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Deferreds and Identify Task

BrendanDwyer

Asynchronous programming newbie question. I need to run an identify task on a dynamic map service layer. After I get the results of the identify, I need to do another operation before the results are sent to the popup. I'll use that operation to format the infoTemplate.

How do I prevent the popup from displaying until I format it? It seems that as soon as the result comes back, the dojo will display the popup with the returned records. I think I need to chain the deferreds or create a deferred list, but I can't grok how it works.

function executeIdentifyTask(evt) {
identifyParams.geometry = evt.mapPoint;
identifyParams.mapExtent = map.extent;

var deferred = identifyTask.execute(identifyParams);
       deferred.addCallback(function(response) {
          // response is an array of identify result objects
          // Let's return an array of features.
       return dojo.map(response, function(result) {
       var feature = result.feature;
       if(result.layerName === 'Tax Parcels'){
if (blah.length>0) {
FORMAT CONTENT HERE
          var template = new esri.InfoTemplate("", "${Postal Address} <br/> Owner of record: ${First Owner Name}");
          feature.setInfoTemplate(template);
}
else
{
FORMAT CONTENT DIFFERENT WAY HERE
          var template = new esri.InfoTemplate("", "${Different Stuff} <br/> Owner of record: ${Blah}");
          feature.setInfoTemplate(template);
}
});
        console.log(feature.attributes.PARCELID);
       }
       else if (result.layerName === 'Building Footprints'){
        var template = new esri.InfoTemplate("", "Parcel ID: ${PARCELID}");
         feature.setInfoTemplate(template);
        }
        return feature;
        });
     });


        // InfoWindow expects an array of features from each deferred
        // object that you pass. If the response from the task execution
        // above is not an array of features, then you need to add a callback
        // like the one above to post-process the response and return an
        // array of features.
        map.infoWindow.setFeatures([ deferred ]);
        map.infoWindow.show(evt.mapPoint);
      }

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Accepted answers

All comments

Mr_Kirkwood

Kelly,

Quick question:

Do i keep the identify tasks set up the way i have them and then use the promise?

Mr_Kirkwood

Thanks. I will check out that example and let you know if i get it figured out. Thanks!

khutchins

Robert,

There's only one info window so whichever identify finishes last will overwrite the first one with the content. I think instead you'll want to use dojo/promises/all to determine when both identify tasks have finished and then set the info window content. We have a sample in the help that shows how to work with multiple deferreds and dojo/promises/all here:

Manage results from multiple queries | ArcGIS API for JavaScript

Mr_Kirkwood

Kelly,

I am using the deferred method for identify task. i have two services i would like to create tasks for and use info templates for each sub layer. The problem i am having is that it will only identify the last service in the code. in my main application it will identify the 1st layer i turn on that is in the first service. however, when i turn on layers in the second service it will no longer identify layers in the first service.

I created jsfiddle that is a simplified version of my application. Do you have any idea what i am doing wrong here?

Also, I am using this method so i can identify grids/rasters...

Edit fiddle - JSFiddle

BrendanDwyer

Tracy,
Thanks for replying. I thought about doing a check before the infowindow.show method. I don't think that would work.

The problem is that I call the featureLayer.queryAttachmentInfos function inside the deferred.addCallback function. I call this so that I can get the attachement url and create the feature.template with it. I want to display the attached photos in the infowindow.

For some reason, the callback function returns the feature before the queryAttachmentInfo returns. I don't understand this. It's inside the callback function. Should everything inside that function operate synchronously?

If I can get the callback function to wait for the queryAttachmentInfo to finish, I'd be all set. I don't think I can run a test before the onshow method because there might be more than one queryAttachmentInfo method to fire (if more than one features are clicked).

TracySchloss

I'm not sure about the nested deferred, but as far as your infoTemplate content, I've been using a function on it, rather than just defining it like you have. It gave me a lot finer control of it's behavior as opposed to hard coding it and it doesn't try to format the information until the feature was returned from the identify. I wanted the contents displayed as a table. I have a lot of messy attribution, so there are lots of checks in my code to make sure there are values before I add it as a record in the table.

   parcelInfoTemplate = new esri.InfoTemplate();
   parcelInfoTemplate.setTitle("Parcel Information");
   parcelInfoTemplate.setContent(parcelSetWindowContent);

Here's my identify function that I have set to my map 'onClick'

function doIdentify(event){
    map.infoWindow.hide();
    map.graphics.clear();
        labelPt = event.mapPoint;
        parcelIdentifyParams.geometry = event.mapPoint;
        parcelIdentifyParams.mapExtent = map.extent;
    var deferred = parcelIdentifyTask.execute(parcelIdentifyParams);
        
        deferred.addCallback(function(response){
            var feature = response[0].feature;        
            showInfoWindow(feature,labelPt);          
        });
    }
}
function showInfoWindow (feature, labelPt) {
   feature.setInfoTemplate(parcelInfoTemplate);              
   map.infoWindow.setTitle("Parcel Information");
   map.infoWindow.setContent(feature.getContent());
   map.infoWindow.show(labelPt);              
}

