I have a Flex application that I'm working on for a new job. It's sort of a training wheels application -- I'm learning the language, and this isn't an app that needs to talk to a service in order to do its job. There are a few instances of combo boxes throughout the application that share the same set of possible values (say, a selection of states: "In Progress", "Rejected", "Complete") that I want to have use the same data source.
What is the best way to manage this?
MVC architecture ....well in simple cases just the Model part:
package
{
[Bindable]
public final class ShellModelSingleton
{
public var selectedStatus:ArrayCollection;
////////////////////////////////////////////
// CONSTRUCTOR
// ****DO NOT MODIFY BELOW THIS LINE*******
///////////////////////////////////////////
public function ShellModelSingleton(){}
/****************************************************************
* Singleton logic - this makes sure only 1 instance is created
* Note: you are able to hack this since the constructor doesn't limit
* a single instance
* so make sure the getInstance function is used instead of new
* ShellModelSingleton()
*****************************************************************/
public static function getInstance():ShellModelSingleton {
if(_instance == null) {
_instance = new ShellModelSingleton();
}
return _instance;
}
protected static var _instance:ShellModelSingleton;
}
}
Then you can update and use the singleton from any component like this:
[Bindable] private var model:ShellModelSingleton =
ShellModelSingleton.getInstance();
Component 1
<mx:DataGrid id="myDG" dataProvider="{model.selectedStatus}" />
Component 2
<mx:List id="myList" dataProvider="{model.selectedStatus}"
labelField="label" />
Then any changes you make to the selectedStatus collection will be updated in both components.
Just initialize them to an array in our parent component.
Related
UPDATE 2: FIXED THE CODE at the end
I have the abp.io service below with 2 parameters in the constructor instantiated via DI.
One of them, IOutcomeWriter, has 2 implementations.
I'd like to define at runtime which of the implementations of IOutcomeWriter to use.
This is the main service:
public class UCManagerService
: DomainService, IUCManagerService, ITransientDependency {
private readonly IUCInputReader _inputReader;
// This field can have 2 or 3 implementations.
private readonly IOutcomeWriter _outcomeWriter;
public UCManagerService(
IUCInputReader inputReader, IOutcomeWriter outcomeWriter) {
_inputReader = inputReader;
_outcomeWriter = outcomeWriter;
}
public async Task ExecuteAsync() {
// start processing the input and generate the output
var input = _inputReader.GetInput());
// do something
// ...
_outcomeWriter.Write(something);
}
}
The main service is registered in the AbpModule together with with IUCInputReader and the 2 implementations of IOutcomeWriter:
[DependsOn(
typeof(SwiftConverterDomainModule),
typeof(AbpAutofacModule) // <= use Autofac in some way (I don't know how)
)]
public class ProgramAppModule : AbpModule {
public override void ConfigureServices(ServiceConfigurationContext context) {
context.Services.AddTransient<IUCManagerService, UCManagerService>();
context.Services.AddTransient<IUCInputReader, UCInputReader>();
// 2 implementations of IOutcomeWriter
context.Services.AddTransient<IOutcomeWriter, OutcomeWriter1>();
context.Services.AddTransient<IOutcomeWriter, OutcomeWriter2>();
}
}
What I would like is to instantiate UCManagerService sometimes with OutcomeWriter1 and sometimes with OutcomeWriter2, according to some values in appsettings.json:
IList<JobSetting> jobsToSet = _configuration.GetSection("Jobs")
.Get<List<JobSetting>>();
foreach (JobSetting jobToSet in jobsToSet) {
// If jobsToSet.SomeValue == 'MyValue1' following line should have to
// require a IUCManagerService using OutcomeWriter1. If it is
// 'MyValue2' it'd use OutcomeWriter2, and so on:
var service = abpApplication.ServiceProvider.GetRequiredService<IUCManagerService>(); // ???
// do something else with service
// ...
}
Finally, if a tomorrow I add an OutcomeWriter3 I would just like to register it in ProgramAppModule.ConfigureServices(...) and of course use a different key in appsettings.json.
If I understand correctly, you need the IOutcomeWriter to differ based on the currently executed job. In other words, that means that you need to dynamically switch the writer based on its context.
The fact that it you need to change it dynamically, it means that is not a problem that can be solved solely using your DI configuration, because DI configurations are best kept static.
Instead, you need to mix and match a few concepts. First of all, you need a way to set the used job in the context. For instance:
// DI configuration
services.AddScoped<JobContext>();
// Execution of a job
using (var scope = abpApplication.ServiceProvider.CreateScope())
{
var context = scope.GetRequiredService<JobContext>();
context.CurrentJob = typeof(MyFirstJob);
var job = scope.GetRequiredService<MyFirstJob>();
var job.Execute();
}
In this example, JobContext is a class that holds the data that is used during the execution of a certain job. It is registered as Scoped to allow this data to be available for multiple classes within the same scope.
