React-native-firebase: 🔥 Firestore collectionGroup.where.onSnapshot query chain calls onNext with null snapshot

[aibtcare]

Issue

Describe your issue here
I set up a onSnapshot listener for a collectionGroup().where() query and noticed the onNext callback will get called twice. Once with the snapshot query (expected behavior) and then immediately afterwords with a null snapshot parameter. Not sure if this is expected behavior or not, but the Typescript definitions don't indicate the snapshot parameter can be null. This happens on iOS for me, not sure if it happens on Android as well.

Here is what my code looks like:

firestore() .collectionGroup(FCN.quotes) .where('workerId', '==', currentUser.uid) .onSnapshot(snapshot => { console.log(snapshot) })

---

Project Files

Javascript

Click To Expand

#### `package.json`:

{
    "name": "SquirrelWorker",
    "version": "6.3.0",
    "private": true,
    "scripts": {
        "start": "react-native start --port=9000",
        "run:android": "react-native run-android",
        "run:ios": "react-native run-ios --simulator=\"iPhone X\"",
        "build:apk": "cd android && ./gradlew assembleRelease",
        "test": "jest",
        "prepare": "patch-package"
    },
    "dependencies": {
        "@react-native-community/async-storage": "^1.7.1",
        "@react-native-community/datetimepicker": "^2.2.1",
        "@react-native-community/masked-view": "^0.1.6",
        "@react-native-community/push-notification-ios": "^1.0.5",
        "@react-native-firebase/app": "6.3.1",
        "@react-native-firebase/auth": "6.3.1",
        "@react-native-firebase/firestore": "6.3.1",
        "@react-native-firebase/functions": "6.3.1",
        "@react-native-firebase/messaging": "6.3.1",
        "@react-native-firebase/storage": "6.3.1",
        "@react-navigation/bottom-tabs": "^5.0.0",
        "@react-navigation/native": "^5.0.0",
        "@react-navigation/stack": "^5.0.0",
        "@types/react-native-push-notification": "^3.0.7",
        "@types/uuid": "^3.4.7",
        "axios": "^0.19.2",
        "moment": "^2.24.0",
        "react": "16.9.0",
        "react-native": "0.61.5",
        "react-native-config": "^0.12.0",
        "react-native-gesture-handler": "^1.5.6",
        "react-native-image-picker": "^2.2.1",
        "react-native-push-notification": "^3.1.9",
        "react-native-reanimated": "^1.7.0",
        "react-native-safe-area-context": "^0.7.0",
        "react-native-screens": "^2.0.0-beta.2",
        "uuid": "^3.4.0"
    },
    "devDependencies": {
        "@babel/core": "^7.6.2",
        "@babel/runtime": "^7.6.2",
        "@react-native-community/cli": "^2.9.0",
        "@react-native-community/eslint-config": "^0.0.5",
        "@types/react": "^16.9.19",
        "@types/react-native": "^0.61.10",
        "babel-jest": "^24.9.0",
        "eslint": "^6.5.1",
        "jest": "^24.9.0",
        "metro-react-native-babel-preset": "^0.56.0",
        "patch-package": "^6.1.4",
        "react-native-typescript-transformer": "^1.2.13",
        "react-test-renderer": "16.9.0",
        "typescript": "^3.7.5"
    },
    "jest": {
        "preset": "react-native"
    }
}

#### `firebase.json` for react-native-firebase v6:

{
  "react-native": {}
}

### iOS

Click To Expand

#### `ios/Podfile`: - [ ] I'm not using Pods - [x] I'm using Pods and my Podfile looks like:

platform :ios, '10.0'
require_relative '../node_modules/@react-native-community/cli-platform-ios/native_modules'

