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Widget Communication Explained

RobertScheitlin__GISP

All,

I have answered many threads where people are attempting to communicate between widget. So I thought that I would document in detail this previously undocumented portion of the Flex Viewer. In this PDF I explain what happens behind the scenes and provide code examples of what you need to add to your widgets. I also provide code for launching a widget from another widget so you can call a particular public function in the second widget. I hope this helps many.

Widget Communication.pdf

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SeanHarkins

Not sure if this thread is the appropriate spot for this question, but I figured I would try here so I might get Robert's assistance. I have Widget A, which when its processing is complete opens Widget B. Using the recommendations from Robert's great Widget Communication document I use the following code to accomplish this. From Widget A

var id_B:Number = ViewerContainer.getInstance().widgetManager.getWidgetId("B");
var baseWidget_B:IBaseWidget = ViewerContainer.getInstance().widgetManager.getWidget(id_B, true) as IBaseWidget;

This works correctly and Widget B opens. However, with a new requirement, when Widget A has completed its processing I also need to open Widget C. I use the following code

var id_B:Number = ViewerContainer.getInstance().widgetManager.getWidgetId("B");
var baseWidget_B:IBaseWidget = ViewerContainer.getInstance().widgetManager.getWidget(id_B, true) as IBaseWidget;
var id_C:Number = ViewerContainer.getInstance().widgetManager.getWidgetId("C");
var baseWidget_C:IBaseWidget = ViewerContainer.getInstance().widgetManager.getWidget(id_C, true) as IBaseWidget;

Now, Widget C opens correctly, but Widget B no longer does. It seems that I can only dispatch a single WIDGET_RUN event from Widget A. If I comment out the code for opening Widget C, Widget B opens correctly. I'm fairly new at developing with the Viewer so any insight on this behavior would be greatly appreciated.

Anonymous User

Thanks Robert! That did the trick! Much appreciated!

RobertScheitlin__GISP

Bob,

Here is some code that you could put in widget B to test if widget A is open and if it is close it:

for each (var widgetId:Number in ViewerContainer.getInstance().widgetManager.getAllLoadedWidgetIds())
{
    if(ViewerContainer.getInstance().widgetManager.getWidget(widgetId).widgetTitle == "WidgetA")
    AppEvent.dispatch(AppEvent.WIDGET_CLOSE, widgetId);
}

Anonymous User

Exactly! And vice versa so that the two widgets remain mutual exclusive ...

RobertScheitlin__GISP

Bob,

So what you are looking for is when widget A opens widget B closes?

Anonymous User

Robert -

Thank you for your quick response. Given that the code block provided seems to end up having the desired result of launching the second widget if it's not already open, is there any other means of toggling 2 widgets visibility that you could recommend? Thanks again for any suggestions you might have.

- Bob

RobertScheitlin__GISP

Bob,

All the openWidgetIfNot parameter does is if the widget is in a minimized state and the openWidgetIfNot is set to also then it does not set the widgets state to maximized/open.

Anonymous User

Robert -

I found your document on inter-widget communictation very useful. However, I get an odd result when I use the following code in an attempt to toggle 2 widgets:

var Widgetw:IBaseWidget = ViewerContainer.getInstance().widgetManager.getWidget(2, false) as IBaseWidget;

which returns null (as expected) if Widget2 isn't yet open, but the problem is that it ends up launching Widget2 despite the 2nd parameter being set to false. Any ideas?

- Bob

JamesKo

Robert,

Thanks for the quick response...I was getting the following error message:
Access of possibly undefined property 'myPublicVar' through a reference with static type com.esri.viewer.IBaseWidget.

BUT I just added these lines of code to get it working:

var vSW:* = bWidget;
var whatever:String = vSW.myPublicVar;

Thanks again.

RobertScheitlin__GISP

James,

I hope that the widget would be loaded already... If that is the case then all you need to do is add these lines to the index.mxml

var id:Number = ViewerContainer.getInstance().widgetManager.getWidgetId("Your Widget");
var bWidget:IBaseWidget = ViewerContainer.getInstance().widgetManager.getWidget(id,true) as IBaseWidget;
x = bWidget.yourPublicVar;

JamesKo

Hi Robert,

This is has been very helpful but I have another related question. How does one access a variable within a widget from the root application, say index.mxml. I want to save a sharedObject based on a value in a widget.

Thanks in advance.

James

azgis

Robert,

That was it! Thanks again for all of your help.

Jim Faron

RobertScheitlin__GISP

Jim,

Sorry about that if the fetchAllData is going to work than we have to actually send something using the addSharedData instead of null.

var msArr:ArrayCollection = new ArrayCollection();
                        msArr.addItem("export");
addSharedData("Legend_exportImage",msArr);

azgis

Robert,

In the Dynamic Legend widget init, I have it as follows:

AppEvent.addListener(AppEvent.DATA_PUBLISH, sharedDataUpdated);
    AppEvent.addListener(AppEvent.DATA_SENT, sharedDataUpdated2);
    fetchSharedData();

Thanks,
Jim Faron

RobertScheitlin__GISP

Jim,

Which event listener is calling the sharedDataUpdated2 function and are you calling the fetchSharedData in the init function of the dynamic legend widget?

