Overview

Asynchronous data caching, refetching & invalidation library for Flutter. Fl-Query lets you manage & distribute your async data without touching any global state

Fl-Query makes asynchronous server state management a breeze in flutter

Features

• Async data caching & management
• Smart + effective refetching
• Optimistic updates
• Automatically cached data invalidation & unneeded query/mutation garbage collection
• Infinite pagination via InfiniteQuery
• Lazy persistent cache (Uses hive for persisting query results to disk) (optional)
• Easy to write & understand code. Follows DRY (Don't repeat yourself) convention
• Compatible with both vanilla Flutter & elite flutter_hooks

Installation

Regular installation:

$ flutter pub add fl_query

For elite flutter_hooks user (Welcome to the flutter cool community btw😎)

$ flutter pub add flutter_hooks fl_query_hooks

Basic Usage

Initialize the cache databases in your main method

fl-query uses hive for persisting data to disk

void main()async {
  WidgetsFlutterBinding.ensureInitialized();
  await QueryClient.initialize(cachePrefix: 'fl_query_example');
  runApp(MyApp());
}

In MyApp Widget's build method wrap your MaterialApp with with QueryClientProvider widget

  Widget build(BuildContext context) {
    return QueryClientProvider(
      child: MaterialApp(
        title: 'Fl-Query Example App',
        theme: ThemeData(
          useMaterial3: true,
          primarySwatch: Colors.blue,
        ),
        home: const MyHomePage(),
      ),
    );
  }

Let's write use a Query now FL-Query provides a QueryBuilder widget that creates and listens to the specified Query and re-runs the builder function whenever there's an update

It has 2 required parameters key(unnamed) & builder

class MyApp extends StatelessWidget{
    MyApp({super.key});

    @override
    build(context){
      return QueryBuilder<String, dynamic>(
        'hello',
        () {
          return Future.delayed(
              const Duration(seconds: 6), () => 'Hello World!');
        },
        initial: 'A replacement',
        jsonConfig: JsonConfig(
          fromJson: (json) => json['data'],
          toJson: (data) => {'data': data},
        ),
        onData: (value) {
          debugPrint('onData: $value');
        },
        onError: (error) {
          debugPrint('onError: $error');
        },
        builder: (context, query) {
          if (query.isLoading) {
            return const Center(
              child: CircularProgressIndicator(),
            );
          } else if (query.hasError) {
            return Center(
              child: Text(query.error.toString()),
            );
          }
          return Center(
            child: Text(query.data ?? "Unfortunately, there's no data"),
          );
        },
      );
    }
}

And if you're using flutter_hooks you got that too

class MyApp extends HookWidget{
    MyApp({super.key});

    @override
    build(context){
      final query = useQuery<String, dynamic>(
        'hello',
        () {
          return Future.delayed(
              const Duration(seconds: 6), () => 'Hello World!');
        },
        initial: 'A replacement',
        jsonConfig: JsonConfig(
          fromJson: (json) => json['data'],
          toJson: (data) => {'data': data},
        ),
        onData: (value) {
          debugPrint('onData: $value');
        },
        onError: (error) {
          debugPrint('onError: $error');
        },
      );

      if (query.isLoading) {
        return const Center(
            child: CircularProgressIndicator(),
          );
      } else if (query.hasError) {
        return Center(
          child: Text(query.error.toString()),
        );
      }
      return Center(
        child: Text(query.data ?? "Unfortunately, there's no data"),
      );
    }
}

Why?

The main purpose of Fl-Query is providing the easiest way to manage the messy server-state part requiring the least amount of code with code reusability & performance. This let's you focus more on those cool UI animations & transitions✨. Leave the boring stuff to Fl-Query

Q. Isn't FutureBuilder good?

No, of course not. Unless you're from 2013 or your app is a purely offline app

Q. So FutureProvider from riverpod or provider not enough?

Probably yes. Although riverpod@v2 has added a lot of caching related features but still optimistic updates, periodic refetching & disk persistence are missing. Let's not forget about infinite pagination, it's a nightmare😅. In case of provider, same story. It's a great package but it's not the easiest one for server-state management