Query a feature layer (spatial)

Learn how to execute a spatial query to access polygon features from a feature service.

A feature layer can contain a large number of features stored in ArcGIS. To access a subset of these features, you can execute an SQL or spatial query, either together or individually. The results can contain the attributes, geometry, or both for each record. SQL and spatial queries are useful when a feature layer is very large and you want to access only a subset of its data.

In this tutorial, you use GL Draw to sketch a feature on the map, and then use ArcGIS REST JS to perform a spatial query against the LA County Parcels hosted feature layer. The layer contains ±2.4 million features. The spatial query returns all of the parcels that intersect the sketched feature. A pop-up is also used to display feature attributes.

Prerequisites

You need an ArcGIS Location Platform or ArcGIS Online account.

Steps

Create a new pen

To get started, you can complete the Display a map tutorial or use the .

Get an access token

You need an access token with the correct privileges to access the resources used in this tutorial.

Go to the Create an API key tutorial and create an API key with the following privilege(s):
- Privileges
  - Location services > Basemaps
- Item access
  - Note: If you are using your own custom data layer for this tutorial, you need to grant the API key credentials access to the layer item. Learn more in Item access privileges.
Copy the API key access token to your clipboard when prompted.

In CodePen, update the accessToken variable to use your access token.

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const accessToken = "YOUR_ACCESS_TOKEN";
const basemapEnum = "arcgis/outdoor";
const map = new maplibregl.Map({
  container: "map", // the id of the div element
  style: `https://basemapstyles-api.arcgis.com/arcgis/rest/services/styles/v2/styles/${basemapEnum}?token=${accessToken}`,
  zoom: 12, // starting zoom
  center: [-118.805, 34.027] // starting location [longitude, latitude]
});

Run the code to ensure the basemap is displayed in the map.

To learn about the other types of authentication available, go to Types of authentication.

Add script references

This tutorial uses three sets of libraries. ArcGIS REST JS is used for querying the feature layer. Mapbox GL Draw provides drawing tools, allowing the user to define a point, line, or polygon of interest. Terraformer is used to convert GeoJSON features generated by Mapbox GL Draw into ArcGIS JSON geometries; a requirement to query the feature layer service.

Add <script> tags to reference the libraries.

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  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" />
    <script src=https://unpkg.com/maplibre-gl@4/dist/maplibre-gl.js></script>
    <link href=https://unpkg.com/maplibre-gl@4/dist/maplibre-gl.css rel="stylesheet" />

    <link rel="stylesheet" href="https://api.mapbox.com/mapbox-gl-js/plugins/mapbox-gl-draw/v1.4.2/mapbox-gl-draw.css" type="text/css" />
    <script src="https://api.mapbox.com/mapbox-gl-js/plugins/mapbox-gl-draw/v1.4.2/mapbox-gl-draw.js"></script>

    <script src="https://unpkg.com/@esri/arcgis-rest-request@4/dist/bundled/request.umd.js"></script>
    <script src="https://unpkg.com/@esri/arcgis-rest-feature-service@4/dist/bundled/feature-service.umd.js"></script>

    <script src="https://unpkg.com/@terraformer/arcgis@2.1.2/dist/t-arcgis.umd.js"></script>

    <style>
      html,
      body,
      #map {
        padding: 0;
        margin: 0;
        height: 100%;
        width: 100%;
        font-family: Arial, Helvetica, sans-serif;
        font-size: 14px;
        color: #323232;
      }
    </style>
  </head>
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Add Mapbox GL Draw

To display the Mapbox GL Draw controls, create a MapboxDraw and call map.addControl. By default, other tools are included, so you need to specify the three required tools: point, line, and polygon.

Create a MapboxDraw and add it to the Map.

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      const map = new maplibregl.Map({
        container: "map", // the id of the div element
        style: `https://basemapstyles-api.arcgis.com/arcgis/rest/services/styles/v2/styles/${basemapEnum}?token=${accessToken}`,
        zoom: 12, // starting zoom

        center: [-118.80543, 34.03] // starting location [longitude, latitude]

      });

      const draw = new MapboxDraw({
        displayControlsDefault: false, // Don't add any tools other than those below
        controls: {
          point: true,
          line_string: true,
          polygon: true
        }
      });
      map.addControl(draw, "top-left");
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Edit the MapboxDraw global constants to allow compatibility with MapLibre GL JS.