AppEvent.addListener(AppEvent.DATA_SENT, sharedDataUpdated2);
                fetchSharedData();

azgis

Robert,

Thanks for the advice, but I can't seem to get the necessary exchange of data to happen. I added:

private function incLegend():void
   {
    if(incLgnd.selected)
    {
     addSharedData("Legend_exportImage",null);
     var id:Number = ViewerContainer.getInstance().widgetManager.getWidgetId("Dynamic Legend");
     var bWidget:IBaseWidget = ViewerContainer.getInstance().widgetManager.getWidget(id,true) as IBaseWidget;

and then in the Dynamic Legend added:

private function sharedDataUpdated2(event:AppEvent):void
   {
    var dataTable:Hashtable = event.data as Hashtable;
    if(dataTable.containsKey("Legend_exportImage"))
    {
      exportImage();
    }
   }

When I debug, the dataTable key in the SharedDataUpdated2 is null. I fire the event listeners on init in the Dyanamic Legend.

Thanks,
Jim Faron

RobertScheitlin__GISP

Jim,

The issue is that if the widget you are calling is not already loaded it takes some time to load and thus the bWidget is going to return null. One way to get around this is to use:

addSharedData("Legend_exportImage", null);

and implement the part of the document under figure 1.

azgis

Robert,

I am encountering a problem with getting the base widget returned. I have set up function triggered by a checkbox in the Print widget to include the Dynamic Legend. The Dynamic Legend opens as expected, but the code

 if(bWidget)

returns null when I debug, and of course anything after it does not happen. Here is the code I am using

private function incLegend():void
   {
    if(incLgnd.selected)
    {
     var id:Number = ViewerContainer.getInstance().widgetManager.getWidgetId("Dynamic Legend");
     var bWidget:IBaseWidget = ViewerContainer.getInstance().widgetManager.getWidget(id,true) as IBaseWidget;
     if(bWidget){
      var vSW:* = bWidget;
      vSW.exportImage();}

Is there something basic that I am missing?

Thanks,
Jim Faron

RobertScheitlin__GISP

Frank,

All is good, but to clarify on the first code block if you are not going to call a public function on the widget than there is no need to get the base widget returned to you.

var id:Number = ViewerContainer.getInstance().widgetManager.getWidgetId("Widget B"); 
AppEvent.dispatch(AppEvent.WIDGET_RUN, id);

The above code is cleaner if you are not calling a function on the widget.

FrankRoberts

Ok, Got it, your right it doesn't have that function, so of course it would fail. So technically, if I just want to launch another widget, from widget "A" I just need this code:

var id:Number = ViewerContainer.getInstance().widgetManager.getWidgetId("Widget B");
var bWidget:IBaseWidget = ViewerContainer.getInstance().widgetManager.getWidget(id, true) as IBaseWidget;

Then if I want to pass values between the two I just need the following in Widget A:

var msArr:ArrayCollection = new ArrayCollection();
//Add an object or for example a string to the ArrayCollection
msArr.addItem("Text to pass to Widget B");    
addSharedData("MiniSearch_Search", msArr);

And then I can drop this code from Widget A, since I'm not calling a function:

if (bWidget){
var vSW:* = bWidget;
vSW.queryFromURL("aaa",2,0);
}

If I'm wrong feel free to set me straight.

Thanks yet again!

RobertScheitlin__GISP

Frank,

So does the FrEditIncidentWidget have a public function called queryFromURL?

FrankRoberts

Robert per the document I implemented the code as follows to open up a widget

var id:Number = ViewerContainer.getInstance().widgetManager.getWidgetId(incidentCreateWidget);
    var bWidget:IBaseWidget = ViewerContainer.getInstance().widgetManager.getWidget(id, true) as IBaseWidget;
    if (bWidget){
     var vSW:* = bWidget;
     vSW.queryFromURL("aaa",2,0);     
    }

In the above "incidentCreateWidget" is a string variable that is set from the xml for the widget.

It works great the first time the code is run (I'm running it from a button click event), however on the second time it throws the following error:

ReferenceError: Error #1069: Property queryFromURL not found on widgets.FrEditIncident.FrEditIncidentWidget and there is no default value.

Where "FrEditIncidentWidget" is the widget being called from the first one, where the code resides.

Any ideas?
Frank

FrankRoberts

Thanks Robert! I appreciate the time you put into putting this document together for all of us. It will be a great reference!

Frank

NitinBele

Thanks Robert, this is just awasome.
It really had a great insight on Widgets Communication.

Thanks again
Lu.

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