flutter_data_stream_builder 0.0.3

A pragmatic StreamBuilder with sensible defaults

DataStreamBuilder

A pragmatic StreamBuilder with sensible defaults.

😩 The problem with StreamBuilder

StreamBuilder is an essential tool to work with BLoCs or generally any stream.

But with enough streams in our codebase, a lot of boilerplate is introduced. Code gets repetitive and can't be easily reused:

StreamBuilder(
  stream: bloc.stock,
  builder: (context, AsyncSnapshot<Stock> snapshot) {
    if (snapshot.hasData) {
      return Text(snapshot.data.stock.toString());
    } else if (snapshot.hasError) {
      return Text(snapshot.error.toString());
    }
    return Center(child: CircularProgressIndicator());
  },
),

DataStreamBuilder aims to fix these issues for the common usecase:

StreamBuilder(
  stream: bloc.stock,
  builder: (context, Stock stock) => Text(stock.local.toString())
),

This library provides default builders for the loading and error states (can be supplied as loadingBuilder and errorBuilder), and only calls builder when data is present.

Note: if you need fine-grained control over ConnectionStates to the underlying computation, just use StreamBuilder.

👩🏾‍💻 Usage

Using defaults for loading and error states:

DataStreamBuilder<List<Post>>(
  stream: Repository.of<Post>().findAll(),
  builder: (context, List<Post> posts) => ListView(
    children: posts.map((post) => ListTile(title: Text(post.body))).toList(),
  )
)

Custom loading and error widgets:

DataStreamBuilder<List<Post>>(
  stream: Repository.of<Post>().findAll(),
  loadingBuilder: (context) => Center(child: Text('Loading posts...')),
  errorBuilder: (context, error) => PostErrorView(error),
  builder: (context, List<Post> posts) => ListView(
    children: posts.map((post) => ListTile(title: Text(post.body))).toList(),
  )
)

See tests and the Example tab for a full example.

🛠 Extending

We can easily extend the class in order to provide our own app-wide defaults.

For instance, we could implement a branded loader:

class BrandedDataStreamBuilder<T> extends DataStreamBuilder<T> {

  static final brandedLoadingBuilder = (context) => Text('Custom branded loading...');

  BrandedDataStreamBuilder({
    Key key,
    @required Stream<T> stream,
    @required DataWidgetBuilder<T> builder,
    DataErrorWidgetBuilder errorBuilder
  }) :
    assert(builder != null),
    super(
      key: key,
      stream: stream,
      builder: builder,
      loadingBuilder: brandedLoadingBuilder,
      errorBuilder: errorBuilder
    );
}

In action:

➕ Collaborating

Please use Github to open issues and send PRs. Thanks 🙌

📝 License

MIT