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Target must be an event emitter

MattTenold

I am currently using the Dojo/on and I keep receiving the Error: Target must be an event emitter
http://js.arcgis.com/3.9/
Line 212

error in this function:

function runQuery() {
   var queryTask = new esri.tasks.QueryTask("http://gis.phila.gov/ArcGIS/rest/services/PhilaGov/Police_Incidents_Last30/MapServer/0");
   
   var query = new esri.tasks.Query();
   query.returnGeometry = true;
   query.where = '1=1';
   query.outFields = ["DC_DIST", "POINT_X", "POINT_Y"];
   
   map.on(queryTask, "onComplete", function(featureSet) {

    var cL = new clusterlayerNew({
     displayOnPan: false,
     map: map,
     features: featureSet.features,
     infoWindow: {
      template: new esri.InfoTemplate("${SECTOR}"),
      width: 325,
      height: 100
     },
     flareLimit: 15,
     flareDistanceFromCenter: 20
       });

             map.addLayer(cL);

   });
  };

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DasaPaddock

Try: queryTask.on("complete", function(event) {});

See:
https://developers.arcgis.com/javascript/jsapi/querytask-amd.html#event-complete

MattTenold

I can't do

queryTask.on("complete", function(event) {});

since I am constructing a clusterlayer using the function features from my AMD class "clusterlayerNew." Is there a way to get the features from the function "features" while running after the queryTask is complete?

ReneRubalcava

How about

on(queryTask, 'complete', function(){});

You lost me there, but the execute method returns a Promise, so you can also do.

queryTask.execute(query).then(someFunction);

DasaPaddock

How about this?

function runQuery() {
  var queryTask = new esri.tasks.QueryTask("http://gis.phila.gov/ArcGIS/rest/services/PhilaGov/Police_Incidents_Last30/MapServer/0");

  var query = new esri.tasks.Query();
  query.returnGeometry = true;
  query.where = '1=1';
  query.outFields = ["DC_DIST", "POINT_X", "POINT_Y"];

  queryTask.on("complete", function(event) {

    var cL = new clusterlayerNew({
      displayOnPan: false,
      map: map,
      features: event.featureSet.features,
      infoWindow: {
        template: new esri.InfoTemplate("${SECTOR}"),
        width: 325,
        height: 100
      },
      flareLimit: 15,
      flareDistanceFromCenter: 20
    });

    map.addLayer(cL);

  });
};

MattTenold

I tried both methods. But this won't work either. The main problem is all of my events are handled in my Dojo class. I attached the main html page and the dojo class with the logic that the main page accesses.

function runQuery() {
   var queryTask = new esri.tasks.QueryTask("http://gis.phila.gov/ArcGIS/rest/services/PhilaGov/Police_Incidents_Last30/MapServer/0");
   
   var query = new esri.tasks.Query();
   query.returnGeometry = true;
   query.where = '1=1';
   query.outFields = ["DC_DIST", "POINT_X", "POINT_Y"];
   
   queryTask.on("complete", function(event) {

    var cL = new clusterlayerNew({
     displayOnPan: false,
     map: map,
     features: event.featureSet.features,
     infoWindow: {
      template: new esri.InfoTemplate("${SECTOR}"),
      width: 325,
      height: 100
     },
     flareLimit: 15,
     flareDistanceFromCenter: 20
       });

             map.addLayer(cL);

   });
  };

clusterlayerNew.zip

DasaPaddock

I just noticed that `runQuery` is missing a call to `queryTask.execute(query)`. Can you try adding this before the queryTask.on line?

MattTenold

Tried that also. Didn't work. It keeps saying Target must be an event emitter.

DasaPaddock

Is this code still in the html page?

  on(queryTask, "onError", function(err) {
  alert(err.details);
  });

  queryTask.execute(query);

Can you remove it since outside the runQuery function, queryTask is the esri/tasks/QueryTask module rather than an instance of a QueryTask.

MattTenold

Tried that. It runs but it keeps jumping around. It doesn't go through the functions. It is really weird. I set a break point but it won't step through the functions. I am still looking for why it doesn't continue running through the functions.

ReneRubalcava

Ok, I got this working, somewhat, but I'll get to that.

This works.

require([
    "dojo/Evented",
    "dojo/ready",
    "dojo/parser",
    "dojo/on",
    "extras/clusterlayerNew",
    "esri/map",
    "esri/layers/graphics",
    "esri/layers/FeatureLayer",
    "esri/layers/GraphicsLayer",
    "esri/tasks/QueryTask",
    "esri/tasks/query",
    "dijit/layout/BorderContainer",
    "dijit/layout/ContentPane",
    "dojo/domReady!"
  ],
  function (
    Evented,
    ready,
    parser,
    on,
    ClusterlayerNew,
    Map, // you had lower-case map, which can cause problems when creating a map variable
    graphics, // This is an empty object because it is not a module
    FeatureLayer,
    GraphicsLayer,
    QueryTask, // was called queryTask, biggest issue
    Query,
    BorderContainer,
    ContentPane
  ) {

    var map;
    // scope this out here. The above had same name (case matters).
    var queryTask = new QueryTask("http://gis.phila.gov/ArcGIS/rest/services/PhilaGov/Police_Incidents_Last30/MapServer/0");


    function init() {
      parser.parse();

      map = new Map("map", { // You had map = new map(), this could cause issues, probably in IE, everything breaks in IE.
        center: [-75.1700, 39.9500],
        zoom: 12,
        basemap: "hybrid"
      });
      runQuery(); // you need the map in the runQuery method, so initialize it first then do runQuery
    }

    function runQuery() {
      var query = new Query();
      query.returnGeometry = true;
      query.where = '1=1';
      query.outFields = ["DC_DIST", "POINT_X", "POINT_Y"];

      queryTask.on("complete", function (event) {
        console.debug('ClusterlayerNew is an empty object?', ClusterlayerNew);
        // This clusterlayer module is broken, it returns an empty object, even after I quickly edited it.
        // I did not try troubleshooting this
        var cL = new ClusterlayerNew({
          displayOnPan: false,
          map: map,
          features: event.featureSet.features,
          infoWindow: {
            template: new esri.InfoTemplate("${SECTOR}"),
            width: 325,
            height: 100
          },
          flareLimit: 15,
          flareDistanceFromCenter: 20
        });

        map.addLayer(cL);

      });
      // you were trying to execute this outside the scope of the function the query was defined in.
      queryTask.execute(query); 
    };

    // before, this was the class "QueryTask", the class is not initialized, thus not an event emitter.
    on(queryTask, "error", function (err) {
      alert(err.details);
    });

    // Use the ready() method as opposed to dojo.addOnLoad
    ready(init);
  });

See my comments for some of the issues you had.

One of your main issues seems to be with scope, so I would run through some material and you'll soon see where things broke.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions_and_function_scope

Don't mix the old dojo.lib.ClassName() with the AMD loading of modules. In this case, it probably just added to the confusion.
Note - Mixing the two won't necessarily break your code (yet), but it should be avoided fro consistency.
That clusterlayerNew module is broken or something, I couldn't get it to work, but my changes above load your map and at least try to create that cluster layer.

You may want to check out a project I have been working on to do clusters in a fashion more similar to a FeatureLayer.
https://github.com/odoe/esri-clusterfeaturelayer

Hope that helps a bit.

MattTenold

Cool. Thank you soo much Odoe. The clusterlayerNew.js isn't soo much of a big deal. I am going to have to use use a json feed anyways which means I will have to modify the clusterlayerNew.js class alot.

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