Background-Fetch: Cannot read property 'configure' of Undefined

I have been trying to integrate the transistorsoft background-fetch library without success.

When I chain any method to the BackgroundFetch component I get the error:

import BackgroundFetch from "react-native-background-fetch";

  class TimerScreen extends React.Component {

...

componentDidMount() {

    this.configureBackgroundFetch();

}
...
configureBackgroundFetch() {
    // Configure BackgroundFetch.
    BackgroundFetch.configure({
      minimumFetchInterval: 15, // <-- minutes (15 is minimum allowed)
      stopOnTerminate: false, // <-- Android-only,
      startOnBoot: true, // <-- Android-only
      enableHeadless: true
    }, async () => {
      console.log('BackgroundFetch has started');
      BackgroundFetch.finish(BackgroundFetch.FETCH_RESULT_NEW_DATA);
    }, (error) => {
      console.log('RNBackgroundFetch failed to start')
    });
}
...

I haven’t been able to find out why the library isn’t working. I have used react native link and installed it in package.json

 ...
 {
       ...
       "react-native-background-fetch": "^2.5.3",
       ...
 }
 ...

Your Environment

• Plugin version: 2.5.3
• Platform: iOS or Android
• OS version: Linux
• Device manufacturer / model: Lenovo PC
• React Native version (react-native -v): react-native-cli: 2.0.1 react-native: 0.57.1
• Plugin config: Just added these two commands - $ npm install --save react-native-background-fetch $ react-native link react-native-background-fetch

Expected Behavior

The BackgroundFetch should be confiugred and run in the background every 15 minutes.

Actual Behavior

Error whenever any method from the plugin is chained to the BackgroundFetch

Steps to Reproduce

1. Install react-native-background-fetch and use link it
2. Import library
3. Write function for configuring BackgroundFetch
4. Execute the function in componentDidMount lifecycle method.

Context

I am trying to run a background task that will ping an API in the background while the app is in the background or the phone is locked.

Debug logs

04-25 12:52:30.467  4759  4759 E EventBus: Could not dispatch event: class com.transistorsoft.locationmanager.event.HeadlessEvent to subscribing class class com.transistorsoft.rnbackgroundgeolocation.HeadlessTask
04-25 12:52:30.467  4759  4759 E EventBus: java.lang.ClassCastException: com.transistorsoft.locationmanager.service.HeartbeatService cannot be cast to com.facebook.react.ReactApplication
04-25 12:52:30.467  4759  4759 E EventBus:      at com.transistorsoft.rnbackgroundgeolocation.HeadlessTask.startTask(HeadlessTask.java:109)
04-25 12:52:30.467  4759  4759 E EventBus:      at com.transistorsoft.rnbackgroundgeolocation.HeadlessTask.onHeadlessEvent(HeadlessTask.java:95)
04-25 12:52:30.467  4759  4759 E EventBus:      at java.lang.reflect.Method.invoke(Native Method)
04-25 12:52:30.467  4759  4759 E EventBus:      at org.greenrobot.eventbus.EventBus.invokeSubscriber(EventBus.java:485)
04-25 12:52:30.467  4759  4759 E EventBus:      at org.greenrobot.eventbus.EventBus.postToSubscription(EventBus.java:420)
04-25 12:52:30.467  4759  4759 E EventBus:      at org.greenrobot.eventbus.EventBus.postSingleEventForEventType(EventBus.java:397)
04-25 12:52:30.467  4759  4759 E EventBus:      at org.greenrobot.eventbus.EventBus.postSingleEvent(EventBus.java:370)
04-25 12:52:30.467  4759  4759 E EventBus:      at org.greenrobot.eventbus.EventBus.post(EventBus.java:251)
04-25 12:52:30.467  4759  4759 E EventBus:      at com.transistorsoft.locationmanager.util.a.a(Unknown Source)
04-25 12:52:30.467  4759  4759 E EventBus:      at com.transistorsoft.locationmanager.service.HeartbeatService.onStartCommand(Unknown Source)
04-25 12:52:30.467  4759  4759 E EventBus:      at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3326)
04-25 12:52:30.467  4759  4759 E EventBus:      at android.app.ActivityThread.-wrap21(ActivityThread.java)
04-25 12:52:30.467  4759  4759 E EventBus:      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1582)
04-25 12:52:30.467  4759  4759 E EventBus:      at android.os.Handler.dispatchMessage(Handler.java:102)
04-25 12:52:30.467  4759  4759 E EventBus:      at android.os.Looper.loop(Looper.java:154)
04-25 12:52:30.467  4759  4759 E EventBus:      at android.app.ActivityThread.main(ActivityThread.java:6119)
04-25 12:52:30.467  4759  4759 E EventBus:      at java.lang.reflect.Method.invoke(Native Method)
04-25 12:52:30.467  4759  4759 E EventBus:      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
04-25 12:52:30.467  4759  4759 E EventBus:      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
04-25 12:52:30.467  4759  4759 D EventBus: No subscribers registered for event class org.greenrobot.eventbus.SubscriberExceptionEvent
04-25 12:52:30.467  1390  1415 W audio_hw_generic: Not supplying enough data to HAL, expected position 42494451 , only wrote 42494400
04-25 12:52:31.406  1398 14683 D NuPlayerDriver: notifyListener_l(0xaaf93180), (2, 0, 0), loop setting(0, 0)
04-25 12:52:31.406  1398  1408 D NuPlayerDriver: reset(0xaaf93180) at state 6
04-25 12:52:31.406  1398  1408 D NuPlayerDriver: notifyListener_l(0xaaf93180), (8, 0, 0), loop setting(0, 0)
04-25 12:52:31.408  1398 14683 W AMessage: failed to post message as target looper for handler 0 is gone.
04-25 12:52:31.409  1398 14683 D NuPlayerDriver: notifyResetComplete(0xaaf93180)
04-25 12:52:34.368  1390  1416 W audio_hw_generic: Not supplying enough data to HAL, expected position 42866716 , only wrote 42681600
04-25 12:52:34.442  4619 14567 D j       : WARNING: getPackageName called on ScopedContext
04-25 12:52:39.459  4619 14567 D j       : WARNING: getPackageName called on ScopedContext
04-25 12:52:44.475  4619 14567 D j       : WARNING: getPackageName called on ScopedContext
04-25 12:52:49.493  4619 14567 D j       : WARNING: getPackageName called on ScopedContext
04-25 12:52:54.509  4619 14567 D j       : WARNING: getPackageName called on ScopedContext
04-25 12:52:59.530  4619 14567 D j       : WARNING: getPackageName called on ScopedContext
04-25 12:53:04.543  4619 14567 D j       : WARNING: getPackageName called on ScopedContext
04-25 12:53:09.568  4619 14567 D j       : WARNING: getPackageName called on ScopedContext
04-25 12:53:14.575  4619 14567 D j       : WARNING: getPackageName called on ScopedContext

[christocracy]

Ahhh…ejected Expo. Good luck with that. I hate Expo.

[codeNameKC]

It was indeed the Expokit that was the culprit behind the problem. The Expokit setup wasn’t configured properly to run native code. I made a hello world app with Expokit and another one with a regular react native setup. The Expokit project failed to link without an error and the regular setup worked as it should.