Flutter Local Notifications and Cloud Firestore Queries in the BACKGROUND

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2 mins

9 May 2021

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So a project i’ve been working on recently needed a module where i had to receive user notifications in the background and also refresh user’s info as soon as the notification was delivered to a user .
Now, this could’ve been done using the cloud function we were using to send the notification. but we needed to refresh the data only when the user received notification.
so LESGOOOOOOOO!
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the plugins we’ll need:
flutter_local_notifications: cloud_store: firebase_messaging:
make sure you’ve set these up before proceeding
run the app once and find the **GeneratedPluginRegistrant.java **file in android/app/src/main/java/io/flutter/plugins. we’ll need these to identify the import names later.
now head over to the folder containing **MainActivity.kt **and here we’ll create a registrant class.
CloudFirestorePluginRegistrant.kt
package <com.your.application> import android.util.Log import io.flutter.plugin.common.PluginRegistry import io.flutter.plugins.firebase.cloudfirestore.CloudFirestorePlugin class CloudFirestorePluginRegistrant { companion object { fun registerWith(registry: PluginRegistry){ Log.d("CloudFirestore", "registerWith"); if(alreadyRegisteredWith(registry)) { Log.d("Already Registered",""); return } try { CloudFirestorePlugin.registerWith(registry.registrarFor("io.flutter.plugins.firebase.cloudfirestore.CloudFirestorePlugin")) } catch (e: Exception) { Log.d("CloudFirestore", e.toString());} Log.d("Plugin Registered",""); } private fun alreadyRegisteredWith(registry: PluginRegistry): Boolean { val key = CloudFirestorePluginRegistrant::class.java.canonicalName if (registry.hasPlugin(key)) { return true } registry.registrarFor(key) return false } } }
and now lets register this class in our **Application.kt **in the same folder
package <com.your.application> import io.flutter.app.FlutterApplication import io.flutter.plugin.common.PluginRegistry import com.your.application.CloudFirestorePluginRegistrant class Application : FlutterApplication(), PluginRegistry.PluginRegistrantCallback { override fun onCreate() { super.onCreate() } override fun registerWith(registry: PluginRegistry?) { if (registry != null) { CloudFirestorePluginRegistrant.registerWith(registry) }} }
and thats about it.
Note: remember to omit “notification” key from our payload to trigger onBackgroundMessage callback.
now we can simply call this code in our firebase messaging onBackgroundMessage callback:
onBackgroundMessage: _onMyBackGroundMessage; _onMybackGroundMessage(Map<String,dynamic> message){ firestore.instance.collection(message['data'['userName']) .document(notfication).set({name:['data']['userName]}); }
and now we can make cloud firestore queries even if the app is in background.
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