How to decode a Gzip Http Response in Flutter? - json

Question

I am new to Flutter. I am making a Network Request and I am getting the correct response, but the data is Gzipped. I have decompressed the same in Swift, but with Flutter, I am unable to do that. Can anyone please help?
Here's what I have tried:
import 'dart:convert';
import 'package:http/http.dart';
import 'package:archive/archive.dart';
import 'package:flutter_app/Constants/constants.dart';
class ServiceHelper {
static final sharedInstance = ServiceHelper();
Future<Response> sendRequest({String path, Map<String,dynamic> params}) async {
final String url = Constants.testURL+path;
var body = jsonEncode(params);
Response response = await post(url, body:body);
final gZipped_data = GZipDecoder().decodeBytes(response.bodyBytes);
print(gZipped_data); //flutter: [123, 34, 115, 116, 97, 116, 117, 115, 34, 58, 50, 48, 48, 44, 34, 109, 101, 115, 115, 97, 103, 101, 34, 58, 34, 83, 105, 103, 110, 32, 105, 110, 32, 67, 111, 109, 112, 108, 101, 116, 101, 100, 32, 83, 117, 99, 99, 101, 115, 115, 102, 117, 108, 108, 121, 34, 44, 34, 100, 97, 116, 97, 34, 58, 123, 34, 117, 115, 101, 114, 95, 105, 110, 102, 111, 34, 58, 123, 34, 112, 108, 97, 121, 101, 114, 95, 105, 100, 34, 58, 49, 52, 56, 54, 57, 44, 34, 112, 108, 95, 97, 112, 112, 95, 105, 100, 34, 58, 34, 57, 90, 104, 57, 82, 66, 108, 70, 34, 44, 34, 112, 114, 111, 102, 105, 108, 101, 95, 112, 105, 99, 34, 58, 34, 104, 116, 116, 112, 115, 58, 92, 47, 92, 47, 119, 119, 119, 46, 115, 112, 111, 114, 116, 115, 113, 119, 105, 122, 122, 46, 99, 111, 109, 92, 47, 118, 51, 92, 47, 105, 109, 103, 92, 47, 112, 108, 97, 121, 101, 114, 115, 92, 47, 112, 105, 99, 92, 47, 105, 80, 45, 49, 53, 50, 51, 56, 54, 57, 50, 57, 56, 46, 112, 110, 103, 34, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 116, 101, 99, 104, 121, <…>
//This throws an error: Unhandled Exception: FormatException: Bad UTF-8 encoding 0x8b (at offset 1)
return response;
}
}
//This is the login function and it is in a different file main.dart
Future<void> login(
{String email,
String name,
int source,
String sourceStr,
String picString,
String idToken}) async {
final String playerID = '';
final String token = await getIOSToken().then((token){
return token;
});
Map<String, dynamic> params = {
"email": email,
"name": name,
"player_id": playerID,
"source_id": source,
"profile_pic": picString,
"password": passwordController.text ?? "",
"ios_token":token,
"device_type": "I",
"language_iso": "en",
"referred_by": "loginDefault",
"firebase_id_token": idToken,
"app_version": "4.4.9"
};
Response response = await ServiceHelper.sharedInstance
.sendRequest(path: Constants.login, params: params);
if (response.statusCode == 201) {
// If server returns an OK response, parse the JSON.
return UserDetails.fromJson(json.decode(response.body));
} else {
// If that response was not OK, throw an error.
throw Exception('Failed to load post');
}
}
The expected response is JSON, but as it is Gzipped and I am unable to decompress it, I do not know how to get the JSON from it. I have tried decoding it and it gives me gzipped_data as a List of Integers as you can see above. How can I get the JSON from it?

Answer 1

I'm using GZipCodec from dart:io.
Try it like this to return the response as a String.
Future<String> sendRequest({String path, Map<String,dynamic> params}) async {
final String url = Constants.testURL+path;
var body = jsonEncode(params);
Response response = await post(url, body:body);
final decoded_data = GZipCodec().decode(response.bodyBytes);
return utf8.decode(decoded_data, allowMalformed: true);
}

Answer 2

The body of a response will be automatically uncompressed.
Visit https://api.flutter.dev/flutter/dart-io/HttpClient/autoUncompress.html