie. it must be declared as Object) unless the class implements interface which is also defined in your main application. You will then be able to declare the instance variable as the interface and have compile-time access to it's members.
Have a look here; you should be able to extract a class reference by using Loader.contentLoaderInfo.applicationDomain.getDefinition("MyClass").