# To override the React Native Firebase iOS SDK versions used uncomment any of the below and change the version
# $FirebaseSDKVersion = '6.8.1'
# $FabricSDKVersion = '1.6.0'
# $CrashlyticsSDKVersion = '3.1.0'

target 'SquirrelWorker' do
  # Pods for SquirrelWorker
  pod 'FBLazyVector', :path => "../node_modules/react-native/Libraries/FBLazyVector"
  pod 'FBReactNativeSpec', :path => "../node_modules/react-native/Libraries/FBReactNativeSpec"
  pod 'RCTRequired', :path => "../node_modules/react-native/Libraries/RCTRequired"
  pod 'RCTTypeSafety', :path => "../node_modules/react-native/Libraries/TypeSafety"
  pod 'React', :path => '../node_modules/react-native/'
  pod 'React-Core', :path => '../node_modules/react-native/'
  pod 'React-CoreModules', :path => '../node_modules/react-native/React/CoreModules'
  pod 'React-Core/DevSupport', :path => '../node_modules/react-native/'
  pod 'React-RCTActionSheet', :path => '../node_modules/react-native/Libraries/ActionSheetIOS'
  pod 'React-RCTAnimation', :path => '../node_modules/react-native/Libraries/NativeAnimation'
  pod 'React-RCTBlob', :path => '../node_modules/react-native/Libraries/Blob'
  pod 'React-RCTImage', :path => '../node_modules/react-native/Libraries/Image'
  pod 'React-RCTLinking', :path => '../node_modules/react-native/Libraries/LinkingIOS'
  pod 'React-RCTNetwork', :path => '../node_modules/react-native/Libraries/Network'
  pod 'React-RCTSettings', :path => '../node_modules/react-native/Libraries/Settings'
  pod 'React-RCTText', :path => '../node_modules/react-native/Libraries/Text'
  pod 'React-RCTVibration', :path => '../node_modules/react-native/Libraries/Vibration'
  pod 'React-Core/RCTWebSocket', :path => '../node_modules/react-native/'
  pod 'React-cxxreact', :path => '../node_modules/react-native/ReactCommon/cxxreact'
  pod 'React-jsi', :path => '../node_modules/react-native/ReactCommon/jsi'
  pod 'React-jsiexecutor', :path => '../node_modules/react-native/ReactCommon/jsiexecutor'
  pod 'React-jsinspector', :path => '../node_modules/react-native/ReactCommon/jsinspector'
  pod 'ReactCommon/jscallinvoker', :path => "../node_modules/react-native/ReactCommon"
  pod 'ReactCommon/turbomodule/core', :path => "../node_modules/react-native/ReactCommon"
  pod 'Yoga', :path => '../node_modules/react-native/ReactCommon/yoga'

  pod 'DoubleConversion', :podspec => '../node_modules/react-native/third-party-podspecs/DoubleConversion.podspec'
  pod 'glog', :podspec => '../node_modules/react-native/third-party-podspecs/glog.podspec'
  pod 'Folly', :podspec => '../node_modules/react-native/third-party-podspecs/Folly.podspec'

  target 'SquirrelWorkerTests' do
    inherit! :search_paths
    # Pods for testing
  end

  use_native_modules!
end

target 'SquirrelWorker-tvOS' do
  # Pods for SquirrelWorker-tvOS

  target 'SquirrelWorker-tvOSTests' do
    inherit! :search_paths
    # Pods for testing
  end

end

#### `AppDelegate.m`:

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#import "AppDelegate.h"

#import <Firebase.h>
#import <React/RCTBridge.h>
#import <React/RCTBundleURLProvider.h>
#import <React/RCTRootView.h>
#import <RNCPushNotificationIOS.h>

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
  if ([FIRApp defaultApp] == nil) {
    [FIRApp configure];
  }

  // define UNUserNotificationCenter
  UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];
  center.delegate = self;

  RCTBridge *bridge = [[RCTBridge alloc] initWithDelegate:self launchOptions:launchOptions];
  RCTRootView *rootView = [[RCTRootView alloc] initWithBridge:bridge
                                                   moduleName:@"SquirrelWorker"
                                            initialProperties:nil];

  rootView.backgroundColor = [[UIColor alloc] initWithRed:1.0f green:1.0f blue:1.0f alpha:1];

  self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
  UIViewController *rootViewController = [UIViewController new];
  rootViewController.view = rootView;
  self.window.rootViewController = rootViewController;
  [self.window makeKeyAndVisible];
  return YES;
}

