topic Re: Passing Attribute Value to Variable in ArcGIS JavaScript Maps SDK Questions

Passing Attribute Value to Variable

LeviRoberts — Thu, 01 May 2014 14:22:29 GMT

We are trying to set up a simple application that only uses one layer. This layer is a grid for a mapbook. We want users to be able to click one of the grid features and it open a pdf on a separate window. The only thing I'm hung up on currently is trying to grab an attribute value and pass it to a variable. One of the attributes for the feature is the URL to the PDF.

var mapBook = new FeatureLayer("[Webservice]", {  mode: FeatureLayer.MODE_SNAPSHOT  });  map.addLayer(mapBook);  mapBook.on("click", function(evt) {  var url = [Need to pass attribute value here];         window.open(url);  });

Do I need to use Query or Identify task? Or is there something else?

Re: Passing Attribute Value to Variable

JakeSkinner — Thu, 01 May 2014 14:31:42 GMT

Hi Steve,

You could use the following:

mapBook.on("click", function(evt) {           var url = evt.graphic.attributes.<field name>;           window.open(url); });

Simply replace <field name> with the field name that contains the URL.

Re: Passing Attribute Value to Variable

JakeSkinner — Sat, 11 Dec 2021 14:45:03 GMT

One other thing, you will need to specify the outFields parameter for the Feature Layer:

var mapBook = new FeatureLayer("[Webservice]", {
    mode: FeatureLayer.MODE_SNAPSHOT,
    outFields: ["*"]
});

Re: Passing Attribute Value to Variable

LeviRoberts — Thu, 01 May 2014 15:20:56 GMT

Perfect. Works like a charm now. Thanks for your help.

Re: Passing Attribute Value to Variable

MichaelVolz — Thu, 01 May 2014 15:28:45 GMT

Steve:

Have you been able to get your sample to work with Jake's comments?

I tried the sample with other additional required items and it does not work.

Could you post all the code for your sample?

Re: Passing Attribute Value to Variable

JakeSkinner — Thu, 01 May 2014 15:36:00 GMT

Steve,

Could you mark this thread as 'resolved/answered' to help other users in the community?

Thanks!

Re: Passing Attribute Value to Variable

MichaelVolz — Thu, 01 May 2014 17:37:21 GMT

Here is my sample that hopefully someone can see where I am going wrong as I am getting errors and unable to get the attribute from the Feature Layer - I cannot get the app to show the URL value in the line console.log("url = ", url); below:

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    
    <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
    <title>FeatureLayer On Demand</title>

    <link rel="stylesheet" href="http://js.arcgis.com/3.9/js/dojo/dijit/themes/claro/claro.css">
    <link rel="stylesheet" href="http://js.arcgis.com/3.9/js/esri/css/esri.css">
    <style>
      html, body, #mapDiv {
        padding:0;
        margin:0;
        height:100%;
      }
    </style>
    <script src="http://js.arcgis.com/3.9/"></script>
    <script>
      var map;
      require([
        "esri/map", "esri/layers/FeatureLayer",
        "dojo/parser", "dojo/domReady!"
      ], function(
        Map, FeatureLayer,
        parser
      ) {
        parser.parse();
        map = new Map("mapDiv", {
          basemap: "national-geographic",
          center: [-75.56, 40.0025],
          zoom: 10
        });

var parcels = new FeatureLayer("Feature Layer REST endpoint URL", {
   mode: FeatureLayer.MODE_SNAPSHOT,
   outFields: ["*"]
});
console.log("hello");
map.addLayer(parcels);

parcels.on("click", function(evt) {
var url = evt.graphic.attributes.UPI;
   console.log("url = ", url);
    });

      });
    </script>
</head>
<body class="claro">
    <div id="mapDiv">
    </div>
</body>
</html>

Can anyone see what I am doing wrong?

Re: Passing Attribute Value to Variable

JakeSkinner — Sat, 11 Dec 2021 14:45:06 GMT

Hi Mike,

Your code looks correct. Be sure the field you are referencing is 'UPI' and not 'upi'. Here is an example of your code with a sample service:

<!DOCTYPE html>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <!--The viewport meta tag is used to improve the presentation and behavior of the samples
    on iOS devices-->
    <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
    <title>FeatureLayer On Demand</title>

    <link rel="stylesheet" href="http://js.arcgis.com/3.9/js/dojo/dijit/themes/claro/claro.css">
    <link rel="stylesheet" href="http://js.arcgis.com/3.9/js/esri/css/esri.css">
    <style>
      html, body, #mapDiv {
        padding: 0;
        margin: 0;
        height: 100%;
      }
    </style>
    <script src="http://js.arcgis.com/3.9/"></script>
    <script>
      var map;
      require(["esri/map", "esri/layers/FeatureLayer", "dojo/parser", "dojo/domReady!"], function(Map, FeatureLayer, parser) {
        parser.parse();
        map = new Map("mapDiv", {
          basemap : "national-geographic",
          center : [-81.792107, 26.150807],
          zoom : 9
        });

        var parcels = new FeatureLayer("http://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer/0", {
          mode : FeatureLayer.MODE_SNAPSHOT,
          outFields : ["*"]
        });

        map.addLayer(parcels);

        parcels.on("click", function(evt) {
          var url = evt.graphic.attributes.areaname;
          console.log("url = ", url);
        });

      });
    </script>
  </head>
  <body class="claro">
    <div id="mapDiv"></div>
  </body>
</html>

Re: Passing Attribute Value to Variable

KenBuja — Thu, 01 May 2014 18:09:55 GMT

Check the capabilities of your map service. I noticed that when using a service like Jake did, it works fine. However, if I used a service from an older server (http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/3, for example), the click event would never get activated.

Re: Passing Attribute Value to Variable

MichaelVolz — Thu, 01 May 2014 19:15:06 GMT

Jake:

First off thanks for posting my modified sample with your layers.

I have some follow-up questions.

1.) Do you have to use a FeatureLayer to achieve this functionality?

2.) Can you call the data another way as there is by default a 1000 feature limit (This can be increased but it takes a toll on application performance)?

I ask this because I have a feature layer with over 100,000 features and I only saw 1 feature in the map extent I was using which I'm now thinking was because this was the only feature visible in the first 1000 records of the 100,000 record feature layer.

Re: Passing Attribute Value to Variable

JakeSkinner — Fri, 02 May 2014 10:46:03 GMT

1.) Do you have to use a FeatureLayer to achieve this functionality?

You would have to implement another workflow to do this with a dynamic map service layer since the esri/layers/ArcGISDynamicMapServiceLayer module does not have a 'click' event.

2.) Can you call the data another way as there is by default a 1000 feature limit (This can be increased but it takes a toll on application performance)?

In your original code, you are using MODE_SNAPSHOT to load your feature layer. In snapshot mode, the feature layer retrieves all the features from the associated layer resource and displays them as graphics on the client.

You should use MODE_ONDEMAND. In on-demand mode, the feature layer retrieves features from the server when needed.

For more information see the following link:
https://developers.arcgis.com/javascript/jsapi/featurelayer-amd.html