PrintTask uncaught TypeError: Cannot read property 'query' of undefined

[Alexwang]

Hello I was able to generate a thumbnail image using PrintTask from a WAB widget via http://mycomputer:3344/webappviewer/?config=sample-configs/config-demo.json. But after I added the widget to one of my apps using WAB dev edition. i got an error below

Not sure why it worked through the custom widget testing url but didn't work after I added it to my application. Can you please help?

_printTask: null,
_printTaskParams: null,
_thumbnailHeight: 200,
_thumbnailWidth: 200,
_thumbnailDpi: 96,
_thumbnailFormat: 'PNG32',
_templateLayout: "MAP_ONLY",
_preserveScale: false,
_showAttribution: false,
_exportWebMapTaskUrl: 'http://sampleserver6.arcgisonline.com/arcgis/rest/services/Utilities/PrintingTools/GPServer/Export%2...',

_initPrintTask: function(){
      this._printTask = new PrintTask(this._exportWebMapUrl);
      var template = new PrintTemplate();
      var params = new PrintParameters();

template.exportOptions = {
   width: this._thumbnailWidth,
   height: this._thumbnailHeight,
   dpi: this._thumbnailDpi
};

template.format = this._thumbnailFormat;
template.layout = this._templateLayout;
template.preserveScale = this._preserveScale;
template.showAttribution = this._showAttribution;

params.map = this.map;
params.template = template;

        this._printTaskParams = params;
},

_createThumbnail: function(){

this._printTask.execute(this._printTaskParams, lang.hitch(this, function(result){
      this._storeThumbnailUrl(result.url);
}));

},

[RobertScheitlin__GISP]

Alex,

   You included some code and a screen capture of the error but that is still not enough for me to figure out the error. Can you provide more?

[Alexwang]

Thanks Robert. My fault, I used the wrong name for the PrintTask url. I was able to make it work now. 

Another question i observed was that the ArcServer GP service keeps the map images only for a short time. Can I change somewhere on ArcServer side to keep the thumbnail images longer? Basically my widget uses a reference to link to these thumbnail images. 

[RobertScheitlin__GISP · Accepted solution]

Alex,

   You have to edit your ArcGIS Servers "Site" page and find the output directory and change the max file age (default 10 minutes).