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Making a network call in Flutter is easy |
when you use the popular http package. |
This abstracts away a lot of the networking |
that you might normally implement yourself, |
making it simple to make network calls.To use the http package, add it to your dependencies in pubspec.yaml:To make a network request, |
call await on the async function http.get(): |
<code_start>Future<void> loadData() async { |
final Uri dataURL = Uri.parse( |
'https://jsonplaceholder.typicode.com/posts', |
); |
final http.Response response = await http.get(dataURL); |
setState(() { |
data = jsonDecode(response.body); |
}); |
}<code_end> |
<topic_end> |
<topic_start> |
How do I show the progress for a long-running task? |
In Xamarin.Forms you would typically create a loading indicator, |
either directly in XAML or through a 3rd party plugin such as AcrDialogs.In Flutter, use a ProgressIndicator widget. |
Show the progress programmatically by controlling |
when it’s rendered through a boolean flag. |
Tell Flutter to update its state before your long-running task starts, |
and hide it after it ends.In the example below, the build function is separated into three different |
functions. If showLoadingDialog is true |
(when widgets.length == 0), then render the ProgressIndicator. |
Otherwise, render the ListView with the data returned from a network call. |
<code_start>import 'dart:async'; |
import 'dart:convert'; |
import 'package:flutter/material.dart'; |
import 'package:http/http.dart' as http; |
void main() { |
runApp(const SampleApp()); |
} |
class SampleApp extends StatelessWidget { |
const SampleApp({super.key}); |
@override |
Widget build(BuildContext context) { |
return const MaterialApp( |
title: 'Sample App', |
home: SampleAppPage(), |
); |
} |
} |
class SampleAppPage extends StatefulWidget { |
const SampleAppPage({super.key}); |
@override |
State<SampleAppPage> createState() => _SampleAppPageState(); |
} |
class _SampleAppPageState extends State<SampleAppPage> { |
List<Map<String, dynamic>> data = <Map<String, dynamic>>[]; |
@override |
void initState() { |
super.initState(); |
loadData(); |
} |
bool get showLoadingDialog => data.isEmpty; |
Future<void> loadData() async { |
final Uri dataURL = Uri.parse( |
'https://jsonplaceholder.typicode.com/posts', |
); |
final http.Response response = await http.get(dataURL); |
setState(() { |
data = jsonDecode(response.body); |
}); |
} |
Widget getBody() { |
if (showLoadingDialog) { |
return getProgressDialog(); |
} |
return getListView(); |
} |
Widget getProgressDialog() { |
return const Center(child: CircularProgressIndicator()); |
} |
ListView getListView() { |
return ListView.builder( |
itemCount: data.length, |
itemBuilder: (context, index) { |
return getRow(index); |
}, |
); |
} |
Widget getRow(int index) { |
return Padding( |
padding: const EdgeInsets.all(10), |
child: Text('Row ${data[index]['title']}'), |
); |
} |
@override |
Widget build(BuildContext context) { |
return Scaffold( |
appBar: AppBar(title: const Text('Sample App')), |
body: getBody(), |
); |
} |
}<code_end> |
<topic_end> |
<topic_start> |
Project structure & resources |
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