{"id":686,"date":"2026-11-04T00:37:35","date_gmt":"2026-11-03T16:37:35","guid":{"rendered":"http:\/\/www.lahomiliadeldomingo.com\/blog\/?p=686"},"modified":"2026-11-04T00:37:35","modified_gmt":"2026-11-03T16:37:35","slug":"how-to-create-a-module-in-dart-45c9-f9876b","status":"publish","type":"post","link":"http:\/\/www.lahomiliadeldomingo.com\/blog\/2026\/11\/04\/how-to-create-a-module-in-dart-45c9-f9876b\/","title":{"rendered":"How to create a module in Dart?"},"content":{"rendered":"

Hey there, fellow devs! ???? It\u2019s Javi, from the module squad over here\u2014been building and shipping Dart modules for clients big and small for like 4 years now, and I get it. When you\u2019re juggling a Dart project, piecing together a messy app, or trying to stop rewriting the same old API logic, modules are your bread and butter. But let\u2019s be real: Dart\u2019s module system can feel weirdly jumbled if you\u2019re new, especially if you\u2019re used to how JS or Python does it. No cap, I\u2019ve had 3 devs this week DMing me, \u201cJavi, how do I actually make a usable Dart module without it turning into a mess?\u201d So I\u2019m gonna break this down like I explain it to my interns\u2014no fancy jargon, just real, actionable steps, plus why using a pre-built, maintained module from a supplier like us saves you so much headache later. Module<\/a><\/p>\n

<\/p>\n

First, let\u2019s hit the basics quick\u2014what even is<\/em> a Dart module? Old Dart (before 2.12) had \u201cpackages\u201d and \u201clibraries,\u201d but now it\u2019s all \u201cmodules\u201d tied to Dart\u2019s official package system, right? A module\u2019s just a set of related code\u2014like a auth handler, a payment widget, whatever\u2014that you can drop into any Dart project (Flutter or vanilla Dart server-side) without copying-pasting 100 files. The key here is: a good module is self-contained, has clear docs, and doesn\u2019t fight with your project\u2019s versions. I\u2019ve seen so many devs build a module, then accidentally lock their whole app to an old Dart SDK, and that\u2019s a whole nightmare. Let\u2019s avoid that.<\/p>\n

Step 1: Pick Your Module\u2019s Purpose (Don\u2019t Overcomplicate It)<\/h3>\n

Before you code a single line, stop. Ask: \u201cWhat problem am I solving here?\u201d I\u2019ve seen people spend 2 weeks building a \u201cuniversal data module\u201d that does nothing well because they tried to cram 5 features into it. For example: if you\u2019re making a module for a e-commerce app, don\u2019t build one that handles inventory, payments, and<\/em> user reviews. Build a payment_processor<\/code> module first, then a review_manager<\/code> later. That\u2019s how we do it at the module supplier we work with\u2014we split modules by use case so they\u2019re tiny, testable, and easy to swap out.<\/p>\n

Rule of thumb: Your module should do 1 thing, and do it well. If it\u2019s longer than 500 lines of code, split it into sub-modules (more on that in a sec). For this example, let\u2019s say we\u2019re building a user_auth<\/code> module\u2014handles login, signup, password reset for Flutter\/Dart apps. No extra fluff.<\/p>\n

Step 2: Set Up Your Dart Project Structure (The Right Way)<\/h3>\n

Okay, time to actually make the module. Dart uses pub.dev<\/code> as its package hub, so every module is a Dart package\u2014if you\u2019ve done a Flutter package before, this is familiar, but let\u2019s walk through it.<\/p>\n

First, open your terminal (no VS Code clicks necessary, I promise). Run this:<\/p>\n