// Required to register for notifications
- (void)application:(UIApplication *)application didRegisterUserNotificationSettings:(UIUserNotificationSettings *)notificationSettings
{
  [RNCPushNotificationIOS didRegisterUserNotificationSettings:notificationSettings];
}
// Required for the register event.
- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken
{
  [RNCPushNotificationIOS didRegisterForRemoteNotificationsWithDeviceToken:deviceToken];
}
// Required for the notification event. You must call the completion handler after handling the remote notification.
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler
{
  [RNCPushNotificationIOS didReceiveRemoteNotification:userInfo fetchCompletionHandler:completionHandler];
}
// Required for the registrationError event.
- (void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error
{
  [RNCPushNotificationIOS didFailToRegisterForRemoteNotificationsWithError:error];
}
// Required for the localNotification event.
- (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification
{
  [RNCPushNotificationIOS didReceiveLocalNotification:notification];
}

// Called when a notification is delivered to a foreground app.
-(void)userNotificationCenter:(UNUserNotificationCenter *)center willPresentNotification:(UNNotification *)notification withCompletionHandler:(void (^)(UNNotificationPresentationOptions options))completionHandler
{
  completionHandler(UNAuthorizationOptionSound | UNAuthorizationOptionAlert | UNAuthorizationOptionBadge);
}

- (NSURL *)sourceURLForBridge:(RCTBridge *)bridge
{
#if DEBUG
  return [[RCTBundleURLProvider sharedSettings] jsBundleURLForBundleRoot:@"index" fallbackResource:nil];
#else
  return [[NSBundle mainBundle] URLForResource:@"main" withExtension:@"jsbundle"];
#endif
}

@end

---

Android

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#### Have you converted to AndroidX? - [X] my application is an AndroidX application? - [X] I am using `android/gradle.settings` `jetifier=true` for Android compatibility? - [ ] I am using the NPM package `jetifier` for react-native compatibility? #### `android/build.gradle`:

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    ext {
        buildToolsVersion = "28.0.3"
        minSdkVersion = 16
        compileSdkVersion = 28
        targetSdkVersion = 28
    }
    repositories {
        google()
        jcenter()
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.3'
        classpath 'com.google.gms:google-services:4.2.0'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        mavenLocal()
        maven {
            // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
            url("$rootDir/../node_modules/react-native/android")
        }
        maven {
            // Android JSC is installed from npm
            url("$rootDir/../node_modules/jsc-android/dist")
        }

        google()
        jcenter()
        maven { url 'https://jitpack.io' }
    }
}

#### `android/app/build.gradle`:

apply plugin: "com.android.application"
apply from: project(':react-native-config').projectDir.getPath() + "/dotenv.gradle"

import com.android.build.OutputFile

/**
 * The react.gradle file registers a task for each build variant (e.g. bundleDebugJsAndAssets
 * and bundleReleaseJsAndAssets).
 * These basically call `react-native bundle` with the correct arguments during the Android build
 * cycle. By default, bundleDebugJsAndAssets is skipped, as in debug/dev mode we prefer to load the
 * bundle directly from the development server. Below you can see all the possible configurations
 * and their defaults. If you decide to add a configuration block, make sure to add it before the
 * `apply from: "../../node_modules/react-native/react.gradle"` line.
 *
 * project.ext.react = [
 *   // the name of the generated asset file containing your JS bundle
 *   bundleAssetName: "index.android.bundle",
 *
 *   // the entry file for bundle generation
 *   entryFile: "index.android.js",
 *
 *   // https://facebook.github.io/react-native/docs/performance#enable-the-ram-format
 *   bundleCommand: "ram-bundle",
 *
 *   // whether to bundle JS and assets in debug mode
 *   bundleInDebug: false,
 *
 *   // whether to bundle JS and assets in release mode
 *   bundleInRelease: true,
 *
 *   // whether to bundle JS and assets in another build variant (if configured).
 *   // See http://tools.android.com/tech-docs/new-build-system/user-guide#TOC-Build-Variants
 *   // The configuration property can be in the following formats
 *   //         'bundleIn${productFlavor}${buildType}'
 *   //         'bundleIn${buildType}'
 *   // bundleInFreeDebug: true,
 *   // bundleInPaidRelease: true,
 *   // bundleInBeta: true,
 *
 *   // whether to disable dev mode in custom build variants (by default only disabled in release)
 *   // for example: to disable dev mode in the staging build type (if configured)
 *   devDisabledInStaging: true,
 *   // The configuration property can be in the following formats
 *   //         'devDisabledIn${productFlavor}${buildType}'
 *   //         'devDisabledIn${buildType}'
 *
 *   // the root of your project, i.e. where "package.json" lives
 *   root: "../../",
 *
 *   // where to put the JS bundle asset in debug mode
 *   jsBundleDirDebug: "$buildDir/intermediates/assets/debug",
 *
 *   // where to put the JS bundle asset in release mode
 *   jsBundleDirRelease: "$buildDir/intermediates/assets/release",
 *
 *   // where to put drawable resources / React Native assets, e.g. the ones you use via
 *   // require('./image.png')), in debug mode
 *   resourcesDirDebug: "$buildDir/intermediates/res/merged/debug",
 *
 *   // where to put drawable resources / React Native assets, e.g. the ones you use via
 *   // require('./image.png')), in release mode
 *   resourcesDirRelease: "$buildDir/intermediates/res/merged/release",
 *
 *   // by default the gradle tasks are skipped if none of the JS files or assets change; this means
 *   // that we don't look at files in android/ or ios/ to determine whether the tasks are up to
 *   // date; if you have any other folders that you want to ignore for performance reasons (gradle
 *   // indexes the entire tree), add them here. Alternatively, if you have JS files in android/
 *   // for example, you might want to remove it from here.
 *   inputExcludes: ["android/**", "ios/**"],
 *
 *   // override which node gets called and with what additional arguments
 *   nodeExecutableAndArgs: ["node"],
 *
 *   // supply additional arguments to the packager
 *   extraPackagerArgs: []
 * ]
 */

