Labeling of decimals, rounding/padding using LabelLayer

[ZoeZaloudek]

I have a web map with a FeatureLayer (polygons).  I’m using a LabelLayer to label the polygons with a double-type field.  My values in the field go to the hundredth, but some don’t. (example image below)  I want to show all labels with values to the tenth, which means some will have to be rounded, and others will have to be padded on the right with “.0”

I know how to do this in ArcMap - go to the layer’s attribute table, go to the field’s numeric properties, set how many decimal places to show, also check the ‘Pad with zeros’ box. How do I accomplish this with my web map? I can’t find a decimal places setting in the documentation for LabelLayer...   Is there a round/pad function I can use in the textExpression of the addFeatureLayer method?  Or is there a way to set field display properties in the map service?

[TyroneBiggums]

You can round up to the nearest tenth programmatically with Math.ceil10(yourValue, -1) if that helps. But, since the data is coming from a FeatureLayer that might not work out very well. Maybe this will at least steer you in the right direction.

[TracySchloss]

Have you looked at this section: Format info window content | Guide | ArcGIS API for JavaScript

I wonder if any of the techniques you can use for formatting infoWindows would work on a labelLayer?

[KellyHutchins · Accepted solution]

Zoe Zaloudek​ You can do this using the LabelLayer class by specifying the number of places. Here's a jsbin that shows how to do this:

JS Bin - Collaborative JavaScript Debugging

And here's the relevant bit of code:

      // Setup label properties

      var statesLabels = new LabelClass({

        labelExpressionInfo: {"value": "{AVE_FAM_SZ}"},

        fieldInfos:[{

          "fieldName": "AVE_FAM_SZ",

          "format": {"places":2}

        }]

      });

      // Apply label info to the feature layer

      states.setLabelingInfo([statesLabels]);

[ZoeZaloudek]

Well, I got LabelClass to work, so I've partially succeeded.  However, setting the fieldInfos>format>places doesn't seem to be doing the trick for me.  Here's the code I implemented.  The variables flayer, field and labelCDvSymbol are defined earlier in my code.

var labelsCDs = new LabelClass({labelExpressionInfo: {"value": "{"+field+"}"}, minScale: 10000000});
labelsCDs.fieldInfos = [{"fieldName": field, "format": {"places": 1}}]; 
labelsCDs.symbol = labelCDvSymbol;
console.log(labelsCDs);
fLayer.setLabelingInfo([labelsCDs]);

The labels show the correct field and font/symbol, but they're still just not rounded/padded to the tenth.  I can see in the console that the fieldInfos>format>places has been set to 1.

[KenBuja]

Put that into the constructor of the LabelClass

var labelsCDs = new LabelClass({
    labelExpressionInfo: {"value": "{"+field+"}"}, 
    minScale: 10000000,
    fieldInfos: [{"fieldName": field, "format": {"places": 1}}],
    symbol: labelCDvSymbol
});  
console.log(labelsCDs);  
fLayer.setLabelingInfo([labelsCDs]); 

You cannot set the properties of a class after it's been created. You have to use methods (which aren't available for this class).

[ZoeZaloudek]

Hm, I edited my code to match, but that still didn't do it.  The label symbol looks different though.

It must be something else in my code that's messing it up.  There's a lot more going on in addition to the label changes - changing symbology, text, etc.  I figured out how to share on JS Bin (which I didn't even know about until I saw the examples that Kelly Hutchins posted-thanks!) and put the whole thing here:

JS Bin - Collaborative JavaScript Debugging

[KenBuja]

The problem was the version of the API. It works in v3.14, but not 3.13.

[ZoeZaloudek]

Aha!  That was it!  The labels round/pad correctly now.  Thanks for digging into this with me!

[TracySchloss]

Does this work for FeatureLayers?  The documentation specifically says ArcGISDynamicMapServiceLayer.