I recommend seeing first – installation of Homebrew and asdf on Ubuntu (it’s short, only 5 commands)
📘 Official Documentation
⭐ Popular Frameworks (learning curve low → high):
- Shelf — Simple for APIs.
- Dart Frog — A fast, minimalistic backend framework for Dart
- Angel — Express-style, more complete.
- Serverpod — Larger, microservices-oriented.
Note: Let’s not forget that the most important thing Dart has today is Flutter, although it almost needs its own section.
🛠️ Installing Dart on Ubuntu
Via APT (official repository)
sudo apt update
sudo apt install apt-transport-https
sudo sh -c 'wget -qO- https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add -'
sudo sh -c 'wget -qO /etc/apt/sources.list.d/dart_stable.list https://storage.googleapis.com/dart-archive/channels/stable/release/latest/linux_packages/dart_stable.list'
sudo apt update
sudo apt install dart
🍺 Installation with Homebrew
brew install dart
📦 Package Manager: pub (built into Dart)
dart pub add <package>
dart pub get
🟩 ASDF for Dart
System dependencies
sudo apt update
sudo apt install curl git unzip
Install plugin + version
asdf plugin add dart https://github.com/patoconnor43/asdf-dart.git
asdf list-all dart
asdf install dart 3.4.0
asdf global dart 3.4.0
Example .tool-versions
dart 3.4.0
📝▶️ Create and run a Dart file
Create file
mkdir app && cd app
touch hola.dart
Code hola.dart
void main() {
print('Hola Mundo desde Dart!');
}
Run
dart run hola.dart
🟦 Basic examples in Dart
NOTE: both codes are compatible with Dart 3.9
EX: 1 Static file web server.
What it does:
- Defines the name of the query parameter
- Gets the value of the query parameter from the URL
- htmlEscape sanitizes the received text by removing special characters like < and > into HTML entities.
- Renders the value received from the query parameter inside the
<H1>tag
📝 Create file: touch server.dart
▶️ Content of server.dart
import 'dart:convert';
import 'dart:io';
void main() async {
final server = await HttpServer.bind(InternetAddress.loopbackIPv4, 9000);
print('Servidor corriendo en http://localhost:9000');
await for (HttpRequest request in server) {
final params = request.uri.queryParameters;
final username = params['username'] ?? 'invitado';
final escaped = htmlEscape.convert(username);
final htmlContent = """
<!DOCTYPE html>
<html lang="es">
<head>
<meta charset="UTF-8">
<title>Hola</title>
</head>
<body style="text-align:center">
<img src="https://dev.to/oscarpincho/mejora-ubuntu-con-homebrew-y-asdf-gestor-de-versiones-multiples-4nka" />
<h1>Hola, $escaped</h1>
</body>
</html>
""";
request.response.headers.contentType = ContentType.html;
request.response.write(htmlContent);
await request.response.close();
}
}
run the project / start the server
dart run server.dart
👉 visit:
http://localhost:9000/?username=Homero
To test URL sanitization:
http://localhost:9000/?username=<h1>--Homer--</h1>
EX: 2 JSON REST API
What it does:
- Reads the data from a
data.jsonfile - Exposes 1 endpoint with that data
- A list of characters at
/characters - And the data of a character by id
/characters/:id
Example file: data.json
[
{
"id": 1,
"age": 39,
"name": "Homer Tompson",
"portrait_path": "https://cdn.thesimpsonsapi.com/500/character/1.webp"
},
{
"id": 2,
"age": 39,
"name": "Marge Simpson",
"portrait_path": "https://cdn.thesimpsonsapi.com/500/character/2.webp"
},
]
📝 Create file: touch api.dart
▶️ Content of api.dart
import 'dart:convert';
import 'dart:io';
void main() async {
final server = await HttpServer.bind(InternetAddress.loopbackIPv4, 9001);
print("Servidor JSON en http://localhost:9001");
await for (HttpRequest request in server) {
final path = request.uri.path;
final characters = await loadCharacters();
if (request.method == 'GET' && path == '/characters') {
_sendJson(request, characters);
continue;
}
if (request.method == 'GET' && path.startsWith('/characters/')) {
final idStr = path.split('/').last;
final id = int.tryParse(idStr);
if (id == null) {
_sendJson(request, {"error": "ID inválido"}, status: 400);
continue;
}
final character = findById(characters, id);
if (character == null) {
_sendJson(request, {"error": "Personaje no encontrado"}, status: 404);
} else {
_sendJson(request, character);
}
continue;
}
_sendJson(request, {
"error": "Ruta no encontrada",
"url_lista": "http://localhost:9001/characters",
"url_personaje": "http://localhost:9001/characters/1"
}, status: 404);
}
}
Future<List<Map<String, Object?>>> loadCharacters() async {
final file = File('data.json');
final content = await file.readAsString();
final List<dynamic> jsonData = jsonDecode(content);
return jsonData.cast<Map<String, Object?>>();
}
Map<String, Object?>? findById(List<Map<String, Object?>> list, int id) {
for (final item in list) {
if (item["id"] == id) return item;
}
return null;
}
void _sendJson(HttpRequest request, Object data, {int status = 200}) {
request.response.statusCode = status;
request.response.headers.contentType = ContentType.json;
request.response.write(jsonEncode(data));
request.response.close();
}
run the project / start the server
dart run api.dart
👉 visit:
http://localhost:9001/characters
To test URL sanitization:
http://localhost:9001/characters/1
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