[android][firestore] cleanup

android/src/main/java/io/invertase/firebase/Utils.java

@@ -1,20 +1,21 @@
 package io.invertase.firebase;
 
+import android.annotation.SuppressLint;
 import android.app.ActivityManager;
 import android.content.Context;
+import android.os.AsyncTask;
 import android.util.Log;
 
+import com.facebook.react.bridge.Arguments;
+import com.facebook.react.bridge.ReactContext;
+import com.facebook.react.bridge.ReadableArray;
+import com.facebook.react.bridge.ReadableMap;
+import com.facebook.react.bridge.WritableMap;
+import com.facebook.react.modules.core.DeviceEventManagerModule;
+
 import java.util.List;
 import java.util.Map;
 
-import com.facebook.react.bridge.Arguments;
-import com.facebook.react.bridge.WritableMap;
-import com.facebook.react.bridge.ReadableMap;
-import com.facebook.react.bridge.ReactContext;
-import com.facebook.react.modules.core.DeviceEventManagerModule;
-
-import com.facebook.react.bridge.ReadableArray;
-
 import javax.annotation.Nullable;
 
 

android/src/main/java/io/invertase/firebase/firestore/FirestoreSerialize.java

@@ -52,18 +52,16 @@ public class FirestoreSerialize {
     if (documentSnapshot.exists()) {
       documentMap.putMap(KEY_DATA, objectMapToWritable(documentSnapshot.getData()));
     }
+
     // metadata
-    if (documentSnapshot.getMetadata() != null) {
     WritableMap metadata = Arguments.createMap();
     metadata.putBoolean("fromCache", documentSnapshot.getMetadata().isFromCache());
     metadata.putBoolean("hasPendingWrites", documentSnapshot.getMetadata().hasPendingWrites());
     documentMap.putMap(KEY_METADATA, metadata);
-    }
-
     return documentMap;
   }
 
-  public static WritableMap snapshotToWritableMap(QuerySnapshot querySnapshot) {
+  static WritableMap snapshotToWritableMap(QuerySnapshot querySnapshot) {
     WritableMap queryMap = Arguments.createMap();
 
     List<DocumentChange> documentChanges = querySnapshot.getDocumentChanges();
@@ -78,12 +76,10 @@ public class FirestoreSerialize {
     queryMap.putArray(KEY_DOCUMENTS, documents);
 
     // metadata
-    if (querySnapshot.getMetadata() != null) {
     WritableMap metadata = Arguments.createMap();
     metadata.putBoolean("fromCache", querySnapshot.getMetadata().isFromCache());
     metadata.putBoolean("hasPendingWrites", querySnapshot.getMetadata().hasPendingWrites());
     queryMap.putMap(KEY_METADATA, metadata);
-    }
 
     return queryMap;
   }
@@ -94,7 +90,7 @@ public class FirestoreSerialize {
    * @param documentChanges List<DocumentChange>
    * @return WritableArray
    */
-  static WritableArray documentChangesToWritableArray(List<DocumentChange> documentChanges) {
+  private static WritableArray documentChangesToWritableArray(List<DocumentChange> documentChanges) {
     WritableArray documentChangesWritable = Arguments.createArray();
     for (DocumentChange documentChange : documentChanges) {
       documentChangesWritable.pushMap(documentChangeToWritableMap(documentChange));
@@ -108,7 +104,7 @@ public class FirestoreSerialize {
    * @param documentChange DocumentChange
    * @return WritableMap
    */
-  static WritableMap documentChangeToWritableMap(DocumentChange documentChange) {
+  private static WritableMap documentChangeToWritableMap(DocumentChange documentChange) {
     WritableMap documentChangeMap = Arguments.createMap();
 
     switch (documentChange.getType()) {
@@ -122,8 +118,10 @@ public class FirestoreSerialize {
         documentChangeMap.putString(KEY_DOC_CHANGE_TYPE, "modified");
     }
 
-    documentChangeMap.putMap(KEY_DOC_CHANGE_DOCUMENT,
+    documentChangeMap.putMap(
-      snapshotToWritableMap(documentChange.getDocument()));
+      KEY_DOC_CHANGE_DOCUMENT,
+      snapshotToWritableMap(documentChange.getDocument())
+    );
     documentChangeMap.putInt(KEY_DOC_CHANGE_NEW_INDEX, documentChange.getNewIndex());
     documentChangeMap.putInt(KEY_DOC_CHANGE_OLD_INDEX, documentChange.getOldIndex());
 
@@ -136,7 +134,7 @@ public class FirestoreSerialize {
    * @param map Map<String, Object>
    * @return WritableMap
    */
-  static WritableMap objectMapToWritable(Map<String, Object> map) {
+  private static WritableMap objectMapToWritable(Map<String, Object> map) {
     WritableMap writableMap = Arguments.createMap();
     for (Map.Entry<String, Object> entry : map.entrySet()) {
       WritableMap typeMap = buildTypeMap(entry.getValue());
@@ -224,7 +222,10 @@ public class FirestoreSerialize {
     return typeMap;
   }
 
-  static Map<String, Object> parseReadableMap(FirebaseFirestore firestore, ReadableMap readableMap) {
+  static Map<String, Object> parseReadableMap(
+    FirebaseFirestore firestore,
+    ReadableMap readableMap
+  ) {
     Map<String, Object> map = new HashMap<>();
     if (readableMap != null) {
       ReadableMapKeySetIterator iterator = readableMap.keySetIterator();
@@ -290,7 +291,10 @@ public class FirestoreSerialize {
     }
   }
 
-  public static List<Object> parseDocumentBatches(FirebaseFirestore firestore, ReadableArray readableArray) {
+  static List<Object> parseDocumentBatches(
+    FirebaseFirestore firestore,
+    ReadableArray readableArray
+  ) {
     List<Object> writes = new ArrayList<>(readableArray.size());
     for (int i = 0; i < readableArray.size(); i++) {
       Map<String, Object> write = new HashMap<>();

android/src/main/java/io/invertase/firebase/firestore/RNFirebaseFirestore.java

@@ -18,13 +18,13 @@ import com.google.android.gms.tasks.OnFailureListener;
 import com.google.android.gms.tasks.OnSuccessListener;
 import com.google.android.gms.tasks.Task;
 import com.google.firebase.FirebaseApp;
-import com.google.firebase.firestore.FirebaseFirestoreSettings;
-import com.google.firebase.firestore.Transaction;
 import com.google.firebase.firestore.DocumentReference;
 import com.google.firebase.firestore.FieldValue;
 import com.google.firebase.firestore.FirebaseFirestore;
 import com.google.firebase.firestore.FirebaseFirestoreException;
+import com.google.firebase.firestore.FirebaseFirestoreSettings;
 import com.google.firebase.firestore.SetOptions;
+import com.google.firebase.firestore.Transaction;
 import com.google.firebase.firestore.WriteBatch;
 
 import java.util.HashMap;
@@ -48,6 +48,184 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
    * REACT NATIVE METHODS
    */
 