Now using this new JobContext, you can build an adapter for IOutcomeWriter that can forward the incoming call to the right implementation based on its injected JobContext. This might look as follows:
public class JobSpecificOutcomeWriter : IOutcomeWriter
{
private readonly JobContext context;
private readonly IList<JobSetting> settings;
private readonly IEnumerable<IOutcomeWriter> writers;
public JobSpecificOutcomeWriter(
JobContext context,
IList<JobSetting> settings,
IEnumerable<IOutcomeWriter> writers)
{
this.context = context;
this.settings = settings;
this.writers = writers;
}
// Implement all IOutcomeWriter methods by forwarding them to the
// CurrentWriter.
object IOutcomeWriter.SomeMethod(object a) =>
this.CurrentWriter.SomeMethod(a);
private IOutcomeWriter CurrentWriter
{
get
{
// TODO: Based on the current context and the settings,
// select the proper outcome writer from the writers list.
}
}
}
When JobSpecificOutcomeWriter is injected into UCManagerService (or any component for that matter), it transparently allows the proper writer to be used, without the consuming class from knowing about this.
The tricky part, actually, is to now configure your DI container correctly using JobSpecificOutcomeWriter. Depending on which DI Container you use, your mileage might vary and with the MS.DI Container, this is actually quite complicated.
services.AddTransient<IOutcomeWriter>(c =>
new JobSpecificOutcomeWriter(
context: c.GetRequiredService<JobContext>(),
settings: jobsToSet,
writers: new IOutcomeWriter[]
{
c.GetRequiredService<MyFirstJob>(),
c.GetRequiredService<MySecondJob>(),
c.GetRequiredService<MyThirdJob>(),
});
services.AddTransient<MyFirstJob>();
services.AddTransient<MySecondJob>();
services.AddTransient<MyThirdJob>();
I had study 「Beware of singleton in Flex modules」
in http://www.devahead.com/blog/2010/03/beware-of-singleton-in-flex-modules/
and a lot of information tell me that different module with different content,but in my case it doesn't work!
why the different module use the same static object?
I'm trying to use module wide singleton,but it work like application wide singleton.
Can someone help me how to make module wide singleton.
the short code is like:
<s:Application>
<s:ModuleLoader id="A" creationComplete="loadAModule()"/>
<s:ModuleLoader id="B" creationComplete="loadBModule()"/>
</s:Application>
//-----------AModule
<s:Module>
var aITx:ITx=Tx.newInstant();//Tx extend ITX
tracc(aITx.instantId);
...
</s:Module>
//-----------BModule
<s:Module>
var aITx:ITx=Tx.getInstance();//Tx extend ITX
tracc(aITx.instanceID);
...
</s:Module>
//-----singleton class
public class Tx extends EventDispatcher implements ITx
{
public function Tx()
{
// Add listeners
addEventListeners();
}
private static var instance:Tx;
public static function getInstance():Tx
{
if (!instance)
{
instance = new Tx();
// Generate a random instance ID
instance._instanceID = Math.round(Math.random() * 100);
trace("create new itx id="+instance.instanceID);
}else{
trace("use old itx id="+instance.instanceID);
}
return instance;
}
protected var _instanceID: Number = NaN;
public function get instanceID(): Number
{
return _instanceID;
}
}
I think your problem is related to the context the modules are loaded in. In your case I guess all of your modules are loaded into the same context. In one context there is only one version of one class. Therefore there is only one instance of your Singleton. If you want to have separate classes, you have to load each module into its own context. Have a look at this link which explains the context stuff pretty good: http://livedocs.adobe.com/flex/3/html/help.html?content=05_Display_Programming_33.html
In Flex (Flash Builder 4), I need a way to know if something in an array collection has changed.
I have a custom object:
[Bindable]
public var _myobject:MyObject;
It's basically just a class containing a bunch of different String and Number properties.
I need a reliable way to know if any of the properties have been changed. For example, I am binding the properties to a user interface (fields), but it's also possible for some of the properties to change through code.
Is there a way to do this? I found ChangeWatcher, but that looks like it only looks at a single simple property, such as a String or Number. I need to watch or detect changes in all the properties in my object, hopefully without having to add ChangeWatcher events to every property. Is this possible?
You're probably better off just dispatching binding events on the specific properties you want bindable. Better yet, dispatch a custom binding event, so that all of the things that are bound don't have to filter for "is this the property I care about?" It's really easy with Flash Builder 4.5 to do this, just select your variable name and press Ctrl-1, select "Create getter and setter," select getter and setter and check "Bindable" and "create custom event."
This will create code for you that looks something like this:
private var _yourProperty:String;
[Bindable (event='yourPropertyChange')]
public function get yourProperty():String {
return _yourProperty;
}
public function set yourProperty(value:String):void {
if (value !=== _yourProperty) {
_yourProperty = value;
dispatchEvent(new Event('yourPropertyChange'));
}
}
This will be much less verbose and more performant than the code that Flash Builder generates for you behind the scenes when you just use the Bindable tag on its own.