project.ext.react = [
    entryFile: "index.js",
    enableHermes: false,  // clean and rebuild if changing
]

apply from: "../../node_modules/react-native/react.gradle"

/**
 * Set this to true to create two separate APKs instead of one:
 *   - An APK that only works on ARM devices
 *   - An APK that only works on x86 devices
 * The advantage is the size of the APK is reduced by about 4MB.
 * Upload all the APKs to the Play Store and people will download
 * the correct one based on the CPU architecture of their device.
 */
def enableSeparateBuildPerCPUArchitecture = false

/**
 * Run Proguard to shrink the Java bytecode in release builds.
 */
def enableProguardInReleaseBuilds = false

/**
 * The preferred build flavor of JavaScriptCore.
 *
 * For example, to use the international variant, you can use:
 * `def jscFlavor = 'org.webkit:android-jsc-intl:+'`
 *
 * The international variant includes ICU i18n library and necessary data
 * allowing to use e.g. `Date.toLocaleString` and `String.localeCompare` that
 * give correct results when using with locales other than en-US.  Note that
 * this variant is about 6MiB larger per architecture than default.
 */
def jscFlavor = 'org.webkit:android-jsc:+'

/**
 * Whether to enable the Hermes VM.
 *
 * This should be set on project.ext.react and mirrored here.  If it is not set
 * on project.ext.react, JavaScript will not be compiled to Hermes Bytecode
 * and the benefits of using Hermes will therefore be sharply reduced.
 */
def enableHermes = project.ext.react.get("enableHermes", false);

android {
    compileSdkVersion rootProject.ext.compileSdkVersion

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    defaultConfig {
        applicationId "io.squirreltech.squirrelWorker"
        minSdkVersion rootProject.ext.minSdkVersion
        targetSdkVersion rootProject.ext.targetSdkVersion
        versionCode 1
        versionName "1.0"
        aaptOptions{
            noCompress "tflite","model"
        }
        resValue "string", "build_config_package", "io.squirreltech.squirrelWorker"
        multiDexEnabled true
    }
    splits {
        abi {
            reset()
            enable enableSeparateBuildPerCPUArchitecture
            universalApk false  // If true, also generate a universal APK
            include "armeabi-v7a", "x86", "arm64-v8a", "x86_64"
        }
    }
    signingConfigs {
        debug {
            storeFile file('debug.keystore')
            storePassword 'android'
            keyAlias 'androiddebugkey'
            keyPassword 'android'
        }
    }
    buildTypes {
        debug {
            signingConfig signingConfigs.debug
        }
        release {
            // Caution! In production, you need to generate your own keystore file.
            // see https://facebook.github.io/react-native/docs/signed-apk-android.
            signingConfig signingConfigs.debug
            minifyEnabled enableProguardInReleaseBuilds
            proguardFiles getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro"
        }
    }
    // applicationVariants are e.g. debug, release
    applicationVariants.all { variant ->
        variant.outputs.each { output ->
            // For each separate APK per architecture, set a unique version code as described here:
            // https://developer.android.com/studio/build/configure-apk-splits.html
            def versionCodes = ["armeabi-v7a": 1, "x86": 2, "arm64-v8a": 3, "x86_64": 4]
            def abi = output.getFilter(OutputFile.ABI)
            if (abi != null) {  // null for the universal-debug, universal-release variants
                output.versionCodeOverride =
                        versionCodes.get(abi) * 1048576 + defaultConfig.versionCode
            }