+  /**
+   * Generates a js-like error from an exception and rejects the provided promise with it.
+   *
+   * @param exception Exception Exception normally from a task result.
+   * @param promise   Promise react native promise
+   */
+  static void promiseRejectException(Promise promise, FirebaseFirestoreException exception) {
+    WritableMap jsError = getJSError(exception);
+    promise.reject(
+      jsError.getString("code"),
+      jsError.getString("message"),
+      exception
+    );
+  }
+
+  /**
+   * Get a database instance for a specific firebase app instance
+   *
+   * @param appName appName
+   * @return FirebaseFirestore
+   */
+  static FirebaseFirestore getFirestoreForApp(String appName) {
+    FirebaseApp firebaseApp = FirebaseApp.getInstance(appName);
+    return FirebaseFirestore.getInstance(firebaseApp);
+  }
+
+  /**
+   * Convert as firebase DatabaseError instance into a writable map
+   * with the correct web-like error codes.
+   *
+   * @param nativeException nativeException
+   * @return WritableMap
+   */
+  static WritableMap getJSError(FirebaseFirestoreException nativeException) {
+    WritableMap errorMap = Arguments.createMap();
+    errorMap.putInt("nativeErrorCode", nativeException.getCode().value());
+    errorMap.putString("nativeErrorMessage", nativeException.getMessage());
+
+    String code;
+    String message;
+    String service = "Firestore";
+
+    // TODO: Proper error mappings
+    switch (nativeException.getCode()) {
+      case OK:
+        code = ErrorUtils.getCodeWithService(service, "ok");
+        message = ErrorUtils.getMessageWithService("Ok.", service, code);
+        break;
+      case CANCELLED:
+        code = ErrorUtils.getCodeWithService(service, "cancelled");
+        message = ErrorUtils.getMessageWithService("The operation was cancelled.", service, code);
+        break;
+      case UNKNOWN:
+        code = ErrorUtils.getCodeWithService(service, "unknown");
+        message = ErrorUtils.getMessageWithService(
+          "Unknown error or an error from a different error domain.",
+          service,
+          code
+        );
+        break;
+      case INVALID_ARGUMENT:
+        code = ErrorUtils.getCodeWithService(service, "invalid-argument");
+        message = ErrorUtils.getMessageWithService(
+          "Client specified an invalid argument.",
+          service,
+          code
+        );
+        break;
+      case DEADLINE_EXCEEDED:
+        code = ErrorUtils.getCodeWithService(service, "deadline-exceeded");
+        message = ErrorUtils.getMessageWithService(
+          "Deadline expired before operation could complete.",
+          service,
+          code
+        );
+        break;
+      case NOT_FOUND:
+        code = ErrorUtils.getCodeWithService(service, "not-found");
+        message = ErrorUtils.getMessageWithService(
+          "Some requested document was not found.",
+          service,
+          code
+        );
+        break;
+      case ALREADY_EXISTS:
+        code = ErrorUtils.getCodeWithService(service, "already-exists");
+        message = ErrorUtils.getMessageWithService(
+          "Some document that we attempted to create already exists.",
+          service,
+          code
+        );
+        break;
+      case PERMISSION_DENIED:
+        code = ErrorUtils.getCodeWithService(service, "permission-denied");
+        message = ErrorUtils.getMessageWithService(
+          "The caller does not have permission to execute the specified operation.",
+          service,
+          code
+        );
+        break;
+      case RESOURCE_EXHAUSTED:
+        code = ErrorUtils.getCodeWithService(service, "resource-exhausted");
+        message = ErrorUtils.getMessageWithService(
+          "Some resource has been exhausted, perhaps a per-user quota, or perhaps the entire file system is out of space.",
+          service,
+          code
+        );
+        break;
+      case FAILED_PRECONDITION:
+        code = ErrorUtils.getCodeWithService(service, "failed-precondition");
+        message = ErrorUtils.getMessageWithService(
+          "Operation was rejected because the system is not in a state required for the operation`s execution.",
+          service,
+          code
+        );
+        break;
+      case ABORTED:
+        code = ErrorUtils.getCodeWithService(service, "aborted");
+        message = ErrorUtils.getMessageWithService(
+          "The operation was aborted, typically due to a concurrency issue like transaction aborts, etc.",
+          service,
+          code
+        );
+        break;
+      case OUT_OF_RANGE:
+        code = ErrorUtils.getCodeWithService(service, "out-of-range");
+        message = ErrorUtils.getMessageWithService(
+          "Operation was attempted past the valid range.",
+          service,
+          code
+        );
+        break;
+      case UNIMPLEMENTED:
+        code = ErrorUtils.getCodeWithService(service, "unimplemented");
+        message = ErrorUtils.getMessageWithService(
+          "Operation is not implemented or not supported/enabled.",
+          service,
+          code
+        );
+        break;
+      case INTERNAL:
+        code = ErrorUtils.getCodeWithService(service, "internal");
+        message = ErrorUtils.getMessageWithService("Internal errors.", service, code);
+        break;
+      case UNAVAILABLE:
+        code = ErrorUtils.getCodeWithService(service, "unavailable");
+        message = ErrorUtils.getMessageWithService(
+          "The service is currently unavailable.",
+          service,
+          code
+        );
+        break;
+      case DATA_LOSS:
+        code = ErrorUtils.getCodeWithService(service, "data-loss");
+        message = ErrorUtils.getMessageWithService(
+          "Unrecoverable data loss or corruption.",
+          service,
+          code
+        );
+        break;
+      case UNAUTHENTICATED:
+        code = ErrorUtils.getCodeWithService(service, "unauthenticated");
+        message = ErrorUtils.getMessageWithService(
+          "The request does not have valid authentication credentials for the operation.",
+          service,
+          code
+        );
+        break;
+      default:
+        code = ErrorUtils.getCodeWithService(service, "unknown");
+        message = ErrorUtils.getMessageWithService("An unknown error occurred.", service, code);
+    }
+
+    errorMap.putString("code", code);
+    errorMap.putString("message", message);
+    return errorMap;
+  }
+
   @ReactMethod
   public void disableNetwork(String appName, final Promise promise) {
     getFirestoreForApp(appName).disableNetwork().addOnCompleteListener(new OnCompleteListener<Void>() {
@@ -58,7 +236,10 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
           promise.resolve(null);
         } else {
           Log.e(TAG, "disableNetwork:onComplete:failure", task.getException());
-          RNFirebaseFirestore.promiseRejectException(promise, (FirebaseFirestoreException)task.getException());
+          RNFirebaseFirestore.promiseRejectException(
+            promise,
+            (FirebaseFirestoreException) task.getException()
+          );
         }
       }
     });
@@ -83,35 +264,55 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
           promise.resolve(null);
         } else {
           Log.e(TAG, "enableNetwork:onComplete:failure", task.getException());
-          RNFirebaseFirestore.promiseRejectException(promise, (FirebaseFirestoreException)task.getException());
+          RNFirebaseFirestore.promiseRejectException(
+            promise,
+            (FirebaseFirestoreException) task.getException()
+          );
         }
       }
     });
   }
 