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      const map = new maplibregl.Map({
        container: "map", // the id of the div element
        style: `https://basemapstyles-api.arcgis.com/arcgis/rest/services/styles/v2/styles/${basemapEnum}?token=${accessToken}`,
        zoom: 12, // starting zoom

        center: [-118.80543, 34.03] // starting location [longitude, latitude]

      });

      MapboxDraw.constants.classes.CONTROL_BASE = "maplibregl-ctrl";
      MapboxDraw.constants.classes.CONTROL_PREFIX = "maplibregl-ctrl-";
      MapboxDraw.constants.classes.CONTROL_GROUP = "maplibregl-ctrl-group";

      const draw = new MapboxDraw({
        displayControlsDefault: false, // Don't add any tools other than those below
        controls: {
          point: true,
          line_string: true,
          polygon: true
        }
      });
      map.addControl(draw, "top-left");
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Add query layers

Three layers are required to display the three types of query you can perform: circle, line, and fill. They share a single GeoJSON source, which at any time will contain one feature of either Point, LineString or Polygon geometry. Create the source with an empty GeoJSON feature collection.

A line layer can display both line features and the border of polygon features.

The circle layer should be filtered to only display point features. Otherwise, a circle will be shown at each vertex of line and polygon features. You can use a filter and the ['geometry-type'] expression. See the MapLibre Style Specification for more details.

Similarly, the fill layer should be filtered to only display polygon features. Otherwise, line features will be treated as polygons and filled inappropriately.

Create an addQueryLayers function. Inside, add a GeoJSON source and circle, line, and fill layers

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      function addQueryLayers() {
        map.addSource("query", {
          type: "geojson",
          data: {
            type: "FeatureCollection",
            features: []
          }
        });
        map.addLayer({
          id: "query-line",
          type: "line",
          source: "query",
          paint: {
            "line-color": "hsl(140, 0%, 30%)",
            "line-width": 2,
            "line-dasharray": [2, 2]
          }
        });
        map.addLayer({
          id: "query-fill",
          type: "fill",
          source: "query",
          paint: {
            "fill-color": "hsl(140, 0%, 50%)",
            "fill-opacity": 0.2
          },
          filter: ["==", ["geometry-type"], "Polygon"]
        });

        map.addLayer({
          id: "query-circle",
          type: "circle",
          source: "query",
          paint: {
            "circle-color": "hsl(140, 0%, 30%)"
          },
          filter: ["==", ["geometry-type"], "Point"]
        });
      }
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Add parcel layers

Parcels returned by the query are simple polygons. You can display them with a GeoJSON source and a fill layer.

Create an addParcelLayers function. Inside, add a GeoJSON source and a fill layer.

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        map.addLayer({
          id: "query-circle",
          type: "circle",
          source: "query",
          paint: {
            "circle-color": "hsl(140, 0%, 30%)"
          },
          filter: ["==", ["geometry-type"], "Point"]
        });
      }

      function addParcelLayers() {
        map.addSource("parcels", {
          type: "geojson",
          data: {
            type: "FeatureCollection",
            features: []
          },

        });
        map.addLayer({
          id: "parcels-fill",
          source: "parcels",
          type: "fill",

          paint: {
            "fill-color": "hsl(200, 80%, 50%)",
            "fill-opacity": 0.5,
            "fill-outline-color": "white"
          }
        });
      }
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Add the data attribution for the feature layer source.

Go to the LA County Parcels item.
Scroll down to the Credits (Attribution) section and copy its value.

Create an attribution property and paste the attribution value from the item.

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      function addParcelLayers() {
        map.addSource("parcels", {
          type: "geojson",
          data: {
            type: "FeatureCollection",
            features: []
          },

          // Attribution text retrieved from https://arcgis-devlabs.maps.arcgis.com/home/item.html?id=a6fdf2ee0e454393a53ba32b9838b303
          attribution: "LA County Parcels"

        });
        map.addLayer({
          id: "parcels-fill",
          source: "parcels",
          type: "fill",

          paint: {
            "fill-color": "hsl(200, 80%, 50%)",
            "fill-opacity": 0.5,
            "fill-outline-color": "white"
          }
        });
      }
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Add a load handler

To add layers to the map, use the load event to ensure the map is fully loaded.

Add an event handler for the load event. Inside, call addQueryLayers and addParcelLayers;

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          paint: {
            "fill-color": "hsl(200, 80%, 50%)",
            "fill-opacity": 0.5,
            "fill-outline-color": "white"
          }
        });
      }

      map.on("load", () => {

        addParcelLayers();

        addQueryLayers();
      });
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Get the draw feature

Mapbox GL Draw emits a draw.create event when you have finished drawing a feature. You can listen to this event to respond to the newly created feature.

By default, Mapbox GL Draw keeps all previously drawn features visible in its own layer. To prevent this, use deleteAll after copying the feature.

Add an event handler for draw.create. Inside, store the feature in the query layer, then delete all features from Mapbox GL Draw.

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      map.on("load", () => {

        addParcelLayers();

        addQueryLayers();
      });

      map.on("draw.create", (e) => {
        const feature = e.features[0];
        map.getSource("query").setData(feature);
        draw.deleteAll();

      });
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Click Run at the top right to test your code. You should be able to sketch a point, line or polygon feature, and see it turn into a green feature when complete.