        }
    }
}

dependencies {
    implementation fileTree(dir: "libs", include: ["*.jar"])
    implementation "com.facebook.react:react-native:+"  // From node_modules
    implementation 'androidx.appcompat:appcompat:1.1.0-rc01'
    implementation 'androidx.swiperefreshlayout:swiperefreshlayout:1.1.0-alpha02'

    if (enableHermes) {
        def hermesPath = "../../node_modules/hermes-engine/android/";
        debugImplementation files(hermesPath + "hermes-debug.aar")
        releaseImplementation files(hermesPath + "hermes-release.aar")
    } else {
        implementation jscFlavor
    }
}

// Run this once to be able to run the application with BUCK
// puts all compile dependencies into folder libs for BUCK to use
task copyDownloadableDepsToLibs(type: Copy) {
    from configurations.compile
    into 'libs'
}

apply from: file("../../node_modules/@react-native-community/cli-platform-android/native_modules.gradle"); applyNativeModulesAppBuildGradle(project)
apply plugin: 'com.google.gms.google-services'

#### `android/settings.gradle`:

rootProject.name = 'SquirrelWorker'
apply from: file("../node_modules/@react-native-community/cli-platform-android/native_modules.gradle"); applyNativeModulesSettingsGradle(settings)

include ':react-native-push-notification'
project(':react-native-push-notification').projectDir = file('../node_modules/react-native-push-notification/android')

include ':app'

#### `MainApplication.java`:

package io.squirreltech.squirrelWorker;

import com.facebook.react.ReactActivity;
import com.facebook.react.ReactActivityDelegate;
import com.facebook.react.ReactRootView;
import com.swmansion.gesturehandler.react.RNGestureHandlerEnabledRootView;

public class MainActivity extends ReactActivity {

    /**
     * Returns the name of the main component registered from JavaScript.
     * This is used to schedule rendering of the component.
     */
    @Override
    protected String getMainComponentName() {
        return "SquirrelWorker";
    }

    @Override
    protected ReactActivityDelegate createReactActivityDelegate() {
        return new ReactActivityDelegate(this, getMainComponentName()) {
            @Override
            protected ReactRootView createRootView() {
                return new RNGestureHandlerEnabledRootView(MainActivity.this);
            }
        };
    }
}

#### `AndroidManifest.xml`:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="io.squirreltech.squirrelWorker">

    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <permission
        android:name="${applicationId}.permission.C2D_MESSAGE"
        android:protectionLevel="signature" />
    <uses-permission android:name="${applicationId}.permission.C2D_MESSAGE" />
    <!-- < Only if you're using GCM or localNotificationSchedule() > -->
    <uses-permission android:name="android.permission.VIBRATE" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>

    <uses-permission android:name="android.permission.INTERNET" />

    <!--  react-native-image-picker  -->
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

    <application
      android:name="io.squirreltech.squirrelWorker.MainApplication"
      android:label="@string/app_name"
      android:icon="@mipmap/ic_launcher"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:allowBackup="false"
      android:theme="@style/AppTheme">

        <receiver android:name="com.dieam.reactnativepushnotification.modules.RNPushNotificationPublisher" />
        <receiver android:name="com.dieam.reactnativepushnotification.modules.RNPushNotificationBootEventReceiver">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
            </intent-filter>
        </receiver>
        <service android:name="com.dieam.reactnativepushnotification.modules.RNPushNotificationRegistrationService"/>

        <!-- < Only if you're using GCM or localNotificationSchedule() > -->
        <service
            android:name="com.dieam.reactnativepushnotification.modules.RNPushNotificationListenerServiceGcm"
            android:exported="false" >
            <intent-filter>
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
            </intent-filter>
        </service>
        <!-- </ Only if you're using GCM or localNotificationSchedule() > -->