   @ReactMethod
-  public void collectionGet(String appName, String path, ReadableArray filters,
+  public void collectionGet(
+    String appName, String path, ReadableArray filters,
     ReadableArray orders, ReadableMap options, ReadableMap getOptions,
-                            final Promise promise) {
+    final Promise promise
-    RNFirebaseFirestoreCollectionReference ref = getCollectionForAppPath(appName, path, filters, orders, options);
+  ) {
+    RNFirebaseFirestoreCollectionReference ref = getCollectionForAppPath(
+      appName,
+      path,
+      filters,
+      orders,
+      options
+    );
     ref.get(getOptions, promise);
   }
 
   @ReactMethod
-  public void collectionOffSnapshot(String appName, String path, ReadableArray filters,
+  public void collectionOffSnapshot(
-                                    ReadableArray orders, ReadableMap options, String listenerId) {
+    String appName, String path, ReadableArray filters,
+    ReadableArray orders, ReadableMap options, String listenerId
+  ) {
     RNFirebaseFirestoreCollectionReference.offSnapshot(listenerId);
   }
 
   @ReactMethod
-  public void collectionOnSnapshot(String appName, String path, ReadableArray filters,
+  public void collectionOnSnapshot(
+    String appName, String path, ReadableArray filters,
     ReadableArray orders, ReadableMap options, String listenerId,
-                                   ReadableMap queryListenOptions) {
+    ReadableMap queryListenOptions
-    RNFirebaseFirestoreCollectionReference ref = getCollectionForAppPath(appName, path, filters, orders, options);
+  ) {
+    RNFirebaseFirestoreCollectionReference ref = getCollectionForAppPath(
+      appName,
+      path,
+      filters,
+      orders,
+      options
+    );
     ref.onSnapshot(listenerId, queryListenOptions);
   }
 
-
   @ReactMethod
   public void documentBatch(final String appName, final ReadableArray writes,
                             final Promise promise) {
@@ -166,7 +367,12 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
   }
 
   @ReactMethod
-  public void documentGet(String appName, String path, ReadableMap getOptions, final Promise promise) {
+  public void documentGet(
+    String appName,
+    String path,
+    ReadableMap getOptions,
+    final Promise promise
+  ) {
     RNFirebaseFirestoreDocumentReference ref = getDocumentForAppPath(appName, path);
     ref.get(getOptions, promise);
   }
@@ -177,18 +383,31 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
   }
 
   @ReactMethod
-  public void documentOnSnapshot(String appName, String path, String listenerId,
+  public void documentOnSnapshot(
-                                 ReadableMap docListenOptions) {
+    String appName, String path, String listenerId,
+    ReadableMap docListenOptions
+  ) {
     RNFirebaseFirestoreDocumentReference ref = getDocumentForAppPath(appName, path);
     ref.onSnapshot(listenerId, docListenOptions);
   }
 
   @ReactMethod
-  public void documentSet(String appName, String path, ReadableMap data, ReadableMap options, final Promise promise) {
+  public void documentSet(
+    String appName,
+    String path,
+    ReadableMap data,
+    ReadableMap options,
+    final Promise promise
+  ) {
     RNFirebaseFirestoreDocumentReference ref = getDocumentForAppPath(appName, path);
     ref.set(data, options, promise);
   }
 
+
+  /*
+   * Transaction Methods
+   */
+
   @ReactMethod
   public void documentUpdate(String appName, String path, ReadableMap data, final Promise promise) {
     RNFirebaseFirestoreDocumentReference ref = getDocumentForAppPath(appName, path);
@@ -214,18 +433,17 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
     } else {
       firestoreSettings.setSslEnabled(firestore.getFirestoreSettings().isSslEnabled());
     }
-    if (settings.hasKey("timestampsInSnapshots")) {
+
-      // TODO: Not supported on Android yet
+//    if (settings.hasKey("timestampsInSnapshots")) {
-    }
+//      // TODO: Not supported on Android yet
+//    }
 
     firestore.setFirestoreSettings(firestoreSettings.build());
     promise.resolve(null);
   }
 
-
   /**
    * Try clean up previous transactions on reload
-   *
    */
   @Override
   public void onCatalystInstanceDestroy() {
@@ -239,23 +457,22 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
     transactionHandlers.clear();
   }
 
-
-  /*
-   * Transaction Methods
-   */
-
-
   /**
    * Calls the internal Firestore Transaction classes instance .get(ref) method and resolves with
    * the DocumentSnapshot.
    *
-   * @param appName
+   * @param appName       appName
-   * @param transactionId
+   * @param transactionId transactionId
-   * @param path
+   * @param path          path
-   * @param promise
+   * @param promise       promise
    */
   @ReactMethod
-  public void transactionGetDocument(String appName, int transactionId, String path, final Promise promise) {
+  public void transactionGetDocument(
+    String appName,
+    int transactionId,
+    String path,
+    final Promise promise
+  ) {
     RNFirebaseFirestoreTransactionHandler handler = transactionHandlers.get(transactionId);
 
     if (handler == null) {
@@ -269,11 +486,16 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
     }
   }
 
+
+  /*
+   * INTERNALS/UTILS
+   */
+
   /**
    * Aborts any pending signals and deletes the transaction handler.
    *
-   * @param appName
+   * @param appName       appName
-   * @param transactionId
+   * @param transactionId transactionId
    */
   @ReactMethod
   public void transactionDispose(String appName, int transactionId) {
@@ -288,12 +510,16 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
   /**
    * Signals to transactionHandler that the command buffer is ready.
    *
-   * @param appName
+   * @param appName       appName
-   * @param transactionId
+   * @param transactionId transactionId
-   * @param commandBuffer
+   * @param commandBuffer commandBuffer
    */
   @ReactMethod
-  public void transactionApplyBuffer(String appName, int transactionId, ReadableArray commandBuffer) {
+  public void transactionApplyBuffer(
+    String appName,
+    int transactionId,
+    ReadableArray commandBuffer
+  ) {
     RNFirebaseFirestoreTransactionHandler handler = transactionHandlers.get(transactionId);
 
     if (handler != null) {
@@ -304,12 +530,16 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
   /**
    * Begin a new transaction via AsyncTask 's
    *
-   * @param appName
+   * @param appName       appName
-   * @param transactionId
+   * @param transactionId transactionId
    */
   @ReactMethod
   public void transactionBegin(final String appName, int transactionId) {
-    final RNFirebaseFirestoreTransactionHandler transactionHandler = new RNFirebaseFirestoreTransactionHandler(appName, transactionId);
+    final RNFirebaseFirestoreTransactionHandler transactionHandler = new RNFirebaseFirestoreTransactionHandler(
+      appName,
+      transactionId
+    );
+
     transactionHandlers.put(transactionId, transactionHandler);
 
