Flutter : Future Builder receive null from calsses - api

Question

I am trying to make live score app ,I have a model created by quiqtype.io from json :
import 'dart:convert';
Live liveFromJson(String str) => Live.fromJson(json.decode(str));
String liveToJson(Live data) => json.encode(data.toJson());
class Live {
Live({
this.success,
this.data,
});
bool success;
Data data;
factory Live.fromJson(Map<String, dynamic> json) => Live(
success: json["success"],
data: Data.fromJson(json["data"]),
);
Map<String, dynamic> toJson() => {
"success": success,
"data": data.toJson(),
};
}
class Data {
Data({
this.fixtures,
this.nextPage,
this.prevPage,
});
List<Fixture> fixtures;
String nextPage;
bool prevPage;
factory Data.fromJson(Map<String, dynamic> json) => Data(
fixtures: List<Fixture>.from(
json["fixtures"].map((x) => Fixture.fromJson(x))),
nextPage: json["next_page"],
prevPage: json["prev_page"],
);
Map<String, dynamic> toJson() => {
"fixtures": List<dynamic>.from(fixtures.map((x) => x.toJson())),
"next_page": nextPage,
"prev_page": prevPage,
};
}
class Fixture {
Fixture({
this.id,
this.date,
this.time,
this.round,
this.homeName,
this.awayName,
this.location,
this.leagueId,
this.competitionId,
this.homeId,
this.awayId,
this.competition,
this.league,
});
String id;
DateTime date;
String time;
String round;
String homeName;
String awayName;
String location;
String leagueId;
String competitionId;
String homeId;
String awayId;
Competition competition;
League league;
factory Fixture.fromJson(Map<String, dynamic> json) => Fixture(
id: json["id"],
date: DateTime.parse(json["date"]),
time: json["time"],
round: json["round"],
homeName: json["home_name"],
awayName: json["away_name"],
location: json["location"],
leagueId: json["league_id"],
competitionId: json["competition_id"],
homeId: json["home_id"],
awayId: json["away_id"],
competition: Competition.fromJson(json["competition"]),
league: json["league"] == null ? null : League.fromJson(json["league"]),
);
Map<String, dynamic> toJson() => {
"id": id,
"date":
"${date.year.toString().padLeft(4, '0')}-${date.month.toString().padLeft(2, '0')}-${date.day.toString().padLeft(2, '0')}",
"time": time,
"round": round,
"home_name": homeName,
"away_name": awayName,
"location": location,
"league_id": leagueId,
"competition_id": competitionId,
"home_id": homeId,
"away_id": awayId,
"competition": competition.toJson(),
"league": league == null ? null : league.toJson(),
};
}
class Competition {
Competition({
this.id,
this.name,
});
String id;
String name;
factory Competition.fromJson(Map<String, dynamic> json) => Competition(
id: json["id"],
name: json["name"],
);
Map<String, dynamic> toJson() => {
"id": id,
"name": name,
};
}
class League {
League({
this.id,
this.name,
this.countryId,
});
String id;
String name;
String countryId;
factory League.fromJson(Map<String, dynamic> json) => League(
id: json["id"],
name: json["name"],
countryId: json["country_id"],
);
Map<String, dynamic> toJson() => {
"id": id,
"name": name,
"country_id": countryId,
};
}
the i create API service class :
import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:myexpect/models/match_fixture.dart';
class Api {
Future<Live> get_fixture() async {
var fixture_model = null;
var client = http.Client();
try {
var url =
'https://livescore-api.com/api-client/fixtures/matches.json?key=xxxxxxC&secret=yyyyy&page=1';
var response = await client.get(url);
if (response.statusCode == 200) {
var jsonString = response.body;
var jsonMap = json.decode(jsonString);
fixture_model = Live.fromJson(jsonMap);
print(jsonMap ): //--- printed the list in console successfully
}
} catch (Exception) {
return fixture_model;
}
}
}
I am now trying to view this data's in future building in this page :
import 'package:flutter/material.dart';
import '../services/live_score_api.dart';
import '../models/match_fixture.dart';
class LiveScore extends StatefulWidget {
#override
_LiveScoreState createState() => _LiveScoreState();
}
class _LiveScoreState extends State<LiveScore> {
Future<Live> _fixtures;
#override
void initState() {
_fixtures = Api().get_fixture();
super.initState();
}
#override
Widget build(BuildContext context) {
return FutureBuilder<Live>(
future: _fixtures,
builder: (ctx, snapshot) {
if (snapshot.connectionState == ConnectionState.none ||
snapshot.connectionState == ConnectionState.waiting ||
snapshot.connectionState == ConnectionState.active ||
snapshot.data == null) {
return Container(
child: Text('Loading.......'),
);
} else {
return ListView.builder(
itemCount: snapshot.data.data.fixtures.length,
itemBuilder: (ctx, index) {
var data = snapshot.data.data.fixtures[index];
return Text(data.time);
});
}
},
);
}
}
when i load this page ,the list of data printed successfully at console but the future builder receive null ,therefore just the text 'Loading ...' is viewed ,and no error no exception found

Answer 1

You want to implement your future builder like this:
return FutureBuilder<Live>(
future: _fixtures,
builder: (context, snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.none:
case ConnectionState.waiting:
case ConnectionState.active:
// Loading widget
return CircularProgressIndicator();
case ConnectionState.done:
if (snapshot.hasError) {
// return error widget
}
if (snapshot.hasData) {
return ListView.builder(
itemCount: snapshot.data.data.fixtures.length,
itemBuilder: (ctx, index) {
var data = snapshot.data.data.fixtures[index];
return Text(data.time);
});
}
}
},
);
On top of that, you catch the exception, but you don't throw an exception. So it will not throw an error. Which is kinda what you want to know in a future builder. I recommend throwing an exception.

Answer 2

I found my error ,is here :
import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:myexpect/models/match_fixture.dart';
class Api {
Future<Live> get_fixture() async {
var fixture_model = null;
var client = http.Client();
try {
var url =
'https://livescore-api.com/api-client/fixtures/matches.json?key=xxxxxxC&secret=yyyyy&page=1';
var response = await client.get(url);
if (response.statusCode == 200) {
var jsonString = response.body;
var jsonMap = json.decode(jsonString);
fixture_model = Live.fromJson(jsonMap);
print(jsonMap ): //--- printed the list in console successfully
}
} catch (Exception) {
return fixture_model;
}
}
}
I forgot to return the list outside catch exception ,after i added return it is fixed :
import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:myexpect/models/match_fixture.dart';
class Api {
Future<Live> get_fixture() async {
var fixture_model = null;
var client = http.Client();
try {
var url =
'https://livescore-api.com/api-client/fixtures/matches.json?key=xxxxxxC&secret=yyyyy&page=1';
var response = await client.get(url);
if (response.statusCode == 200) {
var jsonString = response.body;
var jsonMap = json.decode(jsonString);
fixture_model = Live.fromJson(jsonMap);
print(jsonMap ): //--- printed the list in console successfully
}
} catch (Exception) {
return fixture_model;
}
return fixture_model; //------------I added this line that i forgot :)
}
}