How to style (color) a polygon based on a field value in a feature layer

Ef — Mon, 11 Nov 2024 15:43:10 GMT

I have a method to create a feature layer. it consists of polygons. Each represent a unit. these units have a field of unit_type. Based on the type I would the polygon to have a different color.
I created a renderer to handle the logic

my_renderer = {
    "type": "uniqueValue",
    "field1": "unit_type",
    "uniqueValueInfos": [
        {
            "value": "YES_WORK",
            "symbol": {
                "type": "esriSFS",
                "style": "esriSFSSolid",
                "color": [0, 0, 255, 128],  # Blue
                "outline": {
                    "type": "esriSLS",
                    "style": "esriSLSSolid",
                    "color": [255, 255, 255, 255],
                    "width": 1
                }
            },
            "label": "Yes Work"
        },
        {
            "value": "NO_WORK",
            "symbol": {
                "type": "esriSFS",
                "style": "esriSFSSolid",
                "color": [255, 0, 0, 128],  # Red
                "outline": {
                    "type": "esriSLS",
                    "style": "esriSLSSolid",
                    "color": [255, 255, 255, 255],
                    "width": 1
                }
            },
            "label": "NO_WORK"
        }
    ],
    "defaultSymbol": {
        "type": "esriSFS",
        "style": "esriSFSSolid",
        "color": [0, 0, 255, 128],  # Default color (Blue)
        "outline": {
            "type": "esriSLS",
            "style": "esriSLSSolid",
            "color": [255, 255, 255, 255],
            "width": 1
        }
    },
    "defaultLabel": "Default"
}

and to pass it here to create the layer

operational_layers.append(
    {
        "url": f"{FEATURE_LAYER_URL}/0",
        "type": "FeatureLayer",
        "title": "ProjectBoundaries",
        "token": SOME_TOKEN,
        "opacity": 0.4,
        "minScale": 0,
        "maxScale": 0,
        "renderer": my_renderer  # Ensure the renderer is included here
    }
)

export_map_task_payload = {
    "operationalLayers": operational_layers,
    "mapOptions": {
        "extent": extent,
        "spatialReference": {
            "latestWkid": 3857,
            "wkid": 102100
        },
        "showAttribution": True,
    },
    "exportOptions": {
        "outputSize": [800, 800]
    }
}

but it doesn't work. What is wrong. and if this is not not the way how to achieve the requirement

Re: How to style (color) a polygon based on a field value in a feature layer

Clubdebambos — Mon, 10 Mar 2025 16:11:45 GMT

Hi @Ef,

It seems you are quite close here. From the information provided it looks like you are trying to add a Layer to a WebMap (operationalLayers) and set the symbology (renderer).

Check the commented code below for the workflow.

from arcgis.gis import GIS ## access ArcGIS Online agol = GIS("home") ## get the WebMap Item as an Item object wm_item = agol.content.get("WM_ITEM_ID") ## get the WebMap Definition wm_def = wm_item.get_data() ## get the current opetaionalLayers as a list ol = wm_def["operationalLayers"] ## create the renderer definition my_renderer = {...} ## create the new layer definition with the renderer ## notice the path to the renderer in the layerDefinition property new_lyr_def = { "url": f"{FEATURE_LAYER_URL}/0", "type": "FeatureLayer", "title": "ProjectBoundaries", "token": SOME_TOKEN, "opacity": 0.4, "minScale": 0, "maxScale": 0, "layerDefinition": { "drawingInfo" : { "renderer" : my_renderer } } } ## append the new layer to the ol list ol.append(new_lyr_def) ## test print to make sure the layer has been added print(ol) ## if not adding try the below #ol = ol + [new_lyr_def] ## assign the new ol to the WebMap OL Definition wm_def["operationalLayers"] = ol ## create a dictionary to hold the new update info update_properties = {"text" : wm_def} ## apply the update to the WebMap Item object wm_itm.update( "item_properties" : update_properties )

All the best,

Glen

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How to style (color) a polygon based on a field value in a feature layer

Re: How to style (color) a polygon based on a field value in a feature layer