Why is Flutter Dart application throwing an XMLHttpRequest error when test programme and POSTMAN do not? - flutter

Question

I have an application that was working doing http.get requests on an Ubuntu virtual machine hosting a postgres DB and an API using Hapi/node. The VM disk become corrpupted and following the rebuild, the http.get now throws an XMLHttpRequest error. However, a test programme doing the same request works fine and a test GET using POSTMAN works fine as well. I'm stumped as to why this is the case.
The code that is throwing the error is as follows (the getScores() function):
import 'package:noxo/functions.dart' as func;
import 'dart:convert';
import 'package:http/http.dart' as http;
class DataManager {
Map<dynamic, dynamic> results = {}; // Return values from DB parameter query
double difficulty = 5; // Level of difficulty (1- easiest to 5-hardest)
// Address of API for data requests
final _apiAddress = 'http://192.168.1.201:4044/';
bool _httpAvailable = true; // Assume that http is available
int getHumanScore() {
func.debugPrint('httpAvailable is $_httpAvailable');
if (_httpAvailable && results.isNotEmpty) {
func.debugPrint('Returning HUMAN score');
return results['humanwin'];
} else {
return 0;
}
}
int getDrawScore() {
if (_httpAvailable && results.isNotEmpty) {
return results['draws'];
} else {
return 0;
}
}
int getComputerScore() {
if (_httpAvailable && results.isNotEmpty) {
return results['computerwin'];
} else {
return 0;
}
}
void setDifficulty(double value) {
func.debugPrint('Set difficulty = $value');
difficulty = value;
}
double getDifficulty() {
func.debugPrint('Get difficulty is $difficulty');
return difficulty;
}
void getScores(Function() updateScores) async {
if (_httpAvailable) {
// If we haven't had a previous http error - read the scores
try {
dynamic _parsedAddress = Uri.parse(_apiAddress);
final response = await http.get(_parsedAddress);
func.debugPrint(
'doing getScores. Address = $_apiAddress. statusCode = ${response.statusCode}');
Map decodedResponse = jsonDecode(response.body) as Map;
if (response.statusCode == 200) {
func.debugPrint('getScores response: $decodedResponse');
results = decodedResponse;
updateScores(); // Update scores on main.dart
} else {
throw Exception('Unable to fetch products from the REST API');
}
} catch (e) {
func.debugPrint('getScores. Error is $e.');
_httpAvailable = false; // Disable http checks because we had an error
results =
{}; // Return an empty map if the internet connection is not available
}
}
}
// Put data about scores into the database
Future<void> putScores(String resultPath) async {
// Only try to put the scores if http is available
if (_httpAvailable) {
try {
String address = '$_apiAddress$resultPath';
func.debugPrint('http address: $address');
var response = await http.post(Uri.parse(address));
func.debugPrint('http response: ${response.body.toString()}');
// Check for sucess, throw an error if it didn't work
if (response.statusCode == 200 ||
response.statusCode == 201 ||
response.statusCode == 204) {
return;
} else {
throw Exception(
'Unable to update results from the REST API. Status Code: ' +
response.statusCode.toString());
}
} catch (e) {
_httpAvailable = false; // Disable http requests
}
}
}
}
The output when "getScores()" is called is:
getScores. Error is XMLHttpRequest error..
The Hapi interface code is as follows:
'use strict';
const Hapi = require('#hapi/hapi');
const { options } = require('#hapi/hapi/lib/cors');
const Inert = require('#hapi/inert');
const HapiPostgresConnection = require('hapi-postgres-connection');
const path = require('path');
const debug = true;
const init = async () => {
const server = Hapi.server({
port: 4044,
host: '192.168.1.201',
//host: '0.0.0.0',
routes: {
cors: false
/*
{
origin: ['192.168.*'], // an array of origins or 'ignore'
headers: ['Authorization'], // an array of strings - 'Access-Control-Allow-Headers'
exposedHeaders: ['Accept'], // an array of exposed headers - 'Access-Control-Expose-Headers',
additionalExposedHeaders: ['Accept'], // an array of additional exposed headers
maxAge: 60,
credentials: false // boolean - 'Access-Control-Allow-Credentials'
*/
}
});
await server.register([{
plugin: HapiPostgresConnection
},
{
plugin: Inert
}]);
