Feed Caching

An abstract base class for managing a feed of type [T] with support for caching and online data fetching. This class is designed to provide a unified interface for handling data operations that involve both local caching and remote API interactions.

Overview

BaseFeedManager provides a robust framework for managing data feeds by:

• Initializing a cache using Hive.
• Loading data from the local cache.
• Saving data to the local cache.
• Fetching new data from a remote API.
• Automatically refreshing the cache based on online connectivity.

This class is generic and can be used with any data type by specifying the type parameter [T]. Subclasses must implement the abstract method fetchDataFromApi to define how to retrieve data from an API.

Flow-breakdown

1. Initialize Feed

   • The BaseFeedManager is initialized with the specific feed type. During initialization:
     • The associated Hive box for caching is set up.
     • Any previously cached feed data is loaded from local storage.

2. Serve Cached Data

   • The feed manager immediately retrieves and serves cached data from local storage to the UI.
   • This ensures that users see previously loaded content while new data is fetched in the background.

3. Fetch Fresh Data

   • The API Service performs a network request to fetch the latest feed data from the server.
   • This operation occurs asynchronously to avoid blocking the UI thread.

4. Update Cache

   • Once fresh data is successfully fetched, it is stored in the cache.
   • The existing cache is cleared and replaced with the new data to ensure that the cache remains up-to-date.

5. UI Update

   • The UI is updated to display the latest feed content.
   • This involves notifying relevant components to refresh and render the updated data, ensuring that users have access to the most recent information.

Constructor

BaseFeedManager(String cacheKey)

Initializes the BaseFeedManager with a unique cache key for Hive.

Parameters:

• cacheKey: A unique string used to identify the cache box in Hive.

Properties

• String cacheKey: The unique key used to access the Hive cache box.
• Box<T> _box: The Hive box that stores the cached data.

Methods

Method

_initialize()

Initializes the Hive box associated with the cacheKey.

Returns:

• Future<void>: Completes when the initialization is finished.

Method

Future<List<T>> loadCachedData()

Loads the data cached in Hive.

Returns:

• Future<List<T>>: A Future that resolves to a list of cached data of type [T].

Method

Future<void> saveDataToCache(List<T> data)

Saves a list of data to the cache, replacing any existing data.

Parameters:

• data: A list of data of type [T] to be saved in the cache.

Returns:

• Future<void>: Completes when the data has been saved to the cache.

Method

Future<List<T>> fetchDataFromApi()

An abstract method that must be implemented by subclasses to fetch data from an API.

Returns:

• Future<List<T>>: A Future that resolves to a list of data of type [T] fetched from the API.

Method

Future<List<T>> getNewFeedAndRefreshCache()

Fetches new data from the API if online, updates the cache, and returns the data. If offline, it loads and returns cached data.

Returns:

• Future<List<T>>: A Future that resolves to a list of the latest data of type [T].

Example Usage

To use BaseFeedManager, create a subclass that implements the fetchDataFromApi method. Here is an example of how to create a concrete implementation:

import 'package:flutter/material.dart';
import 'package:hive/hive.dart';
import 'base_feed_manager.dart'; // Import your BaseFeedManager class

class MyFeedManager extends BaseFeedManager<MyDataType> {
  MyFeedManager() : super('myFeedCacheKey');

  @override
  Future<List<MyDataType>> fetchDataFromApi() async {
    // Replace with your actual API fetching logic
    final response = await http.get(Uri.parse('https://api.example.com/data'));
    if (response.statusCode == 200) {
      final List<dynamic> jsonData = json.decode(response.body);
      return jsonData.map((item) => MyDataType.fromJson(item)).toList();
    } else {
      throw Exception('Failed to load data');
    }
  }
}

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  // Open Hive box
  await Hive.openBox<MyDataType>('myFeedCacheKey');

  final feedManager = MyFeedManager();

  // Fetch and refresh cache
  final data = await feedManager.getNewFeedAndRefreshCache();

  // Use the data
  print(data);
}