Flutter Facebook App Events gives the error: kotlin.UninitializedPropertyAccessException: lateinit property appEventsLogger has not been initialized

Question

I am using the latest version of FaceBook App Events plugin in Flutter with the latest version of Flutter as well. On click event, I am calling the logEvent method like this:

facebookAppEvents.logEvent(
    name: 'Link Clicked',
    parameters: {'url': request.url},
);

where the facebookAppEvents defined and initialized in the class itself:

static final facebookAppEvents = FacebookAppEvents();

Advertiser tracking is working with no problem using the following statement:

facebookAppEvents.setAdvertiserTracking(enabled: true);

However, I am getting an exception when calling the logEvent method. The exception is:

E/MethodChannel#flutter.oddbit.id/facebook_app_events(26467): Failed to handle method call
E/MethodChannel#flutter.oddbit.id/facebook_app_events(26467): kotlin.UninitializedPropertyAccessException: lateinit property appEventsLogger has not been initialized

Flutter doctor has no problem nor warning. I tried to clean and rebuild the project but still getting the same exception. All the tests I did are on Android only. Any way to fix this?

Answer 1

This library has a bug in it's source code. If you paste the exact stack trace I might be able to pin point the bug and maybe send a patch to the library owner for review.

Their code (where "appEventsLogger" is defined): https://github.com/oddbit/flutter_facebook_app_events/blob/develop/android/src/main/kotlin/id/oddbit/flutter/facebook_app_events/FacebookAppEventsPlugin.kt

Answer 2

I added ApplicationId meta data only because the flutter plugin documentation said so and got the error. But then solved it by adding ClientToken to AndroidManifest.xml ( you should add facebook_client_token as a string resource as well )

AndroidManifest.xml

<application android:label="@string/app_name" ...>

    <meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/facebook_app_id"/>
    <meta-data android:name="com.facebook.sdk.ClientToken" android:value="@string/facebook_client_token"/>

</application>

strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="facebook_app_id">123123</string>
    <string name="facebook_client_token">456456</string>
</resources>

More Info: https://developers.facebook.com/docs/app-events/getting-started-app-events-android