Tutorial: Integrating GraphQL with Flutter

Yo wassup Flutter devs!

Today, we're diving deep into the world of GraphQL and Flutter. By the end of this tutorial, you'll have a solid understanding of how to integrate GraphQL with your Flutter apps.

So, grab your favorite beverage, and let's get started!

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1. Why GraphQL?

Before we jump into the integration, let's quickly touch upon why you might want to use GraphQL:

• Flexibility: Request only the data you need.
• Strongly Typed: No more guessing about data types.
• Single Endpoint: Say goodbye to multiple REST endpoints.

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2. Setting Up Your Flutter Project

First things first, create a new Flutter project:

flutter create graphql_flutter_app
cd graphql_flutter_app

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3. Dependencies

Add the necessary dependencies to your pubspec.yaml:

dependencies:
  flutter:
    sdk: flutter
  graphql_flutter: ^latest_version_here

Run flutter pub get to install them.

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4. Setting Up GraphQL Client

Create a new file graphql_client.dart:

import 'package:flutter/material.dart';
import 'package:graphql_flutter/graphql_flutter.dart';

ValueNotifier<GraphQLClient>? clientFor({required String uri}) {
  final HttpLink httpLink = HttpLink(uri);

  final ValueNotifier<GraphQLClient> client = ValueNotifier<GraphQLClient>(
    GraphQLClient(
      link: httpLink,
      cache: GraphQLCache(store: InMemoryStore()),
    ),
  );

  return client;
}

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5. Wrap Your App

In your main.dart, wrap your app with GraphQLProvider and CacheProvider:

import 'package:graphql_flutter/graphql_flutter.dart';
import 'graphql_client.dart';

void main() {
  final client = clientFor(uri: 'https://your-graphql-endpoint.com');
  runApp(MyApp(client: client!));
}

class MyApp extends StatelessWidget {
  final ValueNotifier<GraphQLClient> client;

  MyApp({required this.client});

  @override
  Widget build(BuildContext context) {
    return GraphQLProvider(
      client: client,
      child: CacheProvider(
        child: MaterialApp(
          title: 'GraphQL Flutter',
          home: HomePage(),
        ),
      ),
    );
  }
}

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6. Crafting Queries

For this tutorial, let's assume we're fetching a list of books. Create a new file queries.dart:

const String getBooks = r'''
  query GetBooks {
    books {
      title
      author
    }
  }
''';

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7. Fetching Data

In your HomePage widget:

import 'package:graphql_flutter/graphql_flutter.dart';
import 'queries.dart';

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('GraphQL Flutter')),
      body: Query(
        options: QueryOptions(document: gql(getBooks)),
        builder: (QueryResult? result, {VoidCallback? refetch, FetchMore? fetchMore}) {
          if (result!.hasException) {
            return Text(result.exception.toString());
          }

          if (result.isLoading) {
            return CircularProgressIndicator();
          }

          final books = result.data?['books'];
          return ListView.builder(
            itemCount: books?.length ?? 0,
            itemBuilder: (context, index) {
              final book = books![index];
              return ListTile(
                title: Text(book['title']),
                subtitle: Text(book['author']),
              );
            },
          );
        },
      ),
    );
  }
}

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8. Mutations

If you want to modify data, GraphQL has mutations. Here's a quick example:

const String addBook = r'''
  mutation AddBook($title: String!, $author: String!) {
    addBook(title: $title, author: $author) {
      title
      author
    }
  }
''';

// In your widget:
Mutation(
  options: MutationOptions(document: gql(addBook)),
  builder: (RunMutation runMutation, QueryResult? result) {
    return ElevatedButton(
      onPressed: () {
        runMutation({'title': 'New Book', 'author': 'John Doe'});
      },
      child: Text('Add Book'),
    );
  },
);

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9. Conclusion

And there you have it! A concise, end-to-end guide on integrating GraphQL with Flutter. With GraphQL's flexibility and Flutter's ease of use, you're now equipped to build powerful apps with a streamlined data-fetching process.

Remember, practice makes perfect. So, play around, experiment, and happy coding! 🚀

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