type 'List<dynamic>' is not a subtype of type 'List<String>'

[sahil311289]

Restarted app in 2,687ms.
I/ViewRootImpl(20672): ViewRoot's Touch Event : ACTION_DOWN
I/flutter (20672): _MyAppState.activateSpeechRecognizer... 
I/ViewRootImpl(20672): ViewRoot's Touch Event : ACTION_UP
D/SpeechRecognitionPlugin(20672): Current Locale : en_GB
I/flutter (20672): _platformCallHandler call speech.onCurrentLocale en_GB
I/ViewRootImpl(20672): ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl(20672): ViewRoot's Touch Event : ACTION_UP
I/ViewRootImpl(20672): ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl(20672): ViewRoot's Touch Event : ACTION_UP
I/flutter (20672): Dislike
I/flutter (20672): ══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
I/flutter (20672): The following assertion was thrown while handling a gesture:
I/flutter (20672): type 'List<dynamic>' is not a subtype of type 'List<String>'
I/flutter (20672): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter (20672): more information in this error message to help you determine and fix the underlying cause.
I/flutter (20672): In either case, please report this assertion by filing a bug on GitHub:
I/flutter (20672):   https://github.com/flutter/flutter/issues/new
I/flutter (20672): When the exception was thrown, this was the stack:
I/flutter (20672): #0      _ChatListTileItemState.build.<anonymous closure> (file:///Users/sahil/IdeaProjects/gabhub_anonym_text/lib/live_chat_tab_base.dart:429:85)
I/flutter (20672): #1      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
I/flutter (20672): #2      TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:161:9)
I/flutter (20672): #3      TapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:123:7)
I/flutter (20672): #4      GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
I/flutter (20672): #5      _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:147:20)
I/flutter (20672): #6      _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:121:22)
I/flutter (20672): #7      _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:101:7)
I/flutter (20672): #8      _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:64:7)
I/flutter (20672): #9      _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:48:7)
I/flutter (20672): #10     _invoke1 (dart:ui/hooks.dart:134:13)
I/flutter (20672): #11     _dispatchPointerDataPacket (dart:ui/hooks.dart:91:5)
I/flutter (20672): Handler: onTap
I/flutter (20672): Recognizer:
I/flutter (20672):   TapGestureRecognizer#cf6d7(debugOwner: GestureDetector, state: ready, won arena, finalPosition:
I/flutter (20672):   Offset(125.9, 380.8), sent tap down)
I/flutter (20672): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/ViewRootImpl(20672): ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl(20672): ViewRoot's Touch Event : ACTION_UP

[sahil311289]

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel beta, v0.5.1, on Mac OS X 10.13.5 17F77, locale en-IN)
[!] Android toolchain - develop for Android devices (Android SDK 28.0.0-rc1)
    ✗ Android license status unknown.
[✓] iOS toolchain - develop for iOS devices (Xcode 9.4.1)
[✓] Android Studio (version 3.1)
[✓] IntelliJ IDEA Community Edition (version 2018.1.5)
[✓] VS Code (version 1.23.1)
[✓] Connected devices (1 available)

! Doctor found issues in 1 category.

[sahil311289]

Assigning a List type to an actual List gives an exception.

type 'List<dynamic>' is not a subtype of type 'List<String>'
Handler: 

[jonahwilliams]

@sahil311289 this looks like a type error in your code, maybe see sound dart.

For example, you might be doing something like this:

List xs = ["asd", "dss"]; // list<dynamic>
taksesAListOfStrings(xs); // error List<dynamic> is not a subtype of List<String>

[sahil311289]

This is what I'm trying to do:

print('Like');
update(widget.document.reference, LiveChat.fromMap(widget.document.data).like, 'sahil');

In LiveChat class, I'm trying to encode/decode:

import 'dart:collection';

class LiveChat {
  String message;
  DateTime timestamp;
  String university;
  String email;
  dynamic like = new List<String>();
  dynamic dislike = new List<String>();
  dynamic laugh = new List<String>();
  dynamic cry = new List<String>();
  dynamic angry = new List<String>();

  LiveChat(this.message, this.timestamp, this.university, this.email, this.like,
      this.dislike, this.laugh, this.cry, this.angry);