dart create --template package user_auth\n<\/code><\/pre>\n
That spits out a folder named user_auth<\/code> with all the default files. Now let\u2019s clean it up a little\u2014delete the test\/<\/code> folder for a sec (we\u2019ll come back to testing later, don\u2019t panic) and edit the pubspec.yaml<\/code> file. This is the config file that tells Dart what your module is called, its version, dependencies, and all that.<\/p>\n
Make sure your pubspec.yaml<\/code> looks like this (no, don\u2019t copy-paste blindly, adjust the names):<\/p>\n
name: user_auth\ndescription: A simple Dart\/Flutter module for email\/password auth and password resets\nversion: 1.0.0\nenvironment:\n  sdk: '>=3.0.0 <4.0.0' # Supports Dart 3+, which is basically all modern projects\ndependencies:\n  # We don\u2019t need extra junk here\u2014just the minimum stuff\n  crypto: ^3.0.3 # For hashing passwords, duh\n  flutter: # If it\u2019s a Flutter module, add this\n    sdk: flutter\ndev_dependencies:\n  test: ^1.24.0\n  lints: ^2.0.0 # Keeps your code clean, no messy formatting\n<\/code><\/pre>\n
Here\u2019s the big thing I drill into every dev I work with: don\u2019t add dependencies you don\u2019t need. If your user_auth<\/code> module doesn\u2019t use Firebase, don\u2019t add it as a dependency. We\u2019ve had clients come to us with a custom module that had 17 dependencies, half of which they never used\u2014we fix that, and it cuts their app\u2019s build size by 20% overnight. Wild.<\/p>\n
Next, make your code folder. Inside user_auth\/<\/code>, make a lib\/<\/code> folder (that\u2019s where your module\u2019s public code lives\u2014don\u2019t put stuff there that devs shouldn\u2019t touch). Then add a main file, like user_auth.dart<\/code>. This is the entry point\u2014any function\/ class you export here is what other projects will use. For our auth module, let\u2019s add some basic code:<\/p>\n
\/\/ lib\/user_auth.dart\nimport 'package:crypto\/crypto.dart';\nimport 'dart:convert';\n\nclass AuthService {\n  final String apiUrl; \/\/ Pass your backend URL here when initializing\n\n  AuthService(this.apiUrl);\n\n  \/\/ Hash user password before sending to backend\u2014never send plain text!\n  String hashPassword(String password) {\n    final bytes = utf8.encode(password);\n    return sha256.convert(bytes).toString();\n  }\n\n  \/\/ Basic login function\n  Future<bool> login(String email, String password) async {\n    final hashedPass = hashPassword(password);\n    \/\/ Example API call\u2014replace with your actual backend logic\n    final response = await Uri.parse('$apiUrl\/login')\n        .get(headers: {'Content-Type': 'application\/json', 'email': email, 'password': hashedPass});\n    return response.statusCode == 200;\n  }\n}\n<\/code><\/pre>\n
Wait, hold on\u2014if you\u2019re not a backend dev, or you don\u2019t want to mess with API calls from scratch, that\u2019s exactly why people buy ready-made modules from suppliers like us. We build and test all that core logic so you don\u2019t have to handle edge cases like expired tokens, CORS issues, or password breach checks. Way faster than building from zero.<\/p>\n
Step 3: Make Your Module Usable (No One Wants a Black Box)<\/h3>\n
Here\u2019s where 90% of custom modules fail: they\u2019re a bunch of hidden functions with no docs. If another dev can\u2019t figure out how to call your login<\/code> function, your module is useless. Dart has a built-in way to add docs\u2014just type \/\/\/<\/code> before any class or function, and it\u2019ll show up in pub.dev\u2019s docs.<\/p>\n
Add docs to your AuthService<\/code> so other devs know what it does:<\/p>\n
\/\/\/ A service to handle user authentication for Dart\/Flutter apps.\n\/\/\/ \n\/\/\/ Example usage:\n\/\/\/ ```dart\n\/\/\/ final auth = AuthService('https:\/\/your-backend.com\/api');\n\/\/\/ final isLoggedIn = await auth.login('user@example.com', 'mypassword123');\n\/\/\/ ```\nclass AuthService {\n  \/\/\/ The backend API URL used for auth requests.\n  final String apiUrl;\n\n  \/\/\/ Creates an [AuthService] with your backend [apiUrl].\n  AuthService(this.apiUrl);\n\n  \/\/\/ Hashes a plain text [password] using SHA-256 for secure API transmission.\n  String hashPassword(String password) {\n    \/\/ same code as before\n  }\n\n  \/\/\/ Attempts to log in a user with [email] and [password].\n  \/\/\/ Returns `true` if login succeeds, `false` otherwise.\n  Future<bool> login(String email, String password) async {\n    \/\/ same code as before\n  }\n}\n<\/code><\/pre>\n
See that? Any dev using your module can just hover over AuthService<\/code> in VS Code and see the example code. That\u2019s non-negotiable. If you cut docs, your module will collect dust in some pub.dev folder, no one will use it.<\/p>\n
Also, add a README.md<\/code> file to your module\u2019s root\u2014this is what shows up on pub.dev\u2019s page for your module. It should have:<\/p>\n