     AsyncTask.execute(new Runnable() {
@@ -327,7 +557,11 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
                 @Override
                 public void run() {
                   WritableMap eventMap = transactionHandler.createEventMap(null, "update");
-                  Utils.sendEvent(getReactApplicationContext(), "firestore_transaction_event", eventMap);
+                  Utils.sendEvent(
+                    getReactApplicationContext(),
+                    "firestore_transaction_event",
+                    eventMap
+                  );
                 }
               });
 
@@ -336,12 +570,18 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
 
               // exit early if aborted - has to throw an exception otherwise will just keep trying ...
               if (transactionHandler.aborted) {
-                throw new FirebaseFirestoreException("abort", FirebaseFirestoreException.Code.ABORTED);
+                throw new FirebaseFirestoreException(
+                  "abort",
+                  FirebaseFirestoreException.Code.ABORTED
+                );
               }
 
               // exit early if timeout from bridge - has to throw an exception otherwise will just keep trying ...
               if (transactionHandler.timeout) {
-                throw new FirebaseFirestoreException("timeout", FirebaseFirestoreException.Code.DEADLINE_EXCEEDED);
+                throw new FirebaseFirestoreException(
+                  "timeout",
+                  FirebaseFirestoreException.Code.DEADLINE_EXCEEDED
+                );
               }
 
               // process any buffered commands from JS land
@@ -357,15 +597,19 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
                 ReadableMap command = buffer.getMap(i);
                 String path = command.getString("path");
                 String type = command.getString("type");
-                RNFirebaseFirestoreDocumentReference documentReference = getDocumentForAppPath(appName, path);
+                RNFirebaseFirestoreDocumentReference documentReference = getDocumentForAppPath(
-
+                  appName,
+                  path
+                );
 
                 switch (type) {
                   case "set":
                     data = command.getMap("data");
-
                     ReadableMap options = command.getMap("options");
-                    Map<String, Object> setData = FirestoreSerialize.parseReadableMap(RNFirebaseFirestore.getFirestoreForApp(appName), data);
+                    Map<String, Object> setData = FirestoreSerialize.parseReadableMap(
+                      RNFirebaseFirestore.getFirestoreForApp(appName),
+                      data
+                    );
 
                     if (options != null && options.hasKey("merge") && options.getBoolean("merge")) {
                       transaction.set(documentReference.getRef(), setData, SetOptions.merge());
@@ -376,7 +620,11 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
                   case "update":
                     data = command.getMap("data");
 
-                    Map<String, Object> updateData = FirestoreSerialize.parseReadableMap(RNFirebaseFirestore.getFirestoreForApp(appName), data);
+                    Map<String, Object> updateData = FirestoreSerialize.parseReadableMap(
+                      RNFirebaseFirestore.getFirestoreForApp(appName),
+                      data
+                    );
+
                     transaction.update(documentReference.getRef(), updateData);
                     break;
                   case "delete":
@@ -396,7 +644,11 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
               if (!transactionHandler.aborted) {
                 Log.d(TAG, "Transaction onSuccess!");
                 WritableMap eventMap = transactionHandler.createEventMap(null, "complete");
-                Utils.sendEvent(getReactApplicationContext(), "firestore_transaction_event", eventMap);
+                Utils.sendEvent(
+                  getReactApplicationContext(),
+                  "firestore_transaction_event",
+                  eventMap
+                );
               }
             }
           })
@@ -405,167 +657,60 @@ public class RNFirebaseFirestore extends ReactContextBaseJavaModule {
             public void onFailure(@NonNull Exception e) {
               if (!transactionHandler.aborted) {
                 Log.w(TAG, "Transaction onFailure.", e);
-                WritableMap eventMap = transactionHandler.createEventMap((FirebaseFirestoreException) e, "error");
+                WritableMap eventMap = transactionHandler.createEventMap(
-                Utils.sendEvent(getReactApplicationContext(), "firestore_transaction_event", eventMap);
+                  (FirebaseFirestoreException) e,
-              }
+                  "error"
-            }
+                );
-          });
+                Utils.sendEvent(
-      }
+                  getReactApplicationContext(),
-    });
+                  "firestore_transaction_event",
-  }
+                  eventMap
-
-
-  /*
-   * INTERNALS/UTILS
-   */
-
-  /**
-   * Generates a js-like error from an exception and rejects the provided promise with it.
-   *
-   * @param exception Exception Exception normally from a task result.
-   * @param promise   Promise react native promise
-   */
-  static void promiseRejectException(Promise promise, FirebaseFirestoreException exception) {
-    WritableMap jsError = getJSError(exception);
-    promise.reject(
-      jsError.getString("code"),
-      jsError.getString("message"),
-      exception
                 );
               }
-
+            }
-  /**
+          });
-   * Get a database instance for a specific firebase app instance
+      }
-   *
+    });
-   * @param appName
-   * @return
-   */
-  static FirebaseFirestore getFirestoreForApp(String appName) {
-    FirebaseApp firebaseApp = FirebaseApp.getInstance(appName);
-    return FirebaseFirestore.getInstance(firebaseApp);
   }
 
   /**
    * Get a collection reference for a specific app and path
    *
-   * @param appName
+   * @param appName appName
-   * @param filters
+   * @param filters filters
-   * @param orders
+   * @param orders  orders
-   * @param options
+   * @param options options
    * @param path    @return
    */
-  private RNFirebaseFirestoreCollectionReference getCollectionForAppPath(String appName, String path,
+  private RNFirebaseFirestoreCollectionReference getCollectionForAppPath(
+    String appName, String path,
     ReadableArray filters,
     ReadableArray orders,
-                                                                         ReadableMap options) {
+    ReadableMap options
-    return new RNFirebaseFirestoreCollectionReference(this.getReactApplicationContext(), appName, path, filters, orders, options);
+  ) {
+    return new RNFirebaseFirestoreCollectionReference(
+      this.getReactApplicationContext(),
+      appName,
+      path,
+      filters,
+      orders,
+      options
+    );
   }
 
