Native ads custom events

Prerequisites

Complete the custom events setup.

Request a native ad

When the custom event line item is reached in the waterfall mediation chain, the loadNativeAd() method is called on the class name you provided when creating a custom event. In this case, that method is in SampleCustomEvent, which then calls the loadNativeAd() method in SampleNativeCustomEventLoader.

To request a native ad, create or modify a class that extends Adapter to implement loadNativeAd(). If a class that extends Adapter already exists, implement loadNativeAd() there. Additionally, create a new class to implement UnifiedNativeAdMapper.

In our custom event example, SampleCustomEvent extends the Adapter class and then delegates to SampleNativeCustomEventLoader.

package com.google.ads.mediation.sample.customevent;

import com.google.android.gms.ads.mediation.Adapter;
import com.google.android.gms.ads.mediation.MediationAdConfiguration;
import com.google.android.gms.ads.mediation.MediationAdLoadCallback;

import com.google.android.gms.ads.mediation.MediationNativeAdCallback;
...
public class SampleCustomEvent extends Adapter {
  private SampleNativeCustomEventLoader nativeLoader;

  @Override
  public void loadNativeAd(
      @NonNull MediationNativeAdConfiguration adConfiguration,
      @NonNull MediationAdLoadCallback<UnifiedNativeAdMapper, MediationNativeAdCallback> callback) {
    nativeLoader = new SampleNativeCustomEventLoader(adConfiguration, callback);
    nativeLoader.loadAd();
  }
}

SampleNativeCustomEventLoader is responsible for the following tasks:

• Loading the native ad.

• Implementing the UnifiedNativeAdMapper class.

• Receiving and reporting ad event callbacks to the Google Mobile Ads SDK.

The optional parameter defined in the AdMob UI is included in the ad configuration. The parameter can be accessed through adConfiguration.getServerParameters().getString(MediationConfiguration.CUSTOM_EVENT_SERVER_PARAMETER_FIELD). This parameter is typically an ad unit identifier that an ad network SDK requires when instantiating an ad object.

package com.google.ads.mediation.sample.customevent;

import com.google.android.gms.ads.mediation.Adapter;
import com.google.android.gms.ads.mediation.MediationNativeAdConfiguration;
import com.google.android.gms.ads.mediation.MediationAdLoadCallback;
import com.google.android.gms.ads.mediation.MediationNativeAdCallback;
...

public class SampleNativeCustomEventLoader extends SampleNativeAdListener {
  /** Configuration for requesting the native ad from the third-party network. */
  private final MediationNativeAdConfiguration mediationNativeAdConfiguration;

  /** Callback that fires on loading success or failure. */
  private final MediationAdLoadCallback<UnifiedNativeAdMapper, MediationNativeAdCallback>
      mediationAdLoadCallback;

  /** Callback for native ad events. */
  private MediationNativeAdCallback nativeAdCallback;

  /** Constructor */
  public SampleNativeCustomEventLoader(
      @NonNull MediationNativeAdConfiguration mediationNativeAdConfiguration,
      @NonNull MediationAdLoadCallback<MediationNativeAd, MediationNativeAdCallback>
              mediationAdLoadCallback) {
    this.mediationNativeAdConfiguration = mediationNativeAdConfiguration;
    this.mediationAdLoadCallback = mediationAdLoadCallback;
  }

  /** Loads the native ad from the third-party ad network. */
  public void loadAd() {
    // Create one of the Sample SDK's ad loaders to request ads.
    Log.i("NativeCustomEvent", "Begin loading native ad.");
    SampleNativeAdLoader loader =
        new SampleNativeAdLoader(mediationNativeAdConfiguration.getContext());

    // All custom events have a server parameter named "parameter" that returns
    // back the parameter entered into the UI when defining the custom event.
    String serverParameter = mediationNativeAdConfiguration
        .getServerParameters()
        .getString(MediationConfiguration
        .CUSTOM_EVENT_SERVER_PARAMETER_FIELD);
    Log.d("NativeCustomEvent", "Received server parameter.");

    loader.setAdUnit(serverParameter);