Execute the query

Use the ArcGIS REST JS queryFeatures method to find features in the LA County Parcels feature layer that intersect the sketched feature. Use Terraformer.geojsonToArcGIS to convert the GeoJSON from Mapbox GL Draw into the ArcGIS geometry format.

When the matching parcels are returned, you can call setData on the parcels source to display them.

Create a function called executeQuery with geometry and geometryType parameters. Inside, create a new arcgisRest.ApiKeyManager to access the feature service. Call arcgisRest.queryFeatures. Pass the geometry and geometryType. Specify GeoJSON as the return type, requesting returnGeometry and specific outFields. All of the features within the geometry will be returned with attribute information set by the outFields property.

There are many other spatial relationships that you can specify with spatialRel. For example, you can use esriSpatialRelContains to only return parcels within the sketched polygon. See the ArcGIS services reference for details.

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      map.on("draw.create", (e) => {
        const feature = e.features[0];
        map.getSource("query").setData(feature);
        draw.deleteAll();

      });

      function executeQuery(geometry, geometryType) {

        arcgisRest
          .queryFeatures({
            url: "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/LA_County_Parcels/FeatureServer/0",
            geometry: geometry,
            geometryType: geometryType,
            spatialRel: "esriSpatialRelIntersects",
            f: "geojson",
            returnGeometry: true,
            outFields: ["APN", "UseType", "TaxRateCity", " Roll_LandValue"]
          })

      }
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Add a response handler. Inside, set the returned parcels as the data for the parcels source.

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        arcgisRest
          .queryFeatures({
            url: "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/LA_County_Parcels/FeatureServer/0",
            geometry: geometry,
            geometryType: geometryType,
            spatialRel: "esriSpatialRelIntersects",
            f: "geojson",
            returnGeometry: true,
            outFields: ["APN", "UseType", "TaxRateCity", " Roll_LandValue"]
          })

          .then((response) => {
            map.getSource("parcels").setData(response);
          });

      }
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In your MapboxDraw event handler, call executeQuery. Use Terraformer.geojsonToArcGIS to convert geometry into an ArcGIS JSON format.

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      map.on("draw.create", (e) => {
        const feature = e.features[0];
        map.getSource("query").setData(feature);
        draw.deleteAll();

        const geometry = Terraformer.geojsonToArcGIS(feature.geometry);
        let geometryType = "esriGeometry" + feature.geometry.type;
        if (feature.geometry.type === "LineString") {
          geometryType = "esriGeometryPolyline";
        }
        executeQuery(geometry, geometryType);

      });
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At the top right, click Run. When you create a feature using the toolbox, a spatial query will run against the feature layer and display all land parcels within the boundary of the feature.

Add a pop-up

You can add a pop-up to view attributes of a parcel when you click on it.

Add a click event handler to the parcels-fill layer. Inside, construct the pop-up content from the attributes of the clicked parcel.

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          .then((response) => {
            map.getSource("parcels").setData(response);
          });

      }

      map.on("click", "parcels-fill", (e) => {
        const p = e.features[0].properties;
        const message =
          `<b>Parcel ${p.APN}</b>` +
          `Type: ${p.UseType} <br>` +
          `Land value: $${p.Roll_LandValue.toLocaleString()} <br>` +
          `Tax Rate City: ${p.TaxRateCity}`;

      });
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Create a Popup. Use Popup.setHTML to set the content. Update the position of the pop-up using Popup.setLngLat, and add it to the map using Popup.addTo.

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      map.on("click", "parcels-fill", (e) => {
        const p = e.features[0].properties;
        const message =
          `<b>Parcel ${p.APN}</b>` +
          `Type: ${p.UseType} <br>` +
          `Land value: $${p.Roll_LandValue.toLocaleString()} <br>` +
          `Tax Rate City: ${p.TaxRateCity}`;

        new maplibregl.Popup().setHTML(message).setLngLat(e.lngLat).addTo(map);

      });
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Run the app

In CodePen, run your code to display the map.

When you click on the map to draw a polygon, a spatial query will run against the feature layer and display all land parcels that intersect the boundary of the feature. You can click on a parcel to see a pop-up with information about the parcel, or click somewhere else to reset the map.

What's next?

Learn how to use additional ArcGIS location services in these tutorials:

Query a feature layer (SQL)

Execute a SQL query to access polygon features from a feature layer.

Get global data

Query demographic information for locations around the world with the GeoEnrichment service.

Get local data

Query regional facts, spending trends, and psychographics with the GeoEnrichment service.

Add a feature layer

Add features from feature layers to a map.

Style a feature layer

Use data-driven styling to apply symbol colors and styles to feature layers.