  LiveChat.fromMap(Map<String, dynamic> data) {
    this.message = data['message'];
    this.timestamp = data['timestamp'];
    this.university = data['university'];
    this.email = data['email'];
    this.like = data['like'];
    this.dislike = data['dislike'];
    this.laugh = data['laugh'];
    this.cry = data['cry'];
    this.angry = data['angry'];
  }

  Map<String, dynamic> toMap() => {
        'message': this.message,
        'timestamp': this.timestamp,
        'university': this.university,
        'email': this.email,
        'like': this.like,
        'dislike': this.dislike,
        'laugh': this.laugh,
        'cry': this.cry,
        'angry': this.angry
      };
}

Even though data['like'] is of type _List, it gives an exception if I initialize 'like' like the following:

List<String> like = new List<String>();

Initializing the list as dynamic doesn't give exception. But adding to it at a later point surely gives one.

Future<bool> update(DocumentReference reference, dynamic likes, String s) async {
    final TransactionHandler updateTransaction = (Transaction transaction) async {

      final DocumentSnapshot freshSnap = await transaction.get(reference);
      Map<String, dynamic> data = new Map();
      likes.add('sahil');   // Exception here

      data.putIfAbsent('like', () => likes);
      await freshSnap.reference.setData(data, merge: true);
      return {'result': true};
    };
    return Firestore.instance.runTransaction(updateTransaction).then((r) => r['result']).catchError((e) {
      print('GabHub dart error: $e');
      return false;
    });
  }

I'm trying to add to an existing list but it fails. The only workaround I have is, to convert the dynamic type to string, split it and then add it to the list. But the whole point of decoding is lost.

[jonahwilliams]

The problem is your fromMap constructor is reading from a Map<String, dynamic>, so I bet that all of the lists in that map are actually List<dynamic> or just dynamic. Try doing this instead:

List<String> likes;

LiveChat.fromMap(Map<String, dynamic> data) {
  likes = data['likes'].cast<String>();
}

[sahil311289]

That fixed the type casting error.
Here's another one:

Future<bool> update(DocumentReference reference, List<String> likes, String s) async {
    final TransactionHandler updateTransaction = (Transaction transaction) async {

      final DocumentSnapshot freshSnap = await transaction.get(reference);
      Map<String, List<String>> data = new Map();
      likes.add(s);        // Exception

      data.putIfAbsent('like', () => likes);
      await freshSnap.reference.setData(data, merge: true);
      return {'result': true};
    };
    return Firestore.instance.runTransaction(updateTransaction).then((r) => r['result']).catchError((e) {
      print('GabHub dart error: $e');
      return false;
    });
  }

likes already has 2 String values. So no initailization related issues. I hope it's not a silly error.

[jonahwilliams]

What is the exception there?

[sahil311289]

Launching lib/main.dart on LG D802 in debug mode...
Initializing gradle...
Resolving dependencies...
Running 'gradlew assembleDebug'...
Configuration 'compile' in project ':app' is deprecated. Use 'implementation' instead.
registerResGeneratingTask is deprecated, use registerGeneratedFolders(FileCollection)
registerResGeneratingTask is deprecated, use registerGeneratedFolders(FileCollection)
registerResGeneratingTask is deprecated, use registerGeneratedFolders(FileCollection)
Warning: Missing asset in fonts for BadScript
Warning: Missing asset in fonts for Roboto
Warning: Missing asset in fonts for Roboto
Built build/app/outputs/apk/debug/app-debug.apk.
Installing build/app/outputs/apk/app.apk...
I/FlutterActivityDelegate(13081): onResume setting current activity to this
Warning: Missing asset in fonts for BadScript
Warning: Missing asset in fonts for Roboto
Warning: Missing asset in fonts for Roboto
Syncing files to device LG D802...
I/flutter (13081): _MyAppState.activateSpeechRecognizer... 
D/SpeechRecognitionPlugin(13081): Current Locale : en_GB
W/ResourcesManager(13081): Asset path '/system/framework/com.android.media.remotedisplay.jar' does not exist or contains no resources.
W/ResourcesManager(13081): Asset path '/system/framework/com.android.location.provider.jar' does not exist or contains no resources.
V/NativeCrypto(13081): Registering com/google/android/gms/org/conscrypt/NativeCrypto's 280 native methods...
I/art     (13081): Rejecting re-init on previously-failed class java.lang.Class<com.google.android.gms.org.conscrypt.Java7ExtendedSSLSession>
I/art     (13081): Rejecting re-init on previously-failed class java.lang.Class<com.google.android.gms.org.conscrypt.Java7ExtendedSSLSession>
I/art     (13081): Rejecting re-init on previously-failed class java.lang.Class<com.google.android.gms.org.conscrypt.Java8ExtendedSSLSession>
I/art     (13081): Rejecting re-init on previously-failed class java.lang.Class<com.google.android.gms.org.conscrypt.Java8ExtendedSSLSession>
W/System  (13081): Could not create com.google.android.gms.org.conscrypt.OpenSSLSocketFactoryImpl with ClassLoader dalvik.system.PathClassLoader[DexPathList[[zip file "/data/app/chat.gabhub.Chat.gabhubanonymtext-1/base.apk"],nativeLibraryDirectories=[/data/app/chat.gabhub.Chat.gabhubanonymtext-1/lib/arm, /vendor/lib, /system/lib]]]: com.google.android.gms.org.conscrypt.OpenSSLSocketFactoryImpl
I/ProviderInstaller(13081): Installed default security provider GmsCore_OpenSSL
D/libc-netbsd(13081): [getaddrinfo]: hostname=xxxxx; servname=(null); cache_mode=(null), netid=0; mark=0
D/libc-netbsd(13081): [getaddrinfo]: ai_addrlen=0; ai_canonname=xxxxx; ai_flags=4; ai_family=0
D/libc-netbsd(13081): [getaddrinfo]: hostname=xxxxx; servname=(null); cache_mode=(null), netid=0; mark=0
D/libc-netbsd(13081): [getaddrinfo]: ai_addrlen=0; ai_canonname=xxxxx; ai_flags=1024; ai_family=0
I/System.out(13081): propertyValue:false
D/libc-netbsd(13081): [getaddrinfo]: hostname=xxxxx; servname=(null); cache_mode=(null), netid=0; mark=0
D/libc-netbsd(13081): [getaddrinfo]: ai_addrlen=0; ai_canonname=xxxxx; ai_flags=4; ai_family=0
I/flutter (13081): _platformCallHandler call speech.onCurrentLocale en_GB
I/ViewRootImpl(13081): ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl(13081): ViewRoot's Touch Event : ACTION_UP
I/ViewRootImpl(13081): ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl(13081): ViewRoot's Touch Event : ACTION_UP
I/flutter (13081): Like
E/flutter (13081): [ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception:
E/flutter (13081): type 'Future<dynamic>' is not a subtype of type 'FutureOr<bool>'
E/flutter (13081): #0      _ChatListTileItemState.update (file:///Users/sahil/IdeaProjects/gabhub_anonym_text/lib/live_chat_tab_base.dart:554:90)
E/flutter (13081): <asynchronous suspension>
E/flutter (13081): #1      _ChatListTileItemState.build.<anonymous closure> (file:///Users/sahil/IdeaProjects/gabhub_anonym_text/lib/live_chat_tab_base.dart:429:31)
E/flutter (13081): #2      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
E/flutter (13081): #3      TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:161:9)
E/flutter (13081): #4      TapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:123:7)
E/flutter (13081): #5      GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
E/flutter (13081): #6      _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:147:20)
E/flutter (13081): #7      _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:121:22)
E/flutter (13081): #8      _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:101:7)
E/flutter (13081): #9      _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:64:7)
E/flutter (13081): #10     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:48:7)
E/flutter (13081): #11     _invoke1 (dart:ui/hooks.dart:134:13)
E/flutter (13081): #12     _dispatchPointerDataPacket (dart:ui/hooks.dart:91:5)
I/flutter (13081): GabHub dart error: PlatformException(Error performing transaction, java.lang.Exception: Do transaction failed., null)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): Failed to handle method call result
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): java.lang.IllegalStateException: Task is already complete
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at com.google.android.gms.common.internal.Preconditions.checkState(Unknown Source)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at com.google.android.gms.tasks.zzu.zzdr(Unknown Source)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at com.google.android.gms.tasks.zzu.setException(Unknown Source)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at com.google.android.gms.tasks.TaskCompletionSource.setException(Unknown Source)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at io.flutter.plugins.firebase.cloudfirestore.CloudFirestorePlugin$3$1.error(CloudFirestorePlugin.java:290)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at io.flutter.plugin.common.MethodChannel$IncomingResultHandler.reply(MethodChannel.java:171)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at io.flutter.view.FlutterNativeView.handlePlatformMessageResponse(FlutterNativeView.java:187)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at android.os.MessageQueue.nativePollOnce(Native Method)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at android.os.MessageQueue.next(MessageQueue.java:143)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at android.os.Looper.loop(Looper.java:122)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at android.app.ActivityThread.main(ActivityThread.java:5349)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at java.lang.reflect.Method.invoke(Native Method)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at java.lang.reflect.Method.invoke(Method.java:372)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:908)
E/MethodChannel#plugins.flutter.io/cloud_firestore(13081): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:703)

[jonahwilliams]

Possibly related to #17663?

[sahil311289]

I had that same issue. Got it resolved by playing aorund with data.
The followong works perfectly fine:

Future<bool> update(DocumentReference reference, List<String> likes, String s) async {
    final TransactionHandler updateTransaction = (Transaction transaction) async {

      final DocumentSnapshot freshSnap = await transaction.get(reference);
      Map<String, List<String>> data = new Map();
//      likes.add(s);        // Exception

      List<String> names = new List<String>();
      names.add('Sahil');
      names.add('Jonahwilliams');

      data.putIfAbsent('like', () => names);
      await freshSnap.reference.setData(data, merge: true);
      return {'result': true};
    };
    return Firestore.instance.runTransaction(updateTransaction).then((r) => r['result']).catchError((e) {
      print('GabHub dart error: $e');
      return false;
    });
  }

But as soon as you introduce Firebase data, it starts giving issues.
Maybe it is related. I trust your judgement :)

[sahil311289]

Please notice the difference in the structures of 'likes' and 'names'. Perhaps casting like the following

this.like = data['like'].cast<String>();

is not the best option. Meanwhile, I'll make use of dynamic type, cast it to a String, split it and get the list data. That one would do until this issue gets resolved.

[sahil311289]

Future<bool> update(DocumentReference reference, dynamic likes, String s) async {
    final TransactionHandler updateTransaction = (Transaction transaction) async {

      final DocumentSnapshot freshSnap = await transaction.get(reference);
      Map<String, List<String>> data = new Map();

      String likesListString = likes.toString();
      likesListString = likesListString.substring(1, likesListString.length-1);
      List<String> likeList = likesListString.split(", ");

      data.putIfAbsent('like', () => likeList);
      await freshSnap.reference.setData(data, merge: true);
      return {'result': true};
    };
    return Firestore.instance.runTransaction(updateTransaction).then((r) => r['result']).catchError((e) {
      print('GabHub dart error: $e');
      return false;
    });
  }

I presumed this would work since I'm making use of pure List type. Guess what? I was wrong. @jonahwilliams: You were right. This is not a type casting issue alone. Here's the result:

Performing hot reload...
Reloaded 3 of 515 libraries in 1,964ms.
I/ViewRootImpl(16691): ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl(16691): ViewRoot's Touch Event : ACTION_UP
I/ViewRootImpl(16691): ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl(16691): ViewRoot's Touch Event : ACTION_UP
I/flutter (16691): Like
E/flutter (16691): [ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception:
E/flutter (16691): type 'Future<dynamic>' is not a subtype of type 'FutureOr<bool>'
E/flutter (16691): #0      _ChatListTileItemState.update (file:///Users/sahil/IdeaProjects/gabhub_anonym_text/lib/live_chat_tab_base.dart:557:90)
E/flutter (16691): <asynchronous suspension>
E/flutter (16691): #1      _ChatListTileItemState.build.<anonymous closure> (file:///Users/sahil/IdeaProjects/gabhub_anonym_text/lib/live_chat_tab_base.dart:429:31)
E/flutter (16691): #2      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
E/flutter (16691): #3      TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:161:9)
E/flutter (16691): #4      TapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:123:7)
E/flutter (16691): #5      GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
E/flutter (16691): #6      _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:147:20)
E/flutter (16691): #7      _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:121:22)
E/flutter (16691): #8      _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:101:7)
E/flutter (16691): #9      _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:64:7)
E/flutter (16691): #10     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:48:7)
E/flutter (16691): #11     _invoke1 (dart:ui/hooks.dart:134:13)
E/flutter (16691): #12     _dispatchPointerDataPacket (dart:ui/hooks.dart:91:5)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): Failed to handle method call result
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): java.lang.IllegalStateException: Task is already complete
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at com.google.android.gms.common.internal.Preconditions.checkState(Unknown Source)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at com.google.android.gms.tasks.zzu.zzdr(Unknown Source)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at com.google.android.gms.tasks.zzu.setResult(Unknown Source)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at com.google.android.gms.tasks.TaskCompletionSource.setResult(Unknown Source)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at io.flutter.plugins.firebase.cloudfirestore.CloudFirestorePlugin$3$1.success(CloudFirestorePlugin.java:283)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at io.flutter.plugin.common.MethodChannel$IncomingResultHandler.reply(MethodChannel.java:169)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at io.flutter.view.FlutterNativeView.handlePlatformMessageResponse(FlutterNativeView.java:187)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at android.os.MessageQueue.nativePollOnce(Native Method)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at android.os.MessageQueue.next(MessageQueue.java:143)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at android.os.Looper.loop(Looper.java:122)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at android.app.ActivityThread.main(ActivityThread.java:5349)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at java.lang.reflect.Method.invoke(Native Method)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at java.lang.reflect.Method.invoke(Method.java:372)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:908)
E/MethodChannel#plugins.flutter.io/cloud_firestore(16691): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:703)

[jonahwilliams]

runTransaction probably returns a Future<dynamic>, so you would need to update your code to actually return a Future<bool>.

Future<bool> update(DocumentReference reference, dynamic likes, String s) async {
  /* */
  try {
    final result = await Firestore.instance.runTransaction(updateTransaction);
    return true;
  }  catch (err) {
     return false;
  }
}

[zoechi]

I believe this issue is stale.

[unibeck]

I did what @jonahwilliams suggested with the cast<Type>() and it was working nicely for a while. Though I encountered an error where if the value for the key in the map was null (e.g. not found) and threw the following error:

I/flutter (17982): The method 'cast' was called on null.
I/flutter (17982): Receiver: null
I/flutter (17982): Tried calling: cast<DocumentReference>()

with the following code

Object.fromMap(Map<String, dynamic> map, {this.reference})
    : readBy = map['readBy'].cast<DocumentReference>();

---

To fix this you can make an ugly inline null check:

readBy = (map['readBy'] != null) ? map['readBy'].cast<DocumentReference>() : null

But the cleaner and more Dartful way of accomplishing this is with the null-aware ?. operator:

readBy = map['readBy']?.cast<DocumentReference>()

Leaving this slight improvement here encase anyone else comes across this issue.

[vivekanandasuggu]

My model class is like this

`import 'dart:convert';

List serviceLogsModelFromJson(String str) => new List.from(json.decode(str).map((x) => ServiceLogsModel.fromJson(x)));

String serviceLogsModelToJson(List data) => json.encode(new List.from(data.map((x) => x.toJson())));

class ServiceLogsModel {
String vitCasenumber;
String title;
DateTime createdon;
DateTime modifiedon;
String statuscodeODataCommunityDisplayV1FormattedValue;
int statecode;
String incidentid;
bool vitIsfilemandatory;
String customeridContact;
String vitFilesuploadedtosharepoint;
String vitJsondata;
int vitTypeofform;
bool vitReadstatus;

ServiceLogsModel({
this.vitCasenumber,
this.title,
this.createdon,
this.modifiedon,
this.statuscodeODataCommunityDisplayV1FormattedValue,
this.statecode,
this.incidentid,
this.vitIsfilemandatory,
this.customeridContact,
this.vitFilesuploadedtosharepoint,
this.vitJsondata,
this.vitTypeofform,
this.vitReadstatus,
});

factory ServiceLogsModel.fromJson(Map<String, dynamic> json) => new ServiceLogsModel(
vitCasenumber: json["vit_casenumber"],
title: json["title"],
createdon: DateTime.parse(json["createdon"]),
modifiedon: DateTime.parse(json["modifiedon"]),
statuscodeODataCommunityDisplayV1FormattedValue: json["statuscode@OData.Community.Display.V1.FormattedValue"],
statecode: json["statecode"],
incidentid: json["incidentid"],
vitIsfilemandatory: json["vit_isfilemandatory"],
customeridContact: json["customerid_contact"],
vitFilesuploadedtosharepoint: json["vit_filesuploadedtosharepoint"],
vitJsondata: json["vit_jsondata"],
vitTypeofform: json["vit_typeofform"],
vitReadstatus: json["vit_readstatus"],
);

Map<String, dynamic> toJson() => {
"vit_casenumber": vitCasenumber,
"title": title,
"createdon": createdon.toIso8601String(),
"modifiedon": modifiedon.toIso8601String(),
"statuscode@OData.Community.Display.V1.FormattedValue": statuscodeODataCommunityDisplayV1FormattedValue,
"statecode": statecode,
"incidentid": incidentid,
"vit_isfilemandatory": vitIsfilemandatory,
"customerid_contact": customeridContact,
"vit_filesuploadedtosharepoint": vitFilesuploadedtosharepoint,
"vit_jsondata": vitJsondata,
"vit_typeofform": vitTypeofform,
"vit_readstatus": vitReadstatus,
};
}
`

I am getting the response like this

[
{
"vit_casenumber": "CM1902849",
"title": "Request For Reference Letter",
"createdon": "2019-06-27T04:43:44Z",
"modifiedon": "2019-06-27T04:54:03Z",
"statuscode@OData.Community.Display.V1.FormattedValue": "New",
"statecode": 0,
"incidentid": "e7d38720-9698-e911-a855-000d3ae0a7f8",
"vit_isfilemandatory": false,
"customerid_contact": null,
"vit_filesuploadedtosharepoint": null,
"vit_jsondata": null,
"vit_typeofform": 2,
"vit_readstatus": true
},
{
"vit_casenumber": "CM1902848",
"title": "Request For Reference Letter",
"createdon": "2019-06-26T12:53:13Z",
"modifiedon": "2019-06-26T12:53:17Z",
"statuscode@OData.Community.Display.V1.FormattedValue": "New",
"statecode": 0,
"incidentid": "681bb658-1198-e911-a852-000d3ae0b82e",
"vit_isfilemandatory": false,
"customerid_contact": null,
"vit_filesuploadedtosharepoint": null,
"vit_jsondata": null,
"vit_typeofform": 2,
"vit_readstatus": false
}
]

when I am executing this line

json.decode(response.body);

I am getting this error

Unhandled Exception: type 'List' is not a subtype of type 'String'

Please help me to sort out the problem

[joao-rafael]

Got the same issue while trying to pass a list to the items property of the DorpdownMenu widget.

[Ashbuhrz]

The problem is your fromMap constructor is reading from a Map<String, dynamic>, so I bet that all of the lists in that map are actually List<dynamic> or just dynamic. Try doing this instead:

List<String> likes;

LiveChat.fromMap(Map<String, dynamic> data) {
  likes = data['likes'].cast<String>();
}

can you please help me with this also

     body: Container(
     child: Center(
      child: FutureBuilder(
        future:
            DefaultAssetBundle.of(context).loadString('jsons/data.json'),
        builder: (context, snapshot) {
          if (!snapshot.hasData) {
            return CircularProgressIndicator();
          }
          var myData = jsonDecode(snapshot.data);
          final welcome = welcomeFromJson(myData);

          print(myData.length);
          return ListView.builder(
            itemBuilder: (BuildContext context, int index) {
              return Card(
                  child: ListTile(
                title: Text(welcome[index]
                    .tableMenuList[index]
                    .categoryDishes[index]
                    .dishName),
              ));
            },
            itemCount: myData == null ? 0 : myData.length,
          );
        },
      ),
    ),
  ),

error : type 'List' is not a subtype of type 'String'

[mohit-solankee99]

@Ashbuhrz You should add mydata in List
with following code

List data;

var myData = jsonDecode(snapshot.data);
data=mydata[''];

and item count will be

itemCount: data == null ? 0 : data.length,

[mamedshahmaliyev]

just use: (yourlist as List).map((e) => e.toString()).toList();

[ella97]

class Product {
  int id;
  String name;
  String photo;
  int price;
  int discount;
  String productDetail;
  int quantity;

  toMap() {
    var map = Map<String, dynamic>();
    map['productId'] = id;
    map['productName'] = name;
    map['productPhoto'] = photo;
    map['productPrice'] = price;
    map['productDiscount'] = discount;
    map['productQuantity'] = quantity;
    return map;
  }