    // Create a native request to give to the SampleNativeAdLoader.
    SampleNativeAdRequest request = new SampleNativeAdRequest();
    NativeAdOptions options = mediationNativeAdConfiguration.getNativeAdOptions();
    if (options != null) {
      // If the NativeAdOptions' shouldReturnUrlsForImageAssets is true, the adapter should
      // send just the URLs for the images.
      request.setShouldDownloadImages(!options.shouldReturnUrlsForImageAssets());

      request.setShouldDownloadMultipleImages(options.shouldRequestMultipleImages());
      switch (options.getMediaAspectRatio()) {
        case NativeAdOptions.NATIVE_MEDIA_ASPECT_RATIO_LANDSCAPE:
          request.setPreferredImageOrientation(SampleNativeAdRequest.IMAGE_ORIENTATION_LANDSCAPE);
          break;
        case NativeAdOptions.NATIVE_MEDIA_ASPECT_RATIO_PORTRAIT:
          request.setPreferredImageOrientation(SampleNativeAdRequest.IMAGE_ORIENTATION_PORTRAIT);
          break;
        case NativeAdOptions.NATIVE_MEDIA_ASPECT_RATIO_SQUARE:
        case NativeAdOptions.NATIVE_MEDIA_ASPECT_RATIO_ANY:
        case NativeAdOptions.NATIVE_MEDIA_ASPECT_RATIO_UNKNOWN:
        default:
          request.setPreferredImageOrientation(SampleNativeAdRequest.IMAGE_ORIENTATION_ANY);
      }
    }

    loader.setNativeAdListener(this);

    // Begin a request.
    Log.i("NativeCustomEvent", "Start fetching native ad.");
    loader.fetchAd(request);
  }
}

Depending on whether the ad is successfully fetched or encounters an error, you would call either onSuccess() or onFailure(). onSuccess() is called by passing in an instance of the class that implements MediationNativeAd.

Typically, these methods are implemented inside callbacks from the third-party SDK your adapter implements. For this example, the Sample SDK has a SampleAdListener with relevant callbacks:

@Override
public void onNativeAdFetched(SampleNativeAd ad) {
  SampleUnifiedNativeAdMapper mapper = new SampleUnifiedNativeAdMapper(ad);
  mediationNativeAdCallback = mediationAdLoadCallback.onSuccess(mapper);
}

@Override
public void onAdFetchFailed(SampleErrorCode errorCode) {
  mediationAdLoadCallback.onFailure(SampleCustomEventError.createSampleSdkError(errorCode));
}

Map native ads

Different SDKs have their own unique formats for native ads. One might return objects that contain a "title" field, for example, while another might have "headline". Additionally, the methods used to track impressions and process clicks can vary from one SDK to another.

The UnifiedNativeAdMapper is responsible for reconciling these differences and adapting a mediated SDK's native ad object to match the interface expected by the Google Mobile Ads SDK. Custom events should extend this class to create their own mappers specific to their mediated SDK. Here's a sample ad mapper from our example custom event project:

package com.google.ads.mediation.sample.customevent;

import com.google.android.gms.ads.mediation.UnifiedNativeAdMapper;
import com.google.android.gms.ads.nativead.NativeAd;
...

public class SampleUnifiedNativeAdMapper extends UnifiedNativeAdMapper {

  private final SampleNativeAd sampleAd;

  public SampleUnifiedNativeAdMapper(SampleNativeAd ad) {
    sampleAd = ad;
    setHeadline(sampleAd.getHeadline());
    setBody(sampleAd.getBody());
    setCallToAction(sampleAd.getCallToAction());
    setStarRating(sampleAd.getStarRating());
    setStore(sampleAd.getStoreName());
    setIcon(
        new SampleNativeMappedImage(
            ad.getIcon(), ad.getIconUri(), SampleCustomEvent.SAMPLE_SDK_IMAGE_SCALE));
    setAdvertiser(ad.getAdvertiser());

