Have a client that automatically uses the best practice client on each platform

[Hixie]

The example at https://github.com/dart-lang/http/tree/master/pkgs/flutter_http_example is great, but it seems like it could be wrapped into its own Client, which could then be exposed as a package:http_optimal or something that itself does all the importing and so forth. That way, as new clients are added for new platforms, apps automatically adapt, and we don't have to have the code from the sample duplicated into many apps.

[brianquinlan]

Hey @Hixie ! Yeah, the setup sucks, especially the conditional imports that are required for browser support.

I've resisted offering a combined Client because configuration (persistence, caching, etc.) is very client-specific. package:native_dio_adapter does provide a single client that wraps package:cupertino_http and package:cronet_http.

[Hixie]

FWIW in my use case I ended up just creating my own tiny package that takes the superset of arguments I wanted to provide to the various clients, and provides them to those who want them. So some arguments have no effect on some platforms, but that's basically what happens anyway in the code one would use if basing it on the sample.

[brianquinlan]

If the package is public, could you provide a link?

[Hixie]

not yet public but it's basically four files, http.dart, http_io.dart, http_stub.dart, and http_web.dart:

// http.dart
export 'package:http/http.dart';
export 'http_stub.dart'
    if (dart.library.io) 'http_io.dart'
    if (dart.library.js_interop) 'http_web.dart';

// http_stub.dart
import 'package:http/http.dart';

Client createClient({
  String? userAgent,
  int? cacheSize,
}) {
  throw UnimplementedError();
}

// http_io.dart
import 'dart:io';

import 'package:cronet_http/cronet_http.dart';                                                       
import 'package:cupertino_http/cupertino_http.dart';
import 'package:http/http.dart';
import 'package:http/io_client.dart';

Client createClient({
  String? userAgent,
  int? cacheSize,
}) {
  if (Platform.isAndroid) {                                                                          
    final CronetEngine engine = CronetEngine.build(                                                  
      cacheMode: cacheSize == null ? CacheMode.disabled : CacheMode.memory,                          
      cacheMaxSize: cacheSize,                                                                       
      userAgent: userAgent,                                                                          
    );                                                                                               
    return CronetClient.fromCronetEngine(engine);                                                    
  }                                                                                                  
  if (Platform.isIOS || Platform.isMacOS) {
    final URLSessionConfiguration config = URLSessionConfiguration.defaultSessionConfiguration();
    if (cacheSize != null)
      config.cache = URLCache.withCapacity(memoryCapacity: cacheSize, diskCapacity: cacheSize);
    if (userAgent != null)
      config.httpAdditionalHeaders = <String, String>{'User-Agent': userAgent};
    return CupertinoClient.fromSessionConfiguration(config);
  }
  return IOClient(HttpClient()..userAgent = userAgent);
}

// http_web.dart
import 'package:fetch_client/fetch_client.dart';
import 'package:http/http.dart';

Client createClient({
  String? userAgent,
  int? cacheSize,
}) {
  return FetchClient(mode: RequestMode.sameOrigin);
}

(caveat: i'm using a version of Flutter that currently crashes with cronet, so that code is actually commented out locally currently, but updating flutter to fix that is on my short-term list.)

This is basically just the sample code but wrapped in a library.