Creare un client GraphQL in Dart

In questo articolo vediamo come creare un semplice client GraphQL in Dart.

Come "server" useremo QraphQLPlaceholder.

Prima di tutto installiamo le libreria:

dart pub add graphql

Qui sotto un pò di codice; ho messo tutto insieme per comodità:

import 'package:graphql/client.dart';

class User {
  final int id;
  final String name;
  final String email;

  User({required this.id, required this.name, required this.email});

  factory User.fromJson(Map<String, dynamic> json) {
    return User(
      id: int.parse(json['id'].toString()),
      name: json['name'] as String,
      email: json['email'] as String,
    );
  }
}

void main() async {
  final HttpLink httpLink = HttpLink(
    'https://graphqlplaceholder.vercel.app/graphql',
  );

  final GraphQLClient client = GraphQLClient(
    link: httpLink,
    cache: GraphQLCache(),
  );

  const String queryListaUtenti = r'''
    query ListaUtenti {
      users {
        id
        name
        email
      }
    }
  ''';

  final QueryOptions options = QueryOptions(document: gql(queryListaUtenti));

  print('Invio della query GraphQL in Dart...');

  try {
    final QueryResult result = await client.query(options);

    if (result.hasException) {
      print('Errore: ${result.exception.toString()}');
      return;
    }

    final List<dynamic> usersJson = result.data?['users'] ?? [];

    final List<User> users = usersJson
        .map((json) => User.fromJson(json as Map<String, dynamic>))
        .toList();

    print('n--- Dati Lista Utenti (${users.length} risultati) ---');

    for (var user in users) {
      print('ID: ${user.id}, Nome: ${user.name}, Email: ${user.email}');
    }

    print('--------------------------------------------------n');
  } catch (e) {
    print('Errore imprevisto: $e');
  }
}

Enjoy!