    List<NativeAd.Image> imagesList = new ArrayList<NativeAd.Image>();
    imagesList.add(new SampleNativeMappedImage(ad.getImage(), ad.getImageUri(),
        SampleCustomEvent.SAMPLE_SDK_IMAGE_SCALE));
    setImages(imagesList);

    if (sampleAd.getPrice() != null) {
      NumberFormat formatter = NumberFormat.getCurrencyInstance();
      String priceString = formatter.format(sampleAd.getPrice());
      setPrice(priceString);
    }

    Bundle extras = new Bundle();
    extras.putString(SampleCustomEvent.DEGREE_OF_AWESOMENESS, ad.getDegreeOfAwesomeness());
    this.setExtras(extras);

    setOverrideClickHandling(false);
    setOverrideImpressionRecording(false);

    setAdChoicesContent(sampleAd.getInformationIcon());
  }

  @Override
  public void recordImpression() {
    sampleAd.recordImpression();
  }

  @Override
  public void handleClick(View view) {
    sampleAd.handleClick(view);
  }

  // The Sample SDK doesn't do its own impression/click tracking, instead relies on its
  // publishers calling the recordImpression and handleClick methods on its native ad object. So
  // there's no need to pass a reference to the View being used to display the native ad. If
  // your mediated network does need a reference to the view, the following method can be used
  // to provide one.

  @Override
  public void trackViews(View containerView, Map<String, View> clickableAssetViews,
      Map<String, View> nonClickableAssetViews) {
    super.trackViews(containerView, clickableAssetViews, nonClickableAssetViews);
    // If your ad network SDK does its own impression tracking, here is where you can track the
    // top level native ad view and its individual asset views.
  }

  @Override
  public void untrackView(View view) {
    super.untrackView(view);
    // Here you would remove any trackers from the View added in trackView.
  }
}

We now take a closer look at the constructor code.

Hold a reference to the mediated native ad object

The constructor accepts the SampleNativeAd parameter, the native ad class used by the Sample SDK for its native ads. The mapper needs a reference to the mediated ad so it can pass on click and impression events. SampleNativeAd is stored as a local variable.

Set mapped asset properties

The constructor uses the SampleNativeAd object to populate assets in the UnifiedNativeAdMapper.

This snippet gets the mediated ad's price data and uses it to set the mapper's price:

if (sampleAd.getPrice() != null) {
    NumberFormat formatter = NumberFormat.getCurrencyInstance();
    String priceString = formatter.format(sampleAd.getPrice());
    setPrice(priceString);
}

In this example, the mediated ad stores the price as a double, while AdMob uses a String for the same asset. The mapper is responsible for handling these types of conversions.

Map image assets

Mapping image assets is more complicated than mapping data types such as double or String. Images might be downloaded automatically or returned as URL values. Their pixel-to-dpi scales can also vary.

To help you manage these details, the Google Mobile Ads SDK provides the NativeAd.Image class. In much the same way that you need to create a subclass of UnifiedNativeAdMapper to map a mediated native ad, you should also create a subclass of NativeAd.Image when mapping image assets.

