How to use redux_persist when store is implemented using built_redux

[vishant-jaiswal]

I am getting following error while loading

E/flutter (26697): [ERROR:flutter/shell/common/shell.cc(184)] Dart Error: Unhandled exception: E/flutter (26697): SerializationException: On load: NoSuchMethodError: The getter 'first' was called on null. E/flutter (26697): Receiver: null E/flutter (26697): Tried calling: first E/flutter (26697): #0 Persistor.load (package:redux_persist/src/persistor.dart:131:7) E/flutter (26697): E/flutter (26697): #1 main (package:samco_app/main.dart:39:40) E/flutter (26697): E/flutter (26697): #2 _startIsolate. (dart:isolate/runtime/libisolate_patch.dart:289:19) E/flutter (26697): #3 _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)

[Knupper]

i get a similar error when i start the app the first time. then persistor.load() throws a error. i fixed it with the following code:

try { initialState = await persistor.load(); } catch (e) { // ; }

here is my old code:

` final persistor = Persistor( storage: FlutterStorage(), serializer: JsonSerializer(AppState.fromJson), debug: true, );

final initialState = await persistor.load();

final store = Store( syncReducerAppState, initialState: initialState ?? AppState(entries: [], myObject: {}), middleware: [persistor.createMiddleware(), asyncReducerAppState], );`

here the error message with debug mode on:

`I/flutter (16048): Persistor debug: Starting load...

I/flutter (16048): Persistor debug: Loading from storage

I/flutter (16048): Persistor debug: Running load raw transformations

I/flutter (16048): Persistor debug: Deserializing

I/flutter (16048): Persistor debug: Error while loading: SerializationException: On load: NoSuchMethodError: The method '[]' was called on null.

I/flutter (16048): Receiver: null

I/flutter (16048): Tried calling:

E/flutter (16048): [ERROR:flutter/shell/common/shell.cc(184)] Dart Error: Unhandled exception:

E/flutter (16048): SerializationException: On load: NoSuchMethodError: The method '[]' was called on null.

E/flutter (16048): Receiver: null

E/flutter (16048): Tried calling:

E/flutter (16048): #0 Persistor.load (package:redux_persist/src/persistor.dart:131:7)

E/flutter (16048):

E/flutter (16048): #1 main (package:test/main.dart:30:40)

E/flutter (16048):

E/flutter (16048): #2 _startIsolate.

(dart:isolate/runtime/libisolate_patch.dart:289:19)

E/flutter (16048): #3 _RawReceivePortImpl._handleMessage

(dart:isolate/runtime/libisolate_patch.dart:171:12)`

[Cretezy]

The error is thrown from you serializer, as seen with SerializationException. Are you calling .first in your serializer?

Don't forget that serializer must handle null cases. Data coming in/out must be able to accept null or empty data, and fallback gracefully.