If you use defined classes as VO/DAO and apply the [Bindable] tag to the class, this will do binding on all properties for you (so long as they are read/write).
Anonymous object detection is difficult at best, let alone adding additional headaches of loosing compiler type checking.
Super basic example: - the key is to tie it to the dispatcher, so internally it can send out the PropertyChangeEvent.
[Bindable]
public class Actor extends EventDispatcher
{
public var fName:String;
public var lName:String;
public var age:uint;
public function get displayName():String
{
return lName +', '+ fName;
}
public function Actor()
{
super();
}
}
public class BindableDictionary extends EventDispatcher {
public function BindableDictionary() {
super();
}
public var dictionary:Dictionary = new Dictionary();
[Bindable("change")]
public function get(key:Object):Object {
return dictionary[key];
}
public function put(key:Object, value:Object):void {
dictionary[key] = value;
dispatchEvent(new Event(Event.CHANGE));
}
}
maybe this class will give you some new idea
I am rather new to flex and am trying to figure out how to listen for a custom event I have created. Let me give you a little background on my app first.
My directory structure is as follows.
assets
components
control
events
model
util
In the model class (which is bindable) I have an ArrayCollection which will get loaded with data via a web service call and a datagrid in a specific component will bind to that ArrayCollection and display the data. The web service is invoked via a button press which initiates the search through an event.
model/ApplicationModel.as
[Bindable]
public class ApplicationModel
{
//put specific model components here
public var data:ArrayCollection;
//the one instance in this Singleton
private static var _instance:ApplicationModel;
public function ApplicationModel()
{
if (_instance != null) throw new Error("ApplicationModel already exists!");
}
public static function getInstance():ApplicationModel
{
if (_instance == null) _instance = new ApplicationModel();
return _instance;
}
}
components/SearchBox.mxml
<mx:HBox xmlns:mx="http://www.adobe.com/2006/mxml">
<mx:Script>
<![CDATA[
import com.homedepot.di.tp.SCVTools.events.*;
private function doSearch():void
{
var query:String = searchTI.text;
//only want to dispatch an event if there is something to query
if (query) dispatchEvent(new CustomEvent(CustomEvent.UPDATE_START,query));
}
]]>
</mx:Script>
<mx:Label text="Enter Search Term"/>
<mx:TextInput id="searchTI" enter="doSearch()" />
<mx:Button label="Search" click="doSearch()"/>
</mx:HBox>
This search functionality works fine and will return the data that I want. What I need to be able to know is when this web service call is done so the view component can update other aspects of the view accordingly (hide columns of datagrid based on the data returned as an example).
My Application.mxml file will wire up my controller to listen for the CustomEvent. The controller will then delegate the work to actually call the web service and get the data. The delegate will create an HTTPService object and get the data. It will also process results of the HTTPService. I am currently trying to dispatch a new event in the function that handles the result of the HTTPService call. This does not seem to be working and it makes sense since the event will never bubble to my view component.
snippet of control/DataUpdateDelegate.as
public override function parse(event:ResultEvent):void
{
super.parse(event);
try
{
Application.debug("DataUpdateDelegate:parse");
var data:Object = event.result.records.record;
model.data = data as ArrayCollection;
dispatchEvent(new CustomEvent(CustomEevent.UPDATE_END) );
}
catch (error:Error)
{
handleError(error);
}
}
I have tried to wire this UPDATE_END event up in the Application.mxml file but that does not seem to work either.
Does anyone have any suggestions on how my view to listen to this event that is not dispatched from a child component but rather from an ActionScript class that knows nothing about the view component?
Thanks,
Thomas
You could bind a specific function to the data property using BindingUtils when your ApplicationModel is first set in your view:
public function set model(applicationModelInstance:ApplicationModel):void
{
_applcationModelInstance = applicationModelInstance;
BindingUtils.bindSetter(dataRefreshed, _applicationModelInstance, "data");
}
protected function dataRefreshed(value:Object):void
{
// do whatever you need to do here.
// value==applicationModelInstance.data
}
De-registering a binding like this to avoid memory leaks is a bit tricky, but since your ApplicationModel is a singleton you don't need to anyways.
I have a dynamic ActionScript Class that is used to send parameters to a WebService. Some of these parameters are always present, so they are public properties of the Class:
package
{
[Bindable]
public dynamic class WebServiceCriteria
{
public var property1:int;
public var property2:String;
public var property3:String;
public var property4:String;
}
}
But, I am also adding properties at runtime that can change over time:
criteria.runTimeProperty = "1";
I'm not very familiar with using dynamic classes, so I was wondering if it is possible to "remove" the new property. Let's say the next time I call the WebService I don't want that property sent - not even as a null. How can I remove it from the Class instance without creating a new instance each time?
I believe all you'd need to do is this:
delete criteria.runTimeProperty;
or
delete criteria["runTimeProperty"];
Either should do the same thing.
See the delete documentation for specifics.