   /**
    * Get a document reference for a specific app and path
    *
-   * @param appName
+   * @param appName appName
-   * @param path
+   * @param path    path
-   * @return
+   * @return RNFirebaseFirestoreDocumentReference
    */
   private RNFirebaseFirestoreDocumentReference getDocumentForAppPath(String appName, String path) {
-    return new RNFirebaseFirestoreDocumentReference(this.getReactApplicationContext(), appName, path);
+    return new RNFirebaseFirestoreDocumentReference(
-  }
+      this.getReactApplicationContext(),
-
+      appName,
-  /**
+      path
-   * Convert as firebase DatabaseError instance into a writable map
+    );
-   * with the correct web-like error codes.
-   *
-   * @param nativeException
-   * @return
-   */
-  static WritableMap getJSError(FirebaseFirestoreException nativeException) {
-    WritableMap errorMap = Arguments.createMap();
-    errorMap.putInt("nativeErrorCode", nativeException.getCode().value());
-    errorMap.putString("nativeErrorMessage", nativeException.getMessage());
-
-    String code;
-    String message;
-    String service = "Firestore";
-
-    // TODO: Proper error mappings
-    switch (nativeException.getCode()) {
-      case OK:
-        code = ErrorUtils.getCodeWithService(service, "ok");
-        message = ErrorUtils.getMessageWithService("Ok.", service, code);
-        break;
-      case CANCELLED:
-        code = ErrorUtils.getCodeWithService(service, "cancelled");
-        message = ErrorUtils.getMessageWithService("The operation was cancelled.", service, code);
-        break;
-      case UNKNOWN:
-        code = ErrorUtils.getCodeWithService(service, "unknown");
-        message = ErrorUtils.getMessageWithService("Unknown error or an error from a different error domain.", service, code);
-        break;
-      case INVALID_ARGUMENT:
-        code = ErrorUtils.getCodeWithService(service, "invalid-argument");
-        message = ErrorUtils.getMessageWithService("Client specified an invalid argument.", service, code);
-        break;
-      case DEADLINE_EXCEEDED:
-        code = ErrorUtils.getCodeWithService(service, "deadline-exceeded");
-        message = ErrorUtils.getMessageWithService("Deadline expired before operation could complete.", service, code);
-        break;
-      case NOT_FOUND:
-        code = ErrorUtils.getCodeWithService(service, "not-found");
-        message = ErrorUtils.getMessageWithService("Some requested document was not found.", service, code);
-        break;
-      case ALREADY_EXISTS:
-        code = ErrorUtils.getCodeWithService(service, "already-exists");
-        message = ErrorUtils.getMessageWithService("Some document that we attempted to create already exists.", service, code);
-        break;
-      case PERMISSION_DENIED:
-        code = ErrorUtils.getCodeWithService(service, "permission-denied");
-        message = ErrorUtils.getMessageWithService("The caller does not have permission to execute the specified operation.", service, code);
-        break;
-      case RESOURCE_EXHAUSTED:
-        code = ErrorUtils.getCodeWithService(service, "resource-exhausted");
-        message = ErrorUtils.getMessageWithService("Some resource has been exhausted, perhaps a per-user quota, or perhaps the entire file system is out of space.", service, code);
-        break;
-      case FAILED_PRECONDITION:
-        code = ErrorUtils.getCodeWithService(service, "failed-precondition");
-        message = ErrorUtils.getMessageWithService("Operation was rejected because the system is not in a state required for the operation`s execution.", service, code);
-        break;
-      case ABORTED:
-        code = ErrorUtils.getCodeWithService(service, "aborted");
-        message = ErrorUtils.getMessageWithService("The operation was aborted, typically due to a concurrency issue like transaction aborts, etc.", service, code);
-        break;
-      case OUT_OF_RANGE:
-        code = ErrorUtils.getCodeWithService(service, "out-of-range");
-        message = ErrorUtils.getMessageWithService("Operation was attempted past the valid range.", service, code);
-        break;
-      case UNIMPLEMENTED:
-        code = ErrorUtils.getCodeWithService(service, "unimplemented");
-        message = ErrorUtils.getMessageWithService("Operation is not implemented or not supported/enabled.", service, code);
-        break;
-      case INTERNAL:
-        code = ErrorUtils.getCodeWithService(service, "internal");
-        message = ErrorUtils.getMessageWithService("Internal errors.", service, code);
-        break;
-      case UNAVAILABLE:
-        code = ErrorUtils.getCodeWithService(service, "unavailable");
-        message = ErrorUtils.getMessageWithService("The service is currently unavailable.", service, code);
-        break;
-      case DATA_LOSS:
-        code = ErrorUtils.getCodeWithService(service, "data-loss");
-        message = ErrorUtils.getMessageWithService("Unrecoverable data loss or corruption.", service, code);
-        break;
-      case UNAUTHENTICATED:
-        code = ErrorUtils.getCodeWithService(service, "unauthenticated");
-        message = ErrorUtils.getMessageWithService("The request does not have valid authentication credentials for the operation.", service, code);
-        break;
-      default:
-        code = ErrorUtils.getCodeWithService(service, "unknown");
-        message = ErrorUtils.getMessageWithService("An unknown error occurred.", service, code);
-    }
-
-    errorMap.putString("code", code);
-    errorMap.putString("message", message);
-    return errorMap;
   }
 
   /**

android/src/main/java/io/invertase/firebase/firestore/RNFirebaseFirestoreCollectionReference.java

@@ -1,6 +1,7 @@
 package io.invertase.firebase.firestore;
 
 
+import android.annotation.SuppressLint;
 import android.support.annotation.NonNull;
 import android.util.Log;
 
@@ -22,28 +23,32 @@ import com.google.firebase.firestore.Query;
 import com.google.firebase.firestore.QuerySnapshot;
 import com.google.firebase.firestore.Source;
 
-import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 import io.invertase.firebase.Utils;
 
-public class RNFirebaseFirestoreCollectionReference {
+class RNFirebaseFirestoreCollectionReference {
   private static final String TAG = "RNFSCollectionReference";
   private static Map<String, ListenerRegistration> collectionSnapshotListeners = new HashMap<>();
 
-  private final String appName;
   private final String path;
-  private final ReadableArray filters;
-  private final ReadableArray orders;
-  private final ReadableMap options;
   private final Query query;
+  private final String appName;
+  private final ReadableMap options;
+  private final ReadableArray orders;
+  private final ReadableArray filters;
   private ReactContext reactContext;
 
