Add a feature layer as GeoJSON | OpenLayers

Learn how to add features from feature layers to a map.

Add a feature layer as GeoJSON using API key authentication

A feature layer is a dataset in a hosted feature service. Each feature layer contains features with a single geometry type (point, line, or polygon), and a set of attributes. You can access and display features by making query requests to the feature service and displaying them in a map.

In this tutorial, you access and display three different hosted feature layers. The data is accessed and displayed as GeoJSON.

The feature layers are:

Prerequisites

You need an ArcGIS Location Platform or ArcGIS Online account.

Steps

Get the starter app

Select a type of authentication and follow the steps to create a new app.

Choose API key authentication if you:

Want the easiest way to get started.
Want to build public applications that access ArcGIS Location Services and secure items.
Have an ArcGIS Location Platform or ArcGIS Online account.

Choose user authentication if you:

Want to build private applications.
Require application users to sign in with their own ArcGIS account and access resources their behalf.
Have an ArcGIS Online account.

To learn more about both types of authentication, go to Authentication.

You can choose one of the following to create a new CodePen:

Option 1: Complete the Display a map tutorial; or,
Option 2: Start from the Display a map tutorial .

Set up authentication

Create a new API key credential with the correct privileges to get an access token.

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.

Set developer credentials

Use the API key or OAuth developer credentials so your application can access ArcGIS services.

Update the accessToken variable to use your API key.

Expand
Use dark colors for code blocks
 /* Use for API key authentication */  const accessToken = "YOUR_ACCESS_TOKEN"; 
Expand

In both the index.html and callback.html files, replace YOUR_CLIENT_ID and YOUR_REDIRECT_URL with the client ID and redirect URL of your OAuth credentials.

index.html
Use dark colors for code blocks
 /* Use for user authentication */  const clientId = "YOUR_CLIENT_ID"; // Your client ID from OAuth credentials  const redirectUri = ""YOUR_REDIRECT_URI""; // The redirect URL registered in your OAuth credentials  const session = await arcgisRest.ArcGISIdentityManager.beginOAuth2({  clientId,  redirectUri,  portal: "https://www.arcgis.com/sharing/rest" // Your portal URL  });   const accessToken = session.token; 

callback.html
Use dark colors for code blocks
 arcgisRest.ArcGISIdentityManager.completeOAuth2({  clientId: "YOUR_CLIENT_ID", // Your client ID from OAuth credentials  redirectUri: "YOUR_REDIRECT_URI", // The redirect URL registered in your OAuth credentials  portal: "https://www.arcgis.com/sharing/rest" // Your portal URL  }); 

Run the app and ensure you can sign in successfully.

If you are unable to sign in, make sure you have the correct redirect URL and port. This URL varies based on your application and typically takes the format of https://<server>[:port]/callback.html or http://my-arcgis-app:/auth. For example, if you are running an application on http://127.0.0.1:5500/, set http://127.0.0.1:5500/callback.html as your redirect URL in the index.html and callback.html file and your developer credential. They all have to match!

Add references to ArcGIS REST JS

This tutorial uses ArcGIS REST JS for accessing the feature service. It also uses the ol-popup library to display pop-ups.

In the <head> element, add references to the ArcGIS REST JS and ol-popup libraries.

Expand
Use dark colors for code blocks
 <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@v10.7.0/ol.css">  <script src="https://cdn.jsdelivr.net/npm/ol@v10.7.0/dist/ol.js"></script>   <script src="https://cdn.jsdelivr.net/npm/ol-mapbox-style@13.1.1/dist/olms.js"></script>   <script src="https://unpkg.com/@esri/arcgis-rest-request@4/dist/bundled/request.umd.js"></script>  <script src="https://unpkg.com/ol-popup@5.1.1/dist/ol-popup.js"></script>  <link rel="stylesheet" href="https://unpkg.com/ol-popup@5.1.1/src/ol-popup.css"> 
Expand

Add a point feature layer

The trailheads feature layer contains feature with a point geometry. Use a Vector layer to access the feature layer by URL and display the points. By default, they will display as white circles with blue outlines.

Create a VectorSource. Pass a new GeoJSON as the format parameter. For the url parameter, pass a direct link to a FeatureServer endpoint.