        <!-- < Else > -->
        <service
            android:name="com.dieam.reactnativepushnotification.modules.RNPushNotificationListenerService"
            android:exported="false" >
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>
        <!-- </Else> -->

      <activity
        android:name="io.squirreltech.squirrelWorker.MainActivity"
        android:label="@string/app_name"
        android:configChanges="keyboard|keyboardHidden|orientation|screenSize"
        android:windowSoftInputMode="adjustResize">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
      </activity>
      <activity android:name="com.facebook.react.devsupport.DevSettingsActivity" />
    </application>

</manifest>

---

Environment

Click To Expand

**`react-native info` output:**

System:
    OS: macOS 10.15.3
    CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
    Memory: 55.43 MB / 16.00 GB
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 13.11.0 - /usr/local/bin/node
    npm: 6.13.7 - /usr/local/bin/npm
    Watchman: 4.9.0 - /usr/local/bin/watchman
  SDKs:
    iOS SDK:
      Platforms: iOS 13.2, DriverKit 19.0, macOS 10.15, tvOS 13.2, watchOS 6.1
    Android SDK:
      API Levels: 22, 23, 28, 29
      Build Tools: 23.0.1, 24.0.1, 28.0.3, 29.0.0
      System Images: android-28 | Google APIs Intel x86 Atom, android-29 | Google APIs Intel x86 Atom_64
  IDEs:
    Android Studio: 3.5 AI-191.8026.42.35.6010548
    Xcode: 11.3.1/11C504 - /usr/bin/xcodebuild
  npmPackages:
    @react-native-community/cli: ^2.9.0 => 2.10.0 
    react: 16.9.0 => 16.9.0 
    react-native: 0.61.5 => 0.61.5

- **Platform that you're experiencing the issue on**: - [ ] iOS - [ ] Android - [X ] **iOS** but have not tested behavior on Android - [ ] **Android** but have not tested behavior on iOS - [ ] Both - **`react-native-firebase` version you're using that has this issue:** - `6.3.1` - **`Firebase` module(s) you're using that has the issue:** - `Firestore` - **Are you using `TypeScript`?** - `Y` & `3.7.5`

---

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[aibtcare]

Accidentally submitted before finishing the template, my bad!

[Ehesp]

Does this happen without the where statement?

[aibtcare]

Does this happen without the where statement?

Nope, seems to work good without the where.

[russellwheatley]

Hi @aibtcare, That null value is because you're querying across multiple collections. Unfortunately, there is no warning/error coming from the native side to let you know that is the problem.

One way you could fix it is to head over to your firebase console. Click "Databases", "Indexes" & finally "Single Field".

Click "Add Exemption" and create an exception for a collectionGroup on the field workerId. Hope this helps.

We'll try and improve the console warning to inform developers of this potential issue.

[aibtcare]

Hi @aibtcare, That null value is because you're querying across multiple collections. Unfortunately, there is no warning/error coming from the native side to let you know that is the problem.

Ah that's unfortunate. I just added the exemptions to my project and it seems to fix the problem, so it shouldn't be a big deal. I appreciate the quick response!

[Ehesp]

@russellwheatley maybe one to flag up on the Firebase Android SDK repo?

[russellwheatley]

Hi @aibtcare after further investigation, it appears we are emitting an error. If you take a look at the docs, you can see that you can put an error handler on the onSnapshot listener. Or, if you prefer, you can also check the second argument like below in classic callback syntax:

 firestore()
      .collectionGroup(FCN.quotes)
      .where('workerId', '==', currentUser.uid)
      .onSnapshot((snapshot, error) => {
        if(error){
         // handle error
         }
        console.log(snapshot);
      });

[aibtcare]

Hi @aibtcare after further investigation, it appears we are emitting an error. If you take a look at the docs, you can see that you can put an error handler on the onSnapshot listener. Or, if you prefer, you can also check the second argument like below in classic callback syntax:

 firestore()
      .collectionGroup(FCN.quotes)
      .where('workerId', '==', currentUser.uid)
      .onSnapshot((snapshot, error) => {
        if(error){
         // handle error
         }
        console.log(snapshot);
      });

Awesome, this is a good way to approach it. I should have been handling errors from the start haha. Thanks again!!