-  RNFirebaseFirestoreCollectionReference(ReactContext reactContext, String appName, String path,
+  RNFirebaseFirestoreCollectionReference(
-                                         ReadableArray filters, ReadableArray orders,
+    ReactContext reactContext,
-                                         ReadableMap options) {
+    String appName,
+    String path,
+    ReadableArray filters,
+    ReadableArray orders,
+    ReadableMap options
+  ) {
     this.appName = appName;
     this.path = path;
     this.filters = filters;
@@ -53,6 +58,13 @@ public class RNFirebaseFirestoreCollectionReference {
     this.reactContext = reactContext;
   }
 
+  static void offSnapshot(final String listenerId) {
+    ListenerRegistration listenerRegistration = collectionSnapshotListeners.remove(listenerId);
+    if (listenerRegistration != null) {
+      listenerRegistration.remove();
+    }
+  }
+
   void get(ReadableMap getOptions, final Promise promise) {
     Source source;
     if (getOptions != null && getOptions.hasKey("source")) {
@@ -67,29 +79,34 @@ public class RNFirebaseFirestoreCollectionReference {
     } else {
       source = Source.DEFAULT;
     }
+
+    @SuppressLint("StaticFieldLeak") final QuerySnapshotSerializeAsyncTask serializeAsyncTask = new QuerySnapshotSerializeAsyncTask(
+      reactContext, this
+    ) {
+      @Override
+      protected void onPostExecute(WritableMap writableMap) {
+        promise.resolve(writableMap);
+      }
+    };
+
     query.get(source).addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
       @Override
       public void onComplete(@NonNull Task<QuerySnapshot> task) {
         if (task.isSuccessful()) {
           Log.d(TAG, "get:onComplete:success");
-          WritableMap data = FirestoreSerialize.snapshotToWritableMap(task.getResult());
+          serializeAsyncTask.execute(task.getResult());
-          promise.resolve(data);
         } else {
           Log.e(TAG, "get:onComplete:failure", task.getException());
-          RNFirebaseFirestore.promiseRejectException(promise, (FirebaseFirestoreException)task.getException());
+          RNFirebaseFirestore.promiseRejectException(
+            promise,
+            (FirebaseFirestoreException) task.getException()
+          );
         }
       }
     });
   }
 
-  public static void offSnapshot(final String listenerId) {
+  void onSnapshot(final String listenerId, final ReadableMap queryListenOptions) {
-    ListenerRegistration listenerRegistration = collectionSnapshotListeners.remove(listenerId);
-    if (listenerRegistration != null) {
-      listenerRegistration.remove();
-    }
-  }
-
-  public void onSnapshot(final String listenerId, final ReadableMap queryListenOptions) {
     if (!collectionSnapshotListeners.containsKey(listenerId)) {
       final EventListener<QuerySnapshot> listener = new EventListener<QuerySnapshot>() {
         @Override
@@ -97,7 +114,8 @@ public class RNFirebaseFirestoreCollectionReference {
           if (exception == null) {
             handleQuerySnapshotEvent(listenerId, querySnapshot);
           } else {
-            ListenerRegistration listenerRegistration = collectionSnapshotListeners.remove(listenerId);
+            ListenerRegistration listenerRegistration = collectionSnapshotListeners.remove(
+              listenerId);
             if (listenerRegistration != null) {
               listenerRegistration.remove();
             }
@@ -115,7 +133,10 @@ public class RNFirebaseFirestoreCollectionReference {
         metadataChanges = MetadataChanges.EXCLUDE;
       }
 
-      ListenerRegistration listenerRegistration = this.query.addSnapshotListener(metadataChanges, listener);
+      ListenerRegistration listenerRegistration = this.query.addSnapshotListener(
+        metadataChanges,
+        listener
+      );
       collectionSnapshotListeners.put(listenerId, listenerRegistration);
     }
   }
@@ -170,7 +191,7 @@ public class RNFirebaseFirestoreCollectionReference {
       } else {
         ReadableArray fieldPathElements = fieldPathMap.getArray("elements");
         String[] fieldPathArray = new String[fieldPathElements.size()];
-        for (int j=0; j<fieldPathElements.size(); j++) {
+        for (int j = 0; j < fieldPathElements.size(); j++) {
           fieldPathArray[j] = fieldPathElements.getString(j);
         }
         FieldPath fieldPath = FieldPath.of(fieldPathArray);
@@ -202,13 +223,13 @@ public class RNFirebaseFirestoreCollectionReference {
       Map<String, Object> order = (Map) o;
       String direction = (String) order.get("direction");
       Map<String, Object> fieldPathMap = (Map) order.get("fieldPath");
-      String fieldPathType = (String)fieldPathMap.get("type");
+      String fieldPathType = (String) fieldPathMap.get("type");
 
       if (fieldPathType.equals("string")) {
-        String fieldPath = (String)fieldPathMap.get("string");
+        String fieldPath = (String) fieldPathMap.get("string");
         query = query.orderBy(fieldPath, Query.Direction.valueOf(direction));
       } else {
-        List<String> fieldPathElements = (List)fieldPathMap.get("elements");
+        List<String> fieldPathElements = (List) fieldPathMap.get("elements");
         FieldPath fieldPath = FieldPath.of(fieldPathElements.toArray(new String[fieldPathElements.size()]));
         query = query.orderBy(fieldPath, Query.Direction.valueOf(direction));
       }
@@ -218,57 +239,79 @@ public class RNFirebaseFirestoreCollectionReference {
 
   private Query applyOptions(FirebaseFirestore firestore, Query query) {
     if (options.hasKey("endAt")) {
-      List<Object> endAtList = FirestoreSerialize.parseReadableArray(firestore, options.getArray("endAt"));
+      List<Object> endAtList = FirestoreSerialize.parseReadableArray(
+        firestore,
+        options.getArray("endAt")
+      );
       query = query.endAt(endAtList.toArray());
     }
+
     if (options.hasKey("endBefore")) {
-      List<Object> endBeforeList = FirestoreSerialize.parseReadableArray(firestore, options.getArray("endBefore"));
+      List<Object> endBeforeList = FirestoreSerialize.parseReadableArray(
+        firestore,
+        options.getArray("endBefore")
+      );
       query = query.endBefore(endBeforeList.toArray());
     }
+
     if (options.hasKey("limit")) {
       int limit = options.getInt("limit");
       query = query.limit(limit);
     }
-    if (options.hasKey("offset")) {
+//    if (options.hasKey("offset")) {
     // Android doesn't support offset
-    }
+//    }
-    if (options.hasKey("selectFields")) {
+//    if (options.hasKey("selectFields")) {
     // Android doesn't support selectFields
-    }
+//    }
     if (options.hasKey("startAfter")) {
-      List<Object> startAfterList= FirestoreSerialize.parseReadableArray(firestore, options.getArray("startAfter"));
+      List<Object> startAfterList = FirestoreSerialize.parseReadableArray(
+        firestore,
+        options.getArray("startAfter")
+      );
       query = query.startAfter(startAfterList.toArray());
     }
+
     if (options.hasKey("startAt")) {
-      List<Object> startAtList= FirestoreSerialize.parseReadableArray(firestore, options.getArray("startAt"));
+      List<Object> startAtList = FirestoreSerialize.parseReadableArray(
+        firestore,
+        options.getArray("startAt")
+      );
       query = query.startAt(startAtList.toArray());
     }
+
     return query;
   }
 
