async_builder 1.0.0

Improved Future and Stream builder for Flutter.

async_builder - Improved Future and Stream builder for Flutter.

This package provides AsyncBuilder, a widget similar to StreamBuilder / FutureBuilder which is designed to reduce boilerplate and improve error handling.

How to use

1. Add to dependencies

dependencies:
  async_builder: ^1.0.0

2. Import

import 'package:async_builder/async_builder.dart';

Examples

Future

AsyncBuilder<String>(
  future: myFuture,
  waiting: (context) => Text('Loading...'),
  builder: (context, value) => Text('$value'),
  error: (context, error, stackTrace) => Text('Error! $error'),
)

Stream

AsyncBuilder<String>(
  stream: myStream,
  waiting: (context) => Text('Loading...'),
  builder: (context, value) => Text('$value'),
  error: (context, error, stackTrace) => Text('Error! $error'),
  closed: (context, value) => Text('$value (closed)'),
)

Features

Separate builders

Instead of a single builder, AsyncBuilder allows you to specify separate builders depending on the state of the asynchronous operation:

• waiting(context) - Called when no events have fired yet.
• builder(context, value) - Required. Called when a value is available.
• error(context, error, stackTrace) - Called if there was an error.
• closed(context, value) - Called if the stream was closed.

If any of these are not provided then it defaults to calling builder (potentially with a null value).

Error handling

AsyncBuilder does not silently ignore errors by default.

If an exception occurs and error is provided, the widget will rebuild and call that builder. Otherwise, if error is not provided and silent not true then the exception and stack trace will be printed to console (default behavior).

Initial value

If initial is provided, it is used in place of the value before one is available.

RxDart ValueStream

If stream is a ValueStream (BehaviorSubject) holding an existing value, that value will be available immediately on first build.

Stream pausing

The StreamSubscription for this widget can be paused with the pause parameter, this is useful if you want to notify the upstream StreamController that you don't need updates.