nbr 2.1.6

Generic implementation of the network-bound-resource algorithm in Dart

nbr

nbr (Network Bound Resource) is a Dart library for managing resources that are bound to network requests. It simplifies the handling of data fetching from network and local storage, ensuring a consistent and reactive approach to resource management.

Features

• Manages network requests and local storage seamlessly.
• Emits stream updates for different states: loading, success, failed, and empty.
• Provides a structured way to handle data fetching, caching, and mapping.

Installation

Add nbr to your pubspec.yaml file:

dependencies:
  nbr: latest

Then, run pub get to install the package.

Usage

Import the library:

import 'package:nbr/nbr.dart';

Example

class MyNetworkBoundResource extends NetworkBoundResource<MyEntity> {
  Future<void> fetchData() async {
    await fetch<MyDTO>(
      fetchFromAPI: () async {
        // Implement your API call here
        return MyDTO();
      },
      loadFromDB: () async {
        // Implement loading data from the database
        return null;
      },
      storeToDB: (data) async {
        // Implement storing data to the database
      },
      shouldFetch: (data) async {
        // Implement your logic to decide whether to fetch from API
        return true;
      },
      mapDTOToEntity: (dto) {
        // Implement mapping from DTO to entity
        return MyEntity();
      },
    );
  }
}

void main() async {
  final resource = MyNetworkBoundResource();

  resource.stream.listen((resource) {
    if (resource.isLoading) {
      print('Loading...');
    } else if (resource.isSuccess) {
      print('Success: ${resource.data}');
    } else if (resource.isFailed) {
      print('Failed: ${resource.error}');
    } else if (resource.isEmpty) {
      print('No data');
    }
  });

  await resource.fetchData();
}

API

NetworkBoundResource<Entity>

Abstract class representing a resource bound to a network request.

Properties

• Stream<Resource<Entity>> get stream: A stream of Resource objects representing the current state of the resource.

Methods

• Future<void> fetch<DTO>(...): Fetches the resource from the network and emits Resource objects representing the current state.

  • fetchFromAPI: A callback to fetch the resource from the API.
  • loadFromDB: A callback to load the resource from the database.
  • storeToDB: A callback to store the fetched resource to the database.
  • shouldFetch: A callback to determine if the resource should be fetched from the API.
  • mapDTOToEntity: A callback to map the DTO from the API to an entity.

• void dispose(): Disposes of the NetworkBoundResource by closing the StreamController.

Resource<T>

A class representing the state of a resource.

Properties

• bool get isLoading: Indicates if the resource is in a loading state.
• bool get isSuccess: Indicates if the resource has been successfully fetched.
• bool get isFailed: Indicates if the resource fetching has failed.
• bool get isEmpty: Indicates if the resource is empty.
• T? data: The data of the resource.
• Object? error: The error occurred during fetching the resource.

Static Methods

• Resource<T> loading([T? data]): Creates a loading state.
• Resource<T> success(T data): Creates a success state.
• Resource<T> failed(Object error): Creates a failed state.
• Resource<T> empty(): Creates an empty state.