The URL contains an f=geojson parameter to request data in GeoJSON format. For more information about querying a Feature Service, see the Query a feature layer (SQL) and Query a feature layer (spatial) tutorials.

Expand
Use dark colors for code blocks
 const basemapId = "arcgis/streets";  const basemapURL = `https://basemapstyles-api.arcgis.com/arcgis/rest/services/styles/v2/styles/${basemapId}?token=${accessToken}`;   olms.apply(map, basemapURL).then(function (map) {   const pointLayerName = "Trailheads";  const pointLayerURL =  "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +  pointLayerName +  "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";   const pointSource = new ol.source.Vector({  format: new ol.format.GeoJSON(),  url: pointLayerURL,   }); 
Expand

Add the data attribution for the feature layer source.

Go to the Trailheads (Santa Monica Mountains) item.
Scroll down to the Acknowledgments section and copy its value.

Paste the copied value to the attributions property.

Expand
Use dark colors for code blocks
 const basemapId = "arcgis/streets";  const basemapURL = `https://basemapstyles-api.arcgis.com/arcgis/rest/services/styles/v2/styles/${basemapId}?token=${accessToken}`;   olms.apply(map, basemapURL).then(function (map) {   const pointLayerName = "Trailheads";  const pointLayerURL =  "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +  pointLayerName +  "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";   const pointSource = new ol.source.Vector({  format: new ol.format.GeoJSON(),  url: pointLayerURL,   // Attribution text retrieved from https://arcgis.com/home/item.html?id=883cedb8c9fe4524b64d47666ed234a7  attributions: ["Los Angeles GeoHub |"]   }); 
Expand

Create a Vector layer using the Vector source you defined.

Expand
Use dark colors for code blocks
 const pointSource = new ol.source.Vector({  format: new ol.format.GeoJSON(),  url: pointLayerURL,   // Attribution text retrieved from https://arcgis.com/home/item.html?id=883cedb8c9fe4524b64d47666ed234a7  attributions: ["Los Angeles GeoHub |"]   });   const pointLayer = new ol.layer.Vector({  source: pointSource  }); 
Expand

Add a line feature layer

The Trails feature layer contains features with a line geometry. Use a Vector layer to access the feature layer by URL and display the lines. By default, the features are displayed as blue lines.

Create a VectorSource with format and url parameters.

Expand
Use dark colors for code blocks
 const pointLayer = new ol.layer.Vector({  source: pointSource  });   const lineLayerName = "Trails";  const lineLayerURL =  "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +  lineLayerName +  "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";   const lineSource = new ol.source.Vector({  format: new ol.format.GeoJSON(),  url: lineLayerURL,   }); 
Expand

Add the data attribution for the feature layer source.

Go to the Trails item.
Scroll down to the Acknowledgments section and copy its value.

Paste the copied value to the attributions property.

Expand
Use dark colors for code blocks
 const pointLayer = new ol.layer.Vector({  source: pointSource  });   const lineLayerName = "Trails";  const lineLayerURL =  "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +  lineLayerName +  "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";   const lineSource = new ol.source.Vector({  format: new ol.format.GeoJSON(),  url: lineLayerURL,   // Attribution text retrieved from https://arcgis.com/home/item.html?id=69e12682738e467eb509d8b54dc73cbd  attributions: ["Los Angeles GeoHub |"]   }); 
Expand

Create a Vector layer using the Vector source you defined.

Expand
Use dark colors for code blocks
 const lineSource = new ol.source.Vector({  format: new ol.format.GeoJSON(),  url: lineLayerURL,   // Attribution text retrieved from https://arcgis.com/home/item.html?id=69e12682738e467eb509d8b54dc73cbd  attributions: ["Los Angeles GeoHub |"]   });   const lineLayer = new ol.layer.Vector({  source: lineSource  }); 
Expand

Add a polygon feature layer

The Parks and Open Space feature layer contains features with a polygon geometry. Use a Vector layer to access the feature layer by URL and display the polygons. By default, polygon features are displayed as translucent white fill with blue outlines.

Create a VectorSource with format and url parameters.

