I am trying to get the data from an API and I get the data, but when I show it on the screen I get this error

Assertion failed: file:///home/builder/hotbuilder/packages/flutter/lib/src/widgets/text.dart:378:10 data != null.

I saw some examples, but I still don't understand how to solve it

This is main.dart

    import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
import 'package:flutter_api_git/modelo/repo.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Flutter Demo',
      home: Home(),
    );
  }
}

Future<All> fetchRepos() async {
  final response =
      await http.get(Uri.parse('https://api.github.com/users/IcaroOli/repos'));

  if (response.statusCode == 200) {
    print(response.body);
    return All.fromJson(json.decode(response.body));
  } else {
    throw Exception('Failed to fetch repos!');
  }
}

class Home extends StatefulWidget {
  const Home({Key? key}) : super(key: key);

  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  late Future<All> futureRepo;
  @override
  void initState() {
    super.initState();
    futureRepo = fetchRepos();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('GitHub API!'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: FutureBuilder<All>(
          future: futureRepo,
          builder: (context, snapshot) {
            if (snapshot.hasData) {
              List<Repo> repos = <Repo>[];
              for (int i = 0; i < snapshot.data!.repos.length; i  ) {
                repos.add(
                  Repo(
                    name: snapshot.data.repos[i].name,
                    description: snapshot.data!.repos[i].description,
                    htmlUrl: snapshot.data!.repos[i].htmlUrl,
                    stargazersCount: snapshot.data!.repos[i].stargazersCount,
                  ),
                );
              }
              return ListView(
                children: repos
                    .map(
                      (r) => Card(
                        color: Colors.blue[300],
                        child: Padding(
                          padding: const EdgeInsets.all(8.0),
                          child: Column(
                            mainAxisAlignment: MainAxisAlignment.start,
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: [
                              Row(
                                mainAxisAlignment:
                                    MainAxisAlignment.spaceBetween,
                                children: [
                                  Text(
                                    r.name,
                                    style: const TextStyle(fontSize: 30.0),
                                  ),
                                  Text(r.stargazersCount.toString()),
                                ],
                              ),
                              Text(
                                r.description,
                                style: const TextStyle(fontSize: 23.0),
                              ),
                              Text(r.htmlUrl),
                            ],
                          ),
                        ),
                      ),
                    )
                    .toList(),
              );
            } else if (snapshot.hasError) {
              return const Center(
                child: Text('Error!'),
              );
            } else {
              return const Center(
                child: CircularProgressIndicator(),
              );
            }
          },
        ),
      ),
    );
  }
}

This is repo.dart

class Repo {
  String name;
  String htmlUrl; // hmtl_url
  int stargazersCount; //stargazers_count
  String description;

  Repo(
      {required this.name,
      required this.htmlUrl,
      required this.stargazersCount,
      required this.description});

  factory Repo.fromJson(Map<String, dynamic> json) {
    return Repo(
      name: json['name'],
      htmlUrl: json['html_url'],
      stargazersCount: json['stargazers_count'],
      description: json['description'],
    );
  }
}

class All {
  List<Repo> repos;

  All({required this.repos});

  factory All.fromJson(List<dynamic> json) {
    List<Repo> repos = <Repo>[];
    repos = json.map((r) => Repo.fromJson(r)).toList();
    return All(repos: repos);
  }
}
class Repo {
  String name;
  String htmlUrl; // hmtl_url
  int stargazersCount; //stargazers_count
  String description;

  Repo(
      {required this.name,
      required this.htmlUrl,
      required this.stargazersCount,
      required this.description});

  factory Repo.fromJson(Map<String, dynamic> json) {
    return Repo(
      name: json['name'],
      htmlUrl: json['html_url'],
      stargazersCount: json['stargazers_count'],
      description: json['description'],
    );
  }
}

class All {
  List<Repo> repos;

  All({required this.repos});

  factory All.fromJson(List<dynamic> json) {
    List<Repo> repos = <Repo>[];
    repos = json.map((r) => Repo.fromJson(r)).toList();
    return All(repos: repos);
  }
}

CodePudding user response：

One way to make sure they are never null is to provide fallback values in the factory of Repo, for example an empty string, like this:

factory Repo.fromJson(Map<String, dynamic> json) {
  return Repo(
    name: json['name'] ?? "",
    htmlUrl: json['html_url'] ?? "",
    stargazersCount: json['stargazers_count'] ?? 0,
    description: json['description'] ?? "",
  );
}

CodePudding user response：

This happens when you pass a null value to a text widget.

Try adding empty string if the value is null.

Text(r.name ?? ""),