Dart issue with getting JSON data - json

Question

I'm trying to get data from JSON, the data is as follows :
For the JSON above, I've generated a Dart Class using this website
the code below works fine with this response : RESPONSE TVSHOW DETAILS, I can see all data loaded successfully in my app, but not with this one RESPONSE TVSHOW DETAILS 2, nothing is loaded
TVShow tvShowFromJson(String str) => TVShow.fromJson(json.decode(str));
String tvShowToJson(TVShow data) => json.encode(data.toJson());
class TVShow {
String backdropPath;
List<CreatedBy> createdBy;
List<int> episodeRunTime;
DateTime firstAirDate;
List<Genre> genres;
String homepage;
int id;
bool inProduction;
List<String> languages;
DateTime lastAirDate;
TEpisodeToAir lastEpisodeToAir;
String name;
TEpisodeToAir nextEpisodeToAir;
List<Network> networks;
int numberOfEpisodes;
int numberOfSeasons;
List<String> originCountry;
String originalLanguage;
String originalName;
String overview;
double popularity;
String posterPath;
List<Network> productionCompanies;
List<Season> seasons;
String status;
String type;
double voteAverage;
int voteCount;
TVShow({
this.backdropPath,
this.createdBy,
this.episodeRunTime,
this.firstAirDate,
this.genres,
this.homepage,
this.id,
this.inProduction,
this.languages,
this.lastAirDate,
this.lastEpisodeToAir,
this.name,
this.nextEpisodeToAir,
this.networks,
this.numberOfEpisodes,
this.numberOfSeasons,
this.originCountry,
this.originalLanguage,
this.originalName,
this.overview,
this.popularity,
this.posterPath,
this.productionCompanies,
this.seasons,
this.status,
this.type,
this.voteAverage,
this.voteCount,
});
factory TVShow.fromJson(Map<String, dynamic> json) => TVShow(
backdropPath: json["backdrop_path"],
createdBy: List<CreatedBy>.from(json["created_by"].map((x) => CreatedBy.fromJson(x))),
episodeRunTime: List<int>.from(json["episode_run_time"].map((x) => x)),
firstAirDate: DateTime.parse(json["first_air_date"]),
genres: List<Genre>.from(json["genres"].map((x) => Genre.fromJson(x))),
homepage: json["homepage"],
id: json["id"],
inProduction: json["in_production"],
languages: List<String>.from(json["languages"].map((x) => x)),
lastAirDate: DateTime.parse(json["last_air_date"]),
lastEpisodeToAir: TEpisodeToAir.fromJson(json["last_episode_to_air"]),
name: json["name"],
nextEpisodeToAir: TEpisodeToAir.fromJson(json["next_episode_to_air"]),
networks: List<Network>.from(json["networks"].map((x) => Network.fromJson(x))),
numberOfEpisodes: json["number_of_episodes"],
numberOfSeasons: json["number_of_seasons"],
originCountry: List<String>.from(json["origin_country"].map((x) => x)),
originalLanguage: json["original_language"],
originalName: json["original_name"],
overview: json["overview"],
popularity: json["popularity"].toDouble(),
posterPath: json["poster_path"],
productionCompanies: List<Network>.from(json["production_companies"].map((x) => Network.fromJson(x))),
seasons: List<Season>.from(json["seasons"].map((x) => Season.fromJson(x))),
status: json["status"],
type: json["type"],
voteAverage: json["vote_average"].toDouble(),
voteCount: json["vote_count"],
);
Map<String, dynamic> toJson() => {
"backdrop_path": backdropPath,
"created_by": List<dynamic>.from(createdBy.map((x) => x.toJson())),
"episode_run_time": List<dynamic>.from(episodeRunTime.map((x) => x)),
"first_air_date":
"${firstAirDate.year.toString().padLeft(4, '0')}-${firstAirDate.month.toString().padLeft(2, '0')}-${firstAirDate.day.toString().padLeft(2, '0')}",
"genres": List<dynamic>.from(genres.map((x) => x.toJson())),
"homepage": homepage,
"id": id,
"in_production": inProduction,
"languages": List<dynamic>.from(languages.map((x) => x)),
"last_air_date":
"${lastAirDate.year.toString().padLeft(4, '0')}-${lastAirDate.month.toString().padLeft(2, '0')}-${lastAirDate.day.toString().padLeft(2, '0')}",
"last_episode_to_air": lastEpisodeToAir.toJson(),
"name": name,
"next_episode_to_air": nextEpisodeToAir.toJson(),
"networks": List<dynamic>.from(networks.map((x) => x.toJson())),
"number_of_episodes": numberOfEpisodes,
"number_of_seasons": numberOfSeasons,
"origin_country": List<dynamic>.from(originCountry.map((x) => x)),
"original_language": originalLanguage,
"original_name": originalName,
"overview": overview,
"popularity": popularity,
"poster_path": posterPath,
"production_companies": List<dynamic>.from(productionCompanies.map((x) => x.toJson())),
"seasons": List<dynamic>.from(seasons.map((x) => x.toJson())),
"status": status,
"type": type,
"vote_average": voteAverage,
"vote_count": voteCount,
};
}
class CreatedBy {
int id;
String creditId;
