load PFIs from known source and cache as shared preference #17
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,22 +1,56 @@ | ||
| import 'dart:convert'; | ||
| import 'package:flutter_starter/features/pfis/pfi.dart'; | ||
| import 'package:hooks_riverpod/hooks_riverpod.dart'; | ||
| import 'package:http/http.dart' as http; | ||
| import 'package:shared_preferences/shared_preferences.dart'; | ||
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| final pfisProvider = FutureProvider<List<Pfi>>((ref) async { | ||
| const url = 'https://raw.githubusercontent.com/TBD54566975/pfi-providers-data/main/pfis.json'; | ||
| const cacheKey = 'pfis_cache'; | ||
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| try { | ||
| // Attempt to fetch data from the URL | ||
| final response = await http.get(Uri.parse(url)); | ||
| if (response.statusCode == 200) { | ||
| // Parse the JSON data directly into a list of Pfi objects | ||
| List<Pfi> pfis = (json.decode(response.body) as List).map((data) { | ||
| return Pfi( | ||
| id: data['id'] as String, | ||
| name: data['name'] as String, | ||
| didUri: data['didUri'] as String, | ||
| ); | ||
| }).toList(); | ||
|
There was a problem hiding this comment. With the serialization change below, you can update to this if you wanna: final pfis = (json.decode(response.body) as List)
.map<Pfi>((p) => Pfi.fromJson(p))
.toList(); |
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| // Save the data to cache | ||
| final prefs = await SharedPreferences.getInstance(); | ||
| await prefs.setString(cacheKey, response.body); | ||
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There was a problem hiding this comment. We can add a provider for this as well so that any code can use Then initialize and override it in Then when you need |
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| return pfis; | ||
| } else { | ||
| // If server returns an unsuccessful response, try loading from cache | ||
| return await _loadFromCache(cacheKey); | ||
| } | ||
| } catch (e) { | ||
| // In case of an error, try loading from cache | ||
| return await _loadFromCache(cacheKey); | ||
| } | ||
|
There was a problem hiding this comment. Another approach I like to use on mobile, to keep things snappy is to always load cache first, then always load from network. That way the users gets the list right away from cache and we can refresh from network after. This would require another provider/notifier which is a bit more complicated. Happy to show how that might work as well if you're interested. There was a problem hiding this comment. good idea - did that. |
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| }); | ||
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| Future<List<Pfi>> _loadFromCache(String cacheKey) async { | ||
| final prefs = await SharedPreferences.getInstance(); | ||
| String? cachedData = prefs.getString(cacheKey); | ||
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| if (cachedData != null) { | ||
| // If cached data is available, parse and return it | ||
| return (json.decode(cachedData) as List).map((data) { | ||
| return Pfi( | ||
| id: data['id'] as String, | ||
| name: data['name'] as String, | ||
| didUri: data['didUri'] as String, | ||
| ); | ||
| }).toList(); | ||
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There was a problem hiding this comment. For this type of stuff, you can add Map<String, dynamic> toJson() {
return {
'id': id,
'name': name,
'didUri': didUri,
};
}
factory Pfi.fromJson(Map<String, dynamic> json) {
return Pfi(
id: json['id'],
name: json['name'],
didUri: json['didUri'],
);
} |
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| } else { | ||
| // If there is no cached data, return an empty list or handle appropriately | ||
| return []; | ||
| } | ||
| } | ||
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super nit: We can make this private to the file to avoid having to pass it to the
_loadFromCachefunction below.