Expand
Use dark colors for code blocks
 const lineLayer = new ol.layer.Vector({  source: lineSource  });   const polygonLayerName = "Parks_and_Open_Space";  const polygonLayerURL =  "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +  polygonLayerName +  "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";   const polygonSource = new ol.source.Vector({  format: new ol.format.GeoJSON(),  url: polygonLayerURL,   }); 
Expand

Add the data attribution for the feature layer source.

Go to the Parks and Open Space item.
Scroll down to the Acknowledgments section and copy its value.

Paste the copied value to the attributions property.

Expand
Use dark colors for code blocks
 const lineLayer = new ol.layer.Vector({  source: lineSource  });   const polygonLayerName = "Parks_and_Open_Space";  const polygonLayerURL =  "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +  polygonLayerName +  "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";   const polygonSource = new ol.source.Vector({  format: new ol.format.GeoJSON(),  url: polygonLayerURL,   // Attribution text retrieved from https://arcgis.com/home/item.html?id=f2ea5d874dad427294641d2d45097c0e  attributions: ["Los Angeles GeoHub |"]   }); 
Expand

Create a Vector layer using the Vector source you defined.

Expand
Use dark colors for code blocks
 const polygonSource = new ol.source.Vector({  format: new ol.format.GeoJSON(),  url: polygonLayerURL,   // Attribution text retrieved from https://arcgis.com/home/item.html?id=f2ea5d874dad427294641d2d45097c0e  attributions: ["Los Angeles GeoHub |"]   });   const polygonLayer = new ol.layer.Vector({  source: polygonSource  }); 
Expand

To display multiple layers in a specific order, you group them using a LayerGroup. Add all of the layers you created to the group, then display it on the map using map.addLayer().

Expand
Use dark colors for code blocks
 const layerGroup = new ol.layer.Group({  layers: [polygonLayer, lineLayer, pointLayer]  });   map.addLayer(layerGroup); 
Expand

Add a pop-up

You can use a Popup to show data attributes for a feature when you click on them. A popup is a type of Overlay so you add it to the map with map.addOverlay. To get a feature, you use the click event and map.getFeaturesAtPixel to get the features at a click point. You also use the point to position the Popup at the correct location.

For a full list of possible attributes to show, see the feature layer pages:

Create a Popup and save it to a popup variable. Add it to the map with map.addOverlay.

Expand
Use dark colors for code blocks
 const polygonLayer = new ol.layer.Vector({  source: polygonSource  });   const layerGroup = new ol.layer.Group({  layers: [polygonLayer, lineLayer, pointLayer]  });   map.addLayer(layerGroup);   const popup = new Popup();  map.addOverlay(popup); 
Expand

Add a click event handler. Inside, check if a feature from the trailheads layer was clicked. If so, move the pop-up, and show the trailhead name and park name (TRL_NAME and PARK_NAME). Otherwise, check the trails layer; show the trail name, length and elevation gain (TRL_NAME, LENGTH_MI, ELEV_GAIN) if it was clicked. Otherwise, check the parks layer; show the park name and managing agency (PARK_NAME and MNG_AGENCY) if it was clicked. Otherwise, hide the pop-up with popup.hide;

Expand
Use dark colors for code blocks
 const popup = new Popup();  map.addOverlay(popup);   map.on("click", (event) => {  let feature = map.getFeaturesAtPixel(event.pixel, {  layerFilter: (l) => l === pointLayer  })[0];  if (feature) {  popup.show(event.coordinate, `<strong>${feature.get("TRL_NAME")}</strong><br/>${feature.get("PARK_NAME")}`);  return;  }   feature = map.getFeaturesAtPixel(event.pixel, {  layerFilter: (l) => l === lineLayer  })[0];  if (feature) {  popup.show(  event.coordinate,  `<strong>${feature.get("TRL_NAME")}</strong><br/>${feature.get("LENGTH_MI")} miles, ${feature.get("ELEV_GAIN")} feet elevation gain.`  );  return;  }   feature = map.getFeaturesAtPixel(event.pixel, {  layerFilter: (l) => l === polygonLayer  })[0];  if (feature) {  popup.show(event.coordinate, `<strong>${feature.get("PARK_NAME")}</strong><br/>${feature.get("MNG_AGENCY")}`);  return;  }  popup.hide();  }); 
Expand

Run the app

Run the app.

You should now be able to click on features to see information in a pop-up.

What's next?

Learn how to use additional location services in these tutorials: