Graphic within GraphicLayer is undefined.

[DavidKucharski]

I have a graphics layer that has a graphics length of 2 because I added 3 graphics. When I try to reference the graphicLayer.graphics[0] the system is telling me that it is undefined. If I have 3 graphics why would it be undefined?

[KenBuja]

Can you post the code showing how you define graphicsLayer and add the graphics to it?

[RobertScheitlin__GISP · Accepted solution]

David,

   In the 4.x API the graphics property return a Collection not a flat array like the 3.x API did. SO you have to use collection methods.

//Old way in 3.x
graphicLayer.graphics[0];

//New way in 4.x
graphicLayer.graphics.getItemAt(0);‍‍‍‍‍

[DavidKucharski]

The graphicLayer.graphics.getItemAt(0) works to get the graphic. Thank you. One last issue though. I am creating the graphic and adding it to the layer using the below code in bold. At the end I add 'id' as an attribute to uniquely identify it. 

In another process, directly below, I loop through the graphic layer looking for a graphic with an 'id' value. I am getting errors when trying to access the attributes section. 

for (gL = 0; highlightGeographyLyr.graphics.length; gL++) {
   if (highlightGeographyLyr.graphics.getItemAt(gl).attributes[0] == geography) {
            highlightGeographyLyr.remove(highlightGeographyLyr.graphics.getItemAt(gl));
}
}

function highLightGeography(response) {

// Loop through each of the results and assign a symbol and PopupTemplate
// to each so they may be visualized on the map
var geography = "";
var peakResults = arrayUtils.map(response.features, function (
feature) {

geography = feature.attributes.ID_;
// Sets the symbol of each resulting feature to a cone with a
// fixed color and width. The height is based on the mountain's elevation
feature.symbol = {
type: "simple-fill", // autocasts as new PointSymbol3D()
color: {
r: 245,
g: 245,
b: 245,
a: 0.5
},
style: "solid",
opacity: 0.2,
outline: { color: "white", width: 1 }
};

return feature;
});

peakResults.attributes = { "id": geography };
highlightGeographyLyr.addMany(peakResults);
}

[RobertScheitlin__GISP]

David,

  Would it not be length - 1 in your for loop?

for (gL = 0; highlightGeographyLyr.graphics.length - 1; gL++) {‍

[DavidKucharski]

For 1 graphic in the layer, the below lines error and say it is undefined. 

highlightGeographyLyr.graphics.getItemAt(0).attributes[0]

highlightGeographyLyr.graphics.getItemAt(0).attributes(0)

highlightGeographyLyr.graphics.getItemAt(0).attributes.id

[RobertScheitlin__GISP]

David,

  Strange a Collection is a zero based index and the attributes are an Object so your first line should work.

[DavidKucharski]

I am actually comparing it in a for loop to the 'geography' which is a variable. The javascript blows up on the compare. In the immediate window, I try to see what the value is

? highlightGeographyLyr.graphics.getItemAt(gl).attributes[0] 

It gives me a value of {...} in the immediate window so something seems to be there.

for (gL = 0; highlightGeographyLyr.graphics.length - 1; gL++) {
    if (highlightGeographyLyr.graphics.getItemAt(gl).attributes[0] == geography) {
                    highlightGeographyLyr.remove(highlightGeographyLyr.graphics.getItemAt(gl));
    }
}

[RobertScheitlin__GISP]

David,

  So you specify gL as your interator index and then you use gl (all lower case) this is an issue in JavaScript as it is case sensitive

[DavidKucharski]

Thank you and sorry about the javascript error. It is working now.