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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