server.route({
method: 'GET',
path: '/',
handler: async function (request, h) {
let id = '1';
let statement = `SELECT * FROM scores WHERE id = ${id}`;
debugPrint(`Doing GET. Statement = ${statement}`);
try {
const result = await request.pg.client.query(statement);
debugPrint(`After GET. Result = ${result}. Response = ${h.response()}`);
return h.response(result.rows[0]);
} catch (err) {
console.log(err);
}
}
});
server.route({
method: 'GET',
path: '/noxo',
handler: (request, h) => {
return h.file('/home/mike/programming/noxo/index.html');
}
});
server.route({
method: 'GET',
path: '/fwebtest',
handler: (request, h) => {
return h.file('index.html', options [{confine: false}]);
},
options: {
files: {
relativeTo: path.join(__dirname, 'fwebtest')
},
},
});
server.route({
method: 'GET',
path: '/webtest',
handler: (request, h) => {
return h.file('./webtest/index.html', options [{confine: false}])
}
});
server.route({
method: ['PUT', 'POST'],
path: '/',
handler: async function (request, h) {
let statement = 'update scores set';
var jsonData = request.payload;
if (jsonData.hasOwnProperty('id')) {
delete jsonData.id;
}
var first = true
for (var key of Object.keys(jsonData)) {
if (!first) {
statement = statement + ",";
}
statement = statement + ' ' + key + ' = ' + jsonData[key];
first = false;
}
statement = statement + ' where id = 1'
debugPrint(`Doing PUT. Statement = ${statement}`);
try {
const result = await request.pg.client.query(statement);
return h.response(result.rows[0]);
} catch (err) {
console.log(err);
}
}
});
await server.start();
console.log('Server running on %s', server.info.uri);
};
function buildStatement(element, index, array) {
if (index != 'id') {
statement = statement + index + ' = ' + value + ' ';
}
return this;
}
function debugPrint(value){
if (debug == true){
console.log(value);
}
}
process.on('unhandledRejection', (err) => {
console.log(err);
process.exit(1);
});
init();
The test dart programme, which works, is as follows:
import 'dart:convert';
import 'package:http/http.dart' as http;
// Address of API for data requests
final _apiAddress = 'http://192.168.1.201:4044/';
// Global variables
bool _httpAvailable = true; // Has http conect worked? Assume yes.
const bool debug = true; // Global bebug print variable.
void main() async {
// Get the scores from the API
Map scores = await _getScores();
}
// Function to get the scores using http command
Future<Map> _getScores() async {
debugPrint('Doing GET...');
dynamic response;
Map decodedResponse = {};
try {
dynamic _parsedAddress = Uri.parse(_apiAddress);
response = await http.get(_parsedAddress);
decodedResponse = jsonDecode(response.body) as Map;
} catch (e) {
debugPrint('getScores. Error is $e.');
_httpAvailable = false; // Disable http checks because we had an error
decodedResponse =
{}; // Return an empty map if the internet connection is not available
}
if (response.statusCode == 200) {
debugPrint('response.body:');
debugPrint(response.body);
debugPrint('GET successful... code: ' + response.statusCode.toString());
debugPrint(' ');
return decodedResponse;
} else {
throw Exception('Unable to fetch products from the REST API. Error code: ' +
response.statusCode.toString());
}
}
debugPrint(String message) {
if (debug == true) {
print(message);
}
}
The output from this programme is:
D:\Sync\Programming\Flutter\http_get>dart run
Building package executable...
Built http_test:http_test.
Doing GET...
response.body:
{"id":1,"humanwin":3,"draws":0,"computerwin":0}
GET successful... code: 200
The POSTMAN results are:
I assume that this is a CORS issue from what I have read about XMLHttpRequest errors, but believe I have disabled CORS in the Hapi interface. The application class, test programme and POSTMAN test all pre-date the Ubuntu VM rebuild so the only thing that has changed is the VM. The Hapi code was backed up so that shouldn't have changed either, although I can't quite remember when I took the last backup.
Does anyone have any ideas about why the test programme and POSTMAN work, but my DataManager class in my application doesn't?

Answer 1

In the routes definition for Hapi, cors needs to be set to true as below.
const server = Hapi.server({
port: xxxx,
host: 'xxx.xxx.xxx.xxx',
routes: {
cors: true
}
});