function parcelSetWindowContent(graphic) {
    var nameTest1 = graphic.attributes.NAME1;
    var addressTest = graphic.attributes.SITEADDRES;
    var addressTest2 = graphic.attributes.SITEADDRESS;//very freaky that some seem to have one 's' and other two
    var legalTest1 = graphic.attributes.LEGAL1;
    var legalTest2 = graphic.attributes.LEGAL2;
    var legalTest3 = graphic.attributes.LEGAL3;
    var legalTest4 = graphic.attributes.LEGAL4;
    var fullLegalString;
    var twpRangeSecString;
    var twpTest = graphic.attributes.TOWNSHIP;
    var rngTest = graphic.attributes.RANGE;
    var secTest = graphic.attributes.SECTION;
    if (twpTest != 'undefined' && twpTest != 'Null') {
      twpRangeSecString = "TWP:" + graphic.attributes.TOWNSHIP;
    }
    if (rngTest != 'undefined' && rngTest != 'Null') {
      twpRangeSecString = twpRangeSecString +  "  RNG:" + graphic.attributes.RANGE;
    }
    if (secTest != 'undefined' && secTest != 'Null') {
      twpRangeSecString = twpRangeSecString +  " SEC: " + graphic.attributes.SECTION;
   }
    var acreageTest = graphic.attributes.ACRES;
    var buildingNameTest = graphic.attributes.BUILDING_NAME;
    var bookTest = graphic.attributes.BOOK1;
    var pageTest = graphic.attributes.PAGE1;
    var initString = "";//used to see if there is really any content in the attribute values 
    //There is problem with Null being detected as a 4 character length string instead of just nothing
    //checking to see if the value is longer than 4 characters because of this
   
    initTable = "<table id='infoWindowTable' data-dojo-type='dojox.grid.DataGrid' class='infoTable' ><tr><th></th><th></th></tr>"; 
       if (nameTest1.length > 1) {
        initTable = initTable + "<tr><td><b>Owner:</b></td><td>" + nameTest1+ "</td></tr>";
        initString = nameTest1;
    }
    if (buildingNameTest) {
        if (buildingNameTest.length > 4) {
            initTable = initTable + "<tr><td><b>Building:</b></td><td>" + buildingNameTest+ "</td></tr>";
            initString = initString + buildingNameTest;
        }
    }
    if (addressTest) {
        if (addressTest.length > 4) {
            initTable = initTable + "<tr><td><b>Site Address:</b></td><td>" + addressTest + "</td></tr>";
            initString = initString + addressTest;
        }
    }
        if (addressTest2) {
        if (addressTest2.length > 4) {
            initTable = initTable + "<tr><td><b>Site Address:</b></td><td>" + addressTest2 + "</td></tr>";
             initString = initString + addressTest2;
        }
    }
   initTable = initTable + "</table><br><a id='btnZoom'  onClick='zoomTo();'>Zoom To</a>";
   
  //some counties provided so little information in a field that there wasn't enough information to put 
  //in an infoWindow
  if (initString.length < 3) {
     initTable = "Limited data provided, see side panel.";
  }
  return initTable;
}

Maybe it will at least give you some ideas of another way to approach your problem.

BrendanDwyer

One option might be to just add the layers you want to query to your application as feature layers in Selection only mode. When you add each feature layer define the info template for that layer. Note that in this example we don't have to query for attachment info because we've set showAttachments to true when defining the info template for the feature layer that has attachments. Then when you click the map you can use the feature layer's selectFeatures method to select the features of interest and display them in the popup.

Here's a jsfiddle that shows this:

http://jsfiddle.net/Wav9r/

Kelly, thanks for posting. I've actually implemented your solution as I've tried to work out the problem. The hangup is that I have to run the identify over many, many layers (hundreds, actually. Don't ask: Customer wants it this way....). I'd have to add each feature layer individually and then specify an identify task for each, correct?

Is there a way to hold up the function from returning the feature until the queryattachmentinfo returns it's data? I think I need to nest the deferreds, but as I said, I'm not tracking how to do it. I've tried a couple of different ways and it's not working.

khutchins

One option might be to just add the layers you want to query to your application as feature layers in Selection only mode. When you add each feature layer define the info template for that layer. Note that in this example we don't have to query for attachment info because we've set showAttachments to true when defining the info template for the feature layer that has attachments. Then when you click the map you can use the feature layer's selectFeatures method to select the features of interest and display them in the popup.

Here's a jsfiddle that shows this:

http://jsfiddle.net/Wav9r/

BrendanDwyer

Here's an example of using a DeferredList to await for the results of two different IdentifyTasks.

Ken, thanks for the reply but I don't think it applies to my situation. I need to do the following:

Set off an identify task
For each record that comes back (in the result array), get the objectID and the layer id.
Create a feature layer (concatenating a set url string with the layer id)
Run the queryAttachemntInfos function on the feature layer and the objectID
Configure the infoTemplate for each record based on what comes back from queryAttachementInfos.

So I think I need nested deferreds. I attached a txt file to this post. You need to change the extension from .txt to .html. Where its going wrong is in the executeIdentifyTask function. I'm trying to nest the deferreds but it doesn't look like I'm setting up the callback right. Any ideas?

popupTest2.txt.zip

kenbuja

Here's an example of using a DeferredList to await for the results of two different IdentifyTasks.

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