String name;
int gender;
String profilePath;
CreatedBy({
this.id,
this.creditId,
this.name,
this.gender,
this.profilePath,
});
factory CreatedBy.fromJson(Map<String, dynamic> json) => CreatedBy(
id: json["id"],
creditId: json["credit_id"],
name: json["name"],
gender: json["gender"],
profilePath: json["profile_path"],
);
Map<String, dynamic> toJson() => {
"id": id,
"credit_id": creditId,
"name": name,
"gender": gender,
"profile_path": profilePath,
};
}
class Genre {
int id;
String name;
Genre({
this.id,
this.name,
});
factory Genre.fromJson(Map<String, dynamic> json) => Genre(
id: json["id"],
name: json["name"],
);
Map<String, dynamic> toJson() => {
"id": id,
"name": name,
};
}
class TEpisodeToAir {
DateTime airDate;
int episodeNumber;
int id;
String name;
String overview;
String productionCode;
int seasonNumber;
int showId;
String stillPath;
double voteAverage;
int voteCount;
TEpisodeToAir({
this.airDate,
this.episodeNumber,
this.id,
this.name,
this.overview,
this.productionCode,
this.seasonNumber,
this.showId,
this.stillPath,
this.voteAverage,
this.voteCount,
});
factory TEpisodeToAir.fromJson(Map<String, dynamic> json) => TEpisodeToAir(
airDate: DateTime.parse(json["air_date"]),
episodeNumber: json["episode_number"],
id: json["id"],
name: json["name"],
overview: json["overview"],
productionCode: json["production_code"],
seasonNumber: json["season_number"],
showId: json["show_id"],
stillPath: json["still_path"],
voteAverage: json["vote_average"].toDouble(),
voteCount: json["vote_count"],
);
Map<String, dynamic> toJson() => {
"air_date":
"${airDate.year.toString().padLeft(4, '0')}-${airDate.month.toString().padLeft(2, '0')}-${airDate.day.toString().padLeft(2, '0')}",
"episode_number": episodeNumber,
"id": id,
"name": name,
"overview": overview,
"production_code": productionCode,
"season_number": seasonNumber,
"show_id": showId,
"still_path": stillPath,
"vote_average": voteAverage,
"vote_count": voteCount,
};
}
class Network {
String name;
int id;
String logoPath;
String originCountry;
Network({
this.name,
this.id,
this.logoPath,
this.originCountry,
});
factory Network.fromJson(Map<String, dynamic> json) => Network(
name: json["name"],
id: json["id"],
logoPath: json["logo_path"] == null ? null : json["logo_path"],
originCountry: json["origin_country"],
);
Map<String, dynamic> toJson() => {
"name": name,
"id": id,
"logo_path": logoPath == null ? null : logoPath,
"origin_country": originCountry,
};
}
class Season {
DateTime airDate;
int episodeCount;
int id;
String name;
String overview;
String posterPath;
int seasonNumber;
Season({
this.airDate,
this.episodeCount,
this.id,
this.name,
this.overview,
this.posterPath,
this.seasonNumber,
});
factory Season.fromJson(Map<String, dynamic> json) => Season(
airDate: DateTime.parse(json["air_date"]),
episodeCount: json["episode_count"],
id: json["id"],
name: json["name"],
overview: json["overview"],
posterPath: json["poster_path"],
seasonNumber: json["season_number"],
);
Map<String, dynamic> toJson() => {
"air_date":
"${airDate.year.toString().padLeft(4, '0')}-${airDate.month.toString().padLeft(2, '0')}-${airDate.day.toString().padLeft(2, '0')}",
"episode_count": episodeCount,
"id": id,
"name": name,
"overview": overview,
"poster_path": posterPath,
"season_number": seasonNumber,
};
}
When I tried to catch the error with :
if (snapshot.hasError) {
print('ERROR : ${snapshot.error}');
}
I got this :
I/flutter (16719): ERROR : NoSuchMethodError: The method '[]' was
called on null. I/flutter (16719): Receiver: null I/flutter (16719):
Tried calling: []("air_date")

Answer 1

It could be because the "next_episode_to_air" parameter in the second link (TV show details 2) is actually a null value! You can check for nulls using ?? operator in Dart.
You can have a look at its usage here
In your case, you could use it like this in your TVShow.fromJson method,
nextEpisodeToAir: TEpisodeToAir.fromJson(json["next_episode_to_air"] ?? <your-default-value>),
This will check your code for the value of json["next_episode_to_air"] and put an your default value at it's place if it turns out to be null. You can then deal with this default (or maybe null) value accordingly in your code later.

Answer 2

I have solved the issue with null case handling.In 2nd response, response with key next_episode_to_air is null. Due to this getting error, accessing key on null.
Just handle the possible case for data, currently at factory TVShow.fromJson i.e.
nextEpisodeToAir: json["next_episode_to_air"] == null ? null : TEpisodeToAir.fromJson(json["next_episode_to_air"])