  
}

type 'List<dynamic>' is not a subtype of type 'List<String>'

please help

[Santosh1432]

My model class is like this

`import 'dart:convert';

List serviceLogsModelFromJson(String str) => new List.from(json.decode(str).map((x) => ServiceLogsModel.fromJson(x)));

String serviceLogsModelToJson(List data) => json.encode(new List.from(data.map((x) => x.toJson())));

class ServiceLogsModel {
String vitCasenumber;
String title;
DateTime createdon;
DateTime modifiedon;
String statuscodeODataCommunityDisplayV1FormattedValue;
int statecode;
String incidentid;
bool vitIsfilemandatory;
String customeridContact;
String vitFilesuploadedtosharepoint;
String vitJsondata;
int vitTypeofform;
bool vitReadstatus;

ServiceLogsModel({
this.vitCasenumber,
this.title,
this.createdon,
this.modifiedon,
this.statuscodeODataCommunityDisplayV1FormattedValue,
this.statecode,
this.incidentid,
this.vitIsfilemandatory,
this.customeridContact,
this.vitFilesuploadedtosharepoint,
this.vitJsondata,
this.vitTypeofform,
this.vitReadstatus,
});

factory ServiceLogsModel.fromJson(Map<String, dynamic> json) => new ServiceLogsModel(
vitCasenumber: json["vit_casenumber"],
title: json["title"],
createdon: DateTime.parse(json["createdon"]),
modifiedon: DateTime.parse(json["modifiedon"]),
statuscodeODataCommunityDisplayV1FormattedValue: json["statuscode@OData.Community.Display.V1.FormattedValue"],
statecode: json["statecode"],
incidentid: json["incidentid"],
vitIsfilemandatory: json["vit_isfilemandatory"],
customeridContact: json["customerid_contact"],
vitFilesuploadedtosharepoint: json["vit_filesuploadedtosharepoint"],
vitJsondata: json["vit_jsondata"],
vitTypeofform: json["vit_typeofform"],
vitReadstatus: json["vit_readstatus"],
);

Map<String, dynamic> toJson() => {
"vit_casenumber": vitCasenumber,
"title": title,
"createdon": createdon.toIso8601String(),
"modifiedon": modifiedon.toIso8601String(),
"statuscode@OData.Community.Display.V1.FormattedValue": statuscodeODataCommunityDisplayV1FormattedValue,
"statecode": statecode,
"incidentid": incidentid,
"vit_isfilemandatory": vitIsfilemandatory,
"customerid_contact": customeridContact,
"vit_filesuploadedtosharepoint": vitFilesuploadedtosharepoint,
"vit_jsondata": vitJsondata,
"vit_typeofform": vitTypeofform,
"vit_readstatus": vitReadstatus,
};
}
`

I am getting the response like this

[
{
"vit_casenumber": "CM1902849",
"title": "Request For Reference Letter",
"createdon": "2019-06-27T04:43:44Z",
"modifiedon": "2019-06-27T04:54:03Z",
"statuscode@OData.Community.Display.V1.FormattedValue": "New",
"statecode": 0,
"incidentid": "e7d38720-9698-e911-a855-000d3ae0a7f8",
"vit_isfilemandatory": false,
"customerid_contact": null,
"vit_filesuploadedtosharepoint": null,
"vit_jsondata": null,
"vit_typeofform": 2,
"vit_readstatus": true
},
{
"vit_casenumber": "CM1902848",
"title": "Request For Reference Letter",
"createdon": "2019-06-26T12:53:13Z",
"modifiedon": "2019-06-26T12:53:17Z",
"statuscode@OData.Community.Display.V1.FormattedValue": "New",
"statecode": 0,
"incidentid": "681bb658-1198-e911-a852-000d3ae0b82e",
"vit_isfilemandatory": false,
"customerid_contact": null,
"vit_filesuploadedtosharepoint": null,
"vit_jsondata": null,
"vit_typeofform": 2,
"vit_readstatus": false
}
]

when I am executing this line

json.decode(response.body);

I am getting this error

Unhandled Exception: type 'List' is not a subtype of type 'String'

Please help me to sort out the problem

Hi Vivek, Can u Please send the solution for this Error

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.