   /**
    * Handles documentSnapshot events.
    *
-   * @param listenerId
+   * @param listenerId    id
-   * @param querySnapshot
+   * @param querySnapshot snapshot
    */
-  private void handleQuerySnapshotEvent(String listenerId, QuerySnapshot querySnapshot) {
+  private void handleQuerySnapshotEvent(final String listenerId, QuerySnapshot querySnapshot) {
+    @SuppressLint("StaticFieldLeak") final QuerySnapshotSerializeAsyncTask serializeAsyncTask = new QuerySnapshotSerializeAsyncTask(
+      reactContext, this
+    ) {
+      @Override
+      protected void onPostExecute(WritableMap writableMap) {
         WritableMap event = Arguments.createMap();
-    WritableMap data = FirestoreSerialize.snapshotToWritableMap(querySnapshot);
-
-    event.putString("appName", appName);
         event.putString("path", path);
+        event.putString("appName", appName);
         event.putString("listenerId", listenerId);
-    event.putMap("querySnapshot", data);
+        event.putMap("querySnapshot", writableMap);
-
         Utils.sendEvent(reactContext, "firestore_collection_sync_event", event);
       }
+    };
+
+    serializeAsyncTask.execute(querySnapshot);
+  }
 
   /**
    * Handles a documentSnapshot error event
    *
-   * @param listenerId
+   * @param listenerId id
-   * @param exception
+   * @param exception  exception
    */
   private void handleQuerySnapshotError(String listenerId, FirebaseFirestoreException exception) {
     WritableMap event = Arguments.createMap();

android/src/main/java/io/invertase/firebase/firestore/RNFirebaseFirestoreDocumentReference.java

@@ -1,5 +1,6 @@
 package io.invertase.firebase.firestore;
 
+import android.annotation.SuppressLint;
 import android.support.annotation.NonNull;
 import android.util.Log;
 
@@ -31,17 +32,24 @@ public class RNFirebaseFirestoreDocumentReference {
 
   private final String appName;
   private final String path;
-  private ReactContext reactContext;
   private final DocumentReference ref;
+  private ReactContext reactContext;
 
   RNFirebaseFirestoreDocumentReference(ReactContext reactContext, String appName, String path) {
-    this.appName = appName;
     this.path = path;
+    this.appName = appName;
     this.reactContext = reactContext;
     this.ref = RNFirebaseFirestore.getFirestoreForApp(appName).document(path);
   }
 
-  public void delete(final Promise promise) {
+  static void offSnapshot(final String listenerId) {
+    ListenerRegistration listenerRegistration = documentSnapshotListeners.remove(listenerId);
+    if (listenerRegistration != null) {
+      listenerRegistration.remove();
+    }
+  }
+
+  void delete(final Promise promise) {
     this.ref.delete().addOnCompleteListener(new OnCompleteListener<Void>() {
       @Override
       public void onComplete(@NonNull Task<Void> task) {
@@ -50,7 +58,10 @@ public class RNFirebaseFirestoreDocumentReference {
           promise.resolve(null);
         } else {
           Log.e(TAG, "delete:onComplete:failure", task.getException());
-          RNFirebaseFirestore.promiseRejectException(promise, (FirebaseFirestoreException)task.getException());
+          RNFirebaseFirestore.promiseRejectException(
+            promise,
+            (FirebaseFirestoreException) task.getException()
+          );
         }
       }
     });
@@ -58,6 +69,7 @@ public class RNFirebaseFirestoreDocumentReference {
 
   void get(final ReadableMap getOptions, final Promise promise) {
     Source source;
+
     if (getOptions != null && getOptions.hasKey("source")) {
       String optionsSource = getOptions.getString("source");
       if ("server".equals(optionsSource)) {
@@ -70,45 +82,57 @@ public class RNFirebaseFirestoreDocumentReference {
     } else {
       source = Source.DEFAULT;
     }
+
+    @SuppressLint("StaticFieldLeak") final DocumentSnapshotSerializeAsyncTask serializeAsyncTask = new DocumentSnapshotSerializeAsyncTask(
+      reactContext, this
+    ) {
+      @Override
+      protected void onPostExecute(WritableMap writableMap) {
+        promise.resolve(writableMap);
+      }
+    };
+
     this.ref.get(source).addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
       @Override
       public void onComplete(@NonNull Task<DocumentSnapshot> task) {
         if (task.isSuccessful()) {
           Log.d(TAG, "get:onComplete:success");
-          WritableMap data = FirestoreSerialize.snapshotToWritableMap(task.getResult());
+          serializeAsyncTask.execute(task.getResult());
-          promise.resolve(data);
         } else {
           Log.e(TAG, "get:onComplete:failure", task.getException());
-          RNFirebaseFirestore.promiseRejectException(promise, (FirebaseFirestoreException)task.getException());
+          RNFirebaseFirestore.promiseRejectException(
+            promise,
+            (FirebaseFirestoreException) task.getException()
+          );
         }
       }
     });
   }
 
-  public static void offSnapshot(final String listenerId) {
+  void onSnapshot(final String listenerId, final ReadableMap docListenOptions) {
-    ListenerRegistration listenerRegistration = documentSnapshotListeners.remove(listenerId);
-    if (listenerRegistration != null) {
-      listenerRegistration.remove();
-    }
-  }
-
-  public void onSnapshot(final String listenerId, final ReadableMap docListenOptions) {
     if (!documentSnapshotListeners.containsKey(listenerId)) {
       final EventListener<DocumentSnapshot> listener = new EventListener<DocumentSnapshot>() {
         @Override
-        public void onEvent(DocumentSnapshot documentSnapshot, FirebaseFirestoreException exception) {
+        public void onEvent(
+          DocumentSnapshot documentSnapshot,
+          FirebaseFirestoreException exception
+        ) {
           if (exception == null) {
             handleDocumentSnapshotEvent(listenerId, documentSnapshot);
           } else {
             ListenerRegistration listenerRegistration = documentSnapshotListeners.remove(listenerId);
+
             if (listenerRegistration != null) {
               listenerRegistration.remove();
             }
+
             handleDocumentSnapshotError(listenerId, exception);
           }
         }
       };
+
       MetadataChanges metadataChanges;
+
       if (docListenOptions != null
         && docListenOptions.hasKey("includeMetadataChanges")
         && docListenOptions.getBoolean("includeMetadataChanges")) {
@@ -116,19 +140,30 @@ public class RNFirebaseFirestoreDocumentReference {
       } else {
         metadataChanges = MetadataChanges.EXCLUDE;
       }
-      ListenerRegistration listenerRegistration = this.ref.addSnapshotListener(metadataChanges, listener);
+
+      ListenerRegistration listenerRegistration = this.ref.addSnapshotListener(
+        metadataChanges,
+        listener
+      );
+
       documentSnapshotListeners.put(listenerId, listenerRegistration);
     }
   }
 
   public void set(final ReadableMap data, final ReadableMap options, final Promise promise) {
-    Map<String, Object> map = FirestoreSerialize.parseReadableMap(RNFirebaseFirestore.getFirestoreForApp(appName), data);
     Task<Void> task;
+
+    Map<String, Object> map = FirestoreSerialize.parseReadableMap(
+      RNFirebaseFirestore.getFirestoreForApp(appName),
+      data
+    );
+
     if (options != null && options.hasKey("merge") && options.getBoolean("merge")) {
       task = this.ref.set(map, SetOptions.merge());
     } else {
       task = this.ref.set(map);
     }
+
     task.addOnCompleteListener(new OnCompleteListener<Void>() {
       @Override
       public void onComplete(@NonNull Task<Void> task) {
@@ -137,14 +172,21 @@ public class RNFirebaseFirestoreDocumentReference {
           promise.resolve(null);
         } else {
           Log.e(TAG, "set:onComplete:failure", task.getException());
-          RNFirebaseFirestore.promiseRejectException(promise, (FirebaseFirestoreException)task.getException());
+          RNFirebaseFirestore.promiseRejectException(
+            promise,
+            (FirebaseFirestoreException) task.getException()
+          );
         }
       }
     });
   }
 
-  public void update(final ReadableMap data, final Promise promise) {
+  void update(final ReadableMap data, final Promise promise) {
-    Map<String, Object> map = FirestoreSerialize.parseReadableMap(RNFirebaseFirestore.getFirestoreForApp(appName), data);
+    Map<String, Object> map = FirestoreSerialize.parseReadableMap(
+      RNFirebaseFirestore.getFirestoreForApp(appName),
+      data
+    );
+
     this.ref.update(map).addOnCompleteListener(new OnCompleteListener<Void>() {
       @Override
       public void onComplete(@NonNull Task<Void> task) {
@@ -153,7 +195,10 @@ public class RNFirebaseFirestoreDocumentReference {
           promise.resolve(null);
         } else {
           Log.e(TAG, "update:onComplete:failure", task.getException());
-          RNFirebaseFirestore.promiseRejectException(promise, (FirebaseFirestoreException)task.getException());
+          RNFirebaseFirestore.promiseRejectException(
+            promise,
+            (FirebaseFirestoreException) task.getException()
+          );
         }
       }
     });
@@ -163,7 +208,7 @@ public class RNFirebaseFirestoreDocumentReference {
    * INTERNALS/UTILS
    */
 
-  public DocumentReference getRef() {
+  DocumentReference getRef() {
     return ref;
   }
 
@@ -174,32 +219,44 @@ public class RNFirebaseFirestoreDocumentReference {
   /**
    * Handles documentSnapshot events.
    *
-   * @param listenerId
+   * @param listenerId       id
-   * @param documentSnapshot
+   * @param documentSnapshot snapshot
    */
-  private void handleDocumentSnapshotEvent(String listenerId, DocumentSnapshot documentSnapshot) {
+  private void handleDocumentSnapshotEvent(
+    final String listenerId,
+    DocumentSnapshot documentSnapshot
+  ) {
+    @SuppressLint("StaticFieldLeak") final DocumentSnapshotSerializeAsyncTask serializeAsyncTask = new DocumentSnapshotSerializeAsyncTask(
+      reactContext, this
+    ) {
+      @Override
+      protected void onPostExecute(WritableMap writableMap) {
         WritableMap event = Arguments.createMap();
-    WritableMap data = FirestoreSerialize.snapshotToWritableMap(documentSnapshot);
-
-    event.putString("appName", appName);
         event.putString("path", path);
+        event.putString("appName", appName);
         event.putString("listenerId", listenerId);
-    event.putMap("documentSnapshot", data);
+        event.putMap("documentSnapshot", writableMap);
-
         Utils.sendEvent(reactContext, "firestore_document_sync_event", event);
       }
+    };
+
+    serializeAsyncTask.execute(documentSnapshot);
+  }
 
   /**
    * Handles a documentSnapshot error event
    *
-   * @param listenerId
+   * @param listenerId id
-   * @param exception
+   * @param exception  exception
    */
-  private void handleDocumentSnapshotError(String listenerId, FirebaseFirestoreException exception) {
+  private void handleDocumentSnapshotError(
+    String listenerId,
+    FirebaseFirestoreException exception
+  ) {
     WritableMap event = Arguments.createMap();
 
-    event.putString("appName", appName);
     event.putString("path", path);
+    event.putString("appName", appName);
     event.putString("listenerId", listenerId);
     event.putMap("error", RNFirebaseFirestore.getJSError(exception));
 

android/src/main/java/io/invertase/firebase/firestore/RNFirebaseFirestorePackage.java

@@ -1,7 +1,6 @@
 package io.invertase.firebase.firestore;
 
 import com.facebook.react.ReactPackage;
-import com.facebook.react.bridge.JavaScriptModule;
 import com.facebook.react.bridge.NativeModule;
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.uimanager.UIManagerModule;
@@ -29,7 +28,7 @@ public class RNFirebaseFirestorePackage implements ReactPackage {
   }
 
   /**
-   * @param reactContext
+   * @param reactContext reactContext
    * @return a list of view managers that should be registered with {@link UIManagerModule}
    */
   @Override

android/src/main/java/io/invertase/firebase/firestore/RNFirebaseFirestoreTransactionHandler.java

@@ -17,17 +17,16 @@ import javax.annotation.Nullable;
 
 
 class RNFirebaseFirestoreTransactionHandler {
+  private final ReentrantLock lock;
+  private final Condition condition;
+  boolean aborted = false;
+  boolean timeout = false;
   private String appName;
   private long timeoutAt;
   private int transactionId;
-  private final ReentrantLock lock;
-  private final Condition condition;
   private ReadableArray commandBuffer;
   private Transaction firestoreTransaction;
 
-  boolean aborted = false;
-  boolean timeout = false;
-
   RNFirebaseFirestoreTransactionHandler(String app, int id) {
     appName = app;
     transactionId = id;