Reverse geocode | OpenLayers

Learn how to find an address near a location.

Reverse geocode coordinates to addresses with the Geocoding service using API key authentication

Reverse geocoding is the process of converting a location to an address or place. To reverse geocode, you use the ArcGIS Geocoding service and the reverseGeocode operation. This operation requires an initial location and returns an address with attributes such as place name and location.

In this tutorial, you use the reverseGeocode method of ArcGIS REST JS to reverse geocode and find the closest address to your clicked location on the map.

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
  - Location services > Geocoding

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.

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    /* Use for API key authentication */
    const accessToken = "YOUR_ACCESS_TOKEN";
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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
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    /* 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
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    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

This tutorial uses ArcGIS REST JS for reverse geocoding, and the ol-popup library to display pop-ups.

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

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    <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/@esri/arcgis-rest-geocoding@4/dist/bundled/geocoding.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">
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Update the map

An arcgis/navigation basemap style is typically used in geocoding and routing applications. Update the basemap layer to use the style.

Update the basemap and the map initialization to center on location [2.3522,48.8566], Paris.

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    <script>

    /* Use for API key authentication */
    const accessToken = "YOUR_ACCESS_TOKEN";

    // or

    /* Use for user authentication */
    // const session = await arcgisRest.ArcGISIdentityManager.beginOAuth2({
    //   clientId: "YOUR_CLIENT_ID", // Your client ID from OAuth credentials
    //   redirectUri: "YOUR_REDIRECT_URI", // The redirect URL registered in your OAuth credentials
    //   portal: "YOUR_PORTAL_URL" // Your portal URL
    // })

    // const accessToken = session.token;

    const map = new ol.Map({
      target: "map"
    });

    const view = new ol.View({

      center: ol.proj.fromLonLat([2.3522, 48.8566]), // Paris

      zoom: 12
    });
    map.setView(view);

    const basemapId = "arcgis/navigation";

    olms.apply(map, `https://basemapstyles-api.arcgis.com/arcgis/rest/services/styles/v2/styles/${basemapId}?token=${accessToken}`).then(() => {

      // Add Esri attribution
      // Learn more in https://esriurl.com/attribution
      const source = map.getLayers().item(0).getSource();
      const poweredByEsriString = "Powered by <a href='https://www.esri.com/en-us/home' target='_blank'>Esri</a> | ";

      const attributionFn = source.getAttributions();
      if (attributionFn) {
        source.setAttributions((ViewStateLayerStateExtent) => {
          return [poweredByEsriString, ...attributionFn(ViewStateLayerStateExtent)];
        });
      } else source.setAttributions(poweredByEsriString);

    });

    </script>
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Add a pop-up

Create a Popup to display the results of the reverse geocode. It is a type of Overlay so you add it to the map with map.addOverlay.

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

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    const view = new ol.View({

      center: ol.proj.fromLonLat([2.3522, 48.8566]), // Paris

      zoom: 12
    });
    map.setView(view);

    const popup = new Popup();
    map.addOverlay(popup);
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Add click event handler

Before you call the reverse Geocoding service, you need the location of the clicked point. Use ol.proj.transform to convert this into a latitude and longitude.

Add a click handler to the map. Inside, convert the clicked coordinates from the event object into latitude and longitude.

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    const popup = new Popup();
    map.addOverlay(popup);

    map.on("click", (e) => {

      const coords = ol.proj.transform(e.coordinate, "EPSG:3857", "EPSG:4326");

    });
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Call reverse geocode service

Use the ArcGIS REST JS reverseGeocode method to find an address closest to a point.

Inside the click handler, create a new arcgisRest.ApiKeyManager to access the Geocoding service. Call the arcgisRest.reverseGeocode method with the coordinates array.

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      const coords = ol.proj.transform(e.coordinate, "EPSG:3857", "EPSG:4326");

      const authentication = arcgisRest.ApiKeyManager.fromKey(accessToken);

      arcgisRest
        .reverseGeocode(coords, {
          authentication
        })
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Display the result

The response from the reverseGeocode operation contains two properties. address is a structured object with fields such as street name and business name. location contains the location of the returned address, which may differ from the coordinates you provided. Display these values in a pop-up. Use a catch handler to check for errors accessing the service.

Add a then handler. Use popup.show to display the resulting address and coordinates.

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      arcgisRest
        .reverseGeocode(coords, {
          authentication
        })

        .then((result) => {
          const message =
            `${result.address.LongLabel}<br>` + `${result.location.x.toLocaleString()}, ${result.location.y.toLocaleString()}`;

          popup.show(e.coordinate, message);
        })
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Add a catch handler. In most cases, errors occur when the user clicks in the water, so simply hide the pop-up when this happens. Use popup.hide() to remove the pop-up and then write the error to the console.

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          popup.show(e.coordinate, message);
        })

        .catch((error) => {
          popup.hide();
          console.error(error);
        });
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Run the app

Run the app.

Click on the map to reverse geocode the clicked point and display a pop-up with the closest address and coordinates.

What's next?

Learn how to use additional location services in these tutorials:

Search with autosuggest

Search for addresses with partial text using autosuggest.

Find place addresses

Search for places by category near a location.

Find a route and directions

Find a route and directions from a start and finish location.