_CastError (type '_InternalLinkedHashMap<dynamic, dynamic>' is not a subtype of type 'Map<String, dynamic>' in type cast)

Question

Im using Dart "json_serializable" package to deserialize below Firestore data structure in Flutter application.

{
googleBookId: jjl4BgAAQBAJ, 
providers: [
    {providerId: 2FA9fULKLLf7VUPPFnFRnv}, 
    {providerId: 8UYTGUHY7UJS432FVBJRnv}
]
}

And below is the Model class to map:

@JsonSerializable()
class Book {

  String googleBookId;
  List<Provider> providers;

  Book(this.googleBookId,
  {List<Provider> providers})
  : providers = providers ?? <Provider>[];

  factory Book.fromJson(Map<String, dynamic> map) => _$BookFromJson(map);

  Map<String, dynamic> toJson() => _$BookToJson(this);
}

@JsonSerializable()
class Provider {

  String providerId;

  Provider(this.providerId);

  factory Provider.fromJson(Map<String, dynamic> map) => _$ProviderFromJson(map);

  Map<String, dynamic> toJson() => _$ProviderToJson(this);
}

While deserializing I'm getting following error

_CastError (type '_InternalLinkedHashMap' is not a subtype of type 'Map' in type cast)

Is there any other library that I can use to deserialize document?

Solution 1

As posted in other question I was able to deserializing Firestore document by encode in to JSON string and back to JSON object before deserialization.

@Chiziaruhoma Ogbonda thanks for clarification, it helps me to think in other way rather directly tying to deserialize document.

Solution 2

Okay so i don't know if you know but then firestore sends you a Map not JSON. You're trying to use JSON Serializer. JSON is Map<String,dynamic> while firestore sends Map<dynamic,dynamic>. So you can't use parse it as json.

Check this out https://medium.com/@atul.sharma_94062/how-to-use-cloud-firestore-with-flutter-e6f9e8821b27

Solution 3

The solution is to use the anyMap and explicitToJson properties.

@JsonSerializable(explicitToJson: true, anyMap: true)
class Book {

}