topic Map Tool Tip and Null Values in ArcGIS API for Flex Questions

Map Tool Tip and Null Values

ionarawilson1 — Wed, 28 Mar 2012 18:28:19 GMT

I am working on a web application that has two combo boxes, one for year (called yearcombo) and for measures (called myURL) for that selected year. I have two years and a bunch of measure for each year.I want to create a tool tip that when you mouse over the county you see a measure for that specific year. However the feature layer has null values and when I click on counties with null values, I get an error. Here is the error when I click on the null value:

TypeError: Error #1009: Cannot access a property or method of a null object reference.

And here is the code snippet so far

f (yearcombo.selectedItem.year == "2007" && myURL.selectedIndex == 0)
{
fLayer.definitionExpression = "DATA_YEAR_TXT like '2007'"

var graphic:Graphic = Graphic(event.currentTarget);
var htmlText:String = graphic.attributes.htmlText;
var textArea:TextArea = new TextArea();
textArea.htmlText = "Measure: " + graphic.attributes.ForDirIndOut.toString()
myMap.infoWindow.content=textArea
myMap.infoWindow.label = graphic.attributes.NAME;
myMap.infoWindow.closeButtonVisible = false;
myMap.infoWindow.show(myMap.toMapFromStage(event.stageX, event.stageY));
}

else if (yearcombo.selectedItem.year == "2009" && myURL.selectedIndex == 0)
{
fLayer.definitionExpression = "DATA_YEAR_TXT like '2009'"
var graphic2:Graphic = Graphic(event.currentTarget);
var htmlText2:String = graphic2.attributes.htmlText;
var mytextArea2:TextArea = new TextArea();
mytextArea2.htmlText2 = "Measure: " + graphic2.attributes.ForDirIndOut.toString()
myMap.infoWindow.content=mytextArea2
myMap.infoWindow.label = graphic2.attributes.NAME;
myMap.infoWindow.closeButtonVisible = false;
myMap.infoWindow.show(myMap.toMapFromStage(event.stageX, event.stageY));
}

Any ideas on how I can get rid of the error message? Thank you!

Re: Map Tool Tip and Null Values

RobertScheitlin__GISP — Thu, 29 Mar 2012 02:14:31 GMT

Ionara,

To avoid the null value you would do a simple line like this:

textArea.htmlText = "<b>Measure: </b>" + (graphic.attributes.ForDirIndOut)?graphic.attributes.ForDirIndOut.toString():"";

and use this same pattern anytime you check the graphic for a particular attribute.

Re: Map Tool Tip and Null Values - Error thrown by event

ionarawilson1 — Thu, 29 Mar 2012 13:45:06 GMT

To answer my own question I used try and catch methods and it worked. I just dont understand why it didnt trace the error as my method asks it to be traced but the error is not appearing anymore. See code below


    if (yearcombo.selectedItem.year == "2007" && myURL.selectedIndex == 0)
    {
     fLayer.definitionExpression = "DATA_YEAR_TXT like '2007'"

     var graphic:Graphic = Graphic(event.currentTarget);
     graphic.symbol = mouseOverSymbol;
     var htmlText:String = graphic.attributes.htmlText;
     var textArea:TextArea = new TextArea();

     try{
     textArea.htmlText = myURL.selectedItem.label + graphic.attributes.ForDirIndOut.toString()
     myMap.infoWindow.content=textArea
     myMap.infoWindow.label = graphic.attributes.NAME;
     myMap.infoWindow.closeButtonVisible = false;
     myMap.infoWindow.show(myMap.toMapFromStage(event.stageX, event.stageY));}

     catch(error:Error) {
      trace("Caught Error: "+error);
     }

Re: Map Tool Tip and Null Values

ionarawilson1 — Thu, 29 Mar 2012 18:02:04 GMT

Thank you Robert, you always have great solutions! I am going to try that!

Re: Map Tool Tip and Null Values

ionarawilson1 — Thu, 29 Mar 2012 18:23:07 GMT

Hi Robert,

I tried that and still got the same error. Any ideas?

Here is the code snippet

 if (yearcombo.selectedItem.year == "2007" && myURL.selectedIndex == 0 && radioBtnGroup.selectedValue == 0)
 {
 fLayer.definitionExpression = "DATA_YEAR_TXT like '2007'"

 var graphic:Graphic = Graphic(event.currentTarget);
 graphic.symbol = mouseOverSymbol;
 var htmlText:String = graphic.attributes.htmlText;
 var textArea:TextArea = new TextArea();
 textArea.htmlText = "Measure: " + (graphic.attributes.ForDirIndOut)?graphic.attributes.ForDirIndOut.toString():"";
 myMap.infoWindow.content=textArea
 myMap.infoWindow.label = graphic.attributes.NAME;
 myMap.infoWindow.closeButtonVisible = false;
 myMap.infoWindow.show(myMap.toMapFromStage(event.stageX, event.stageY));}

Re: Map Tool Tip and Null Values

RobertScheitlin__GISP — Thu, 29 Mar 2012 19:55:39 GMT

Ionara,

You need to check the existence of any attribute that you attempt to use.

var htmlText:String = (graphic.attributes.htmlText)?graphic.attributes.htmlText:"";