Here's an example for the custom event's SampleNativeMappedImage class:

public class SampleNativeMappedImage extends NativeAd.Image {

  private Drawable drawable;
  private Uri imageUri;
  private double scale;

  public SampleNativeMappedImage(Drawable drawable, Uri imageUri, double scale) {
    this.drawable = drawable;
    this.imageUri = imageUri;
    this.scale = scale;
  }

  @Override
  public Drawable getDrawable() {
    return drawable;
  }

  @Override
  public Uri getUri() {
    return imageUri;
  }

  @Override
  public double getScale() {
    return scale;
  }
}

The SampleNativeAdMapper uses its mapped image class in this line to set the mapper's icon image asset:

setIcon(new SampleNativeMappedImage(ad.getAppIcon(), ad.getAppIconUri(),
    SampleCustomEvent.SAMPLE_SDK_IMAGE_SCALE));

Add fields to the extras Bundle

Some mediated SDKs provide additional assets beyond those in the AdMob native ad format. The UnifiedNativeAdMapper class includes a setExtras() method that is used to pass these assets to publishers. The SampleNativeAdMapper makes use of this for the Sample SDK's "degree of awesomeness" asset:

Bundle extras = new Bundle();
extras.putString(SampleCustomEvent.DEGREE_OF_AWESOMENESS, ad.getDegreeOfAwesomeness());
this.setExtras(extras);

Publishers can retrieve the data using the NativeAd class' getExtras() method.

AdChoices

Your custom event is responsible for providing an AdChoices icon using the setAdChoicesContent() method on UnifiedNativeAdMapper. Here's a snippet from SampleNativeAdMapper showing how to provide the AdChoices icon:

public SampleNativeAdMapper(SampleNativeAd ad) {
    ...
    setAdChoicesContent(sampleAd.getInformationIcon());
}

Impression and click events

Both the Google Mobile Ads SDK and the mediated SDK need to know when an impression or click occurs, but only one SDK needs to track these events. There are two different approaches custom events can use, depending on whether the mediated SDK supports tracking impressions and clicks on its own.

Track clicks and impressions with the Google Mobile Ads SDK

If the mediated SDK doesn't perform its own impression and click tracking but provides methods to record clicks and impressions, the Google Mobile Ads SDK can track these events and notify the adapter. The UnifiedNativeAdMapper class includes two methods: recordImpression() and handleClick() that custom events can implement to call the corresponding method on the mediated native ad object:

@Override
public void recordImpression() {
  sampleAd.recordImpression();
}

@Override
public void handleClick(View view) {
  sampleAd.handleClick(view);
}

Because the SampleNativeAdMapper holds a reference to the Sample SDK's native ad object, it can call the appropriate method on that object to report a click or impression. Note that the handleClick() method takes a single parameter: the View object corresponding to the native ad asset that received the click.

Track clicks and impressions with the mediated SDK

Some mediated SDKs might prefer to track clicks and impressions on their own. In that case, you should override the default click and impression tracking by making the following two calls in the constructor of your UnifiedNativeAdMapper:

setOverrideClickHandling(true);
setOverrideImpressionRecording(true);

Custom events that override click and impression tracking are required to report the onAdClicked() and onAdImpression() events to the Google Mobile Ads SDK.

To track impressions and clicks, the mediated SDK probably needs access to the views to enable the tracking. The custom event should override the trackViews() method and use it to pass the native ad's view to the mediated SDK to track. The sample SDK from our custom event example project (from which this guide's code snippets have been taken) doesn't use this approach; but if it did, the custom event code would look something like this:

@Override
public void trackViews(View containerView,
    Map<String, View> clickableAssetViews,
    Map<String, View> nonClickableAssetViews) {
  sampleAd.setNativeAdViewForTracking(containerView);
}

If the mediated SDK supports tracking individual assets, it can look inside clickableAssetViews to see which views should be made clickable. This map is keyed by an asset name in NativeAdAssetNames. The UnifiedNativeAdMapper offers a corresponding untrackView() method that custom events can override to release any references to the view and disassociate it from the native ad object.

Forward mediation events to the Google Mobile Ads SDK

You can find all the callbacks that mediation supports in the MediationNativeAdCallback docs.

It's important that your custom event forwards as many of these callbacks as possible, so that your app receives these equivalent events from the Google Mobile Ads SDK. Here's an example of using callbacks:

This completes the custom events implementation for native ads. The full example is available on GitHub.