Define. Get. Set. Done.

No boilerplate. No repeated strings. No setup. Define your variables once, then get() and set() them anywhere with zero friction. prf makes local persistence faster, simpler, and easier to scale.

Supports more types than SharedPreferences out of the box — including DateTime, Uint8List, enums, and full JSON.

• Introduction
• Why Use prf?
• SharedPreferences vs prf
• Setup & Basic Usage (Step-by-Step)
• Available Methods for All prf Types
• Supported prf Types
• Roadmap & Future Plans
• Why prf Wins in Real Apps

⚡ Define → Get → Set → Done

Just define your variable once — no strings, no boilerplate:

final username = PrfString('username');

Then get it:

final value = await username.get();

Or set it:

await username.set('Joey');

That’s it. You're done.

Works with: int, double, bool, String, List<String>,
and advanced types like DateTime, Uint8List, enums, and full JSON objects.

---

🔥 Why Use prf

Working with SharedPreferences often leads to:

• Repeated string keys
• Manual casting and null handling
• Verbose async boilerplate
• Scattered, hard-to-maintain logic

prf solves all of that with a one-line variable definition that’s type-safe, cached, and instantly usable throughout your app. No key management, no setup, no boilerplate, no .getString(...) everywhere.

---

What Sets prf Apart?

• ✅ Single definition — just one line to define, then reuse anywhere
• ✅ Type-safe — no casting, no runtime surprises
• ✅ Automatic caching — values are stored in memory after the first read
• ✅ Lazy initialization — no need to manually call SharedPreferences.getInstance()
• ✅ Supports more than just primitives
  • String, int, double, bool, List<String>
  • DateTime, Uint8List, enums, and full JSON objects
• ✅ Built for testing — easily reset or mock storage in tests
• ✅ Cleaner codebase — no more scattered prefs.get...() or typo-prone string keys

---

🔁 SharedPreferences vs prf

Feature	SharedPreferences (raw)	prf
Define Once, Reuse Anywhere	❌ Manual strings everywhere	✅ One-line variable definition
Type Safety	❌ Requires manual casting	✅ Fully typed, no casting needed
Readability	❌ Repetitive and verbose	✅ Clear, concise, expressive
Centralized Keys	❌ You manage key strings	✅ Keys are defined as variables
Caching	❌ No built-in caching	✅ Automatic in-memory caching
Lazy Initialization	❌ Must await getInstance() manually	✅ Internally managed
Supports Primitives	✅ Yes	✅ Yes
Supports Advanced Types	❌ No (DateTime, enum, etc. must be encoded manually)	✅ Built-in support for DateTime, Uint8List, enum, JSON

📌 Code Comparison

Using SharedPreferences:

final prefs = await SharedPreferences.getInstance();
await prefs.setString('username', 'Joey');
final username = prefs.getString('username') ?? '';

Using prf:

final username = PrfString('username');
await username.set('Joey');
final name = await username.get();

If you're tired of:

• Duplicated string keys
• Manual casting and null handling
• Scattered boilerplate

Then prf is your drop-in solution for fast, safe, scalable, and elegant local persistence.

🚀 Setup & Basic Usage (Step-by-Step)

Step 1: Add prf to your pubspec.yaml

dependencies:
  prf: ^latest

Then run:

flutter pub get

---

Step 2: Define Your Variable

You only need one line to create a saved variable.
For example, to save how many coins a player has:

final playerCoins = PrfInt('player_coins', defaultValue: 0);

This means:

• You're saving an int (number)
• The key is 'player_coins'
• If it's empty, it starts at 0

---

Step 3: Save a Value

To give the player 100 coins:

await playerCoins.set(100);

---

Step 4: Read the Value

To read how many coins the player has:

final coins = await playerCoins.get();
print('Coins: $coins'); // 100

That’s it! 🎉 You don’t need to manage string keys or setup anything. Just define once, then use anywhere in your app.

🧰 Available Methods for All prf Types

Method	Description
get()	Returns the current value (cached or from disk).
set(value)	Saves the value and updates the cache.
remove()	Deletes the value from storage and memory.
isNull()	Returns true if the value is null.
getOrFallback(fallback)	Returns the value or a fallback if null.
existsOnPrefs()	Checks if the key exists in SharedPreferences.

Available on all prf types — consistent, type-safe, and ready anywhere in your app.

🔤 Supported prf Types

Define your variable once with a type that fits your use case. Every type supports .get(), .set(), .remove(), and more — all cached, type-safe, and ready to use.

Type	Class	Common Use Cases
bool	PrfBool	Feature flags, settings toggles
int	PrfInt	Counters, scores, timestamps
double	PrfDouble	Ratings, sliders, precise values
String	PrfString	Usernames, tokens, IDs
List<String>	PrfStringList	Tags, recent items, multi-select options
Uint8List	PrfBytes	Binary data (images, keys, QR codes)
DateTime	PrfDateTime	Timestamps, cooldowns, scheduled actions
enum	PrfEnum<T>	Typed modes, states, user roles
T (via JSON)	PrfJson<T>	Full model objects with toJson / fromJson

✅ All Types Support:

• get() – read the current value (cached or from disk)
• set(value) – write and cache the value
• remove() – delete from disk and cache
• isNull() – check if null
• getOrFallback(default) – safely access with fallback
• existsOnPrefs() – check if a key is stored

🧠 Custom Types? No Problem

Want to persist something more complex? Use PrfJson<T> with any model that supports toJson and fromJson.

final userData = PrfJson<User>(
  'user',
  fromJson: (json) => User.fromJson(json),
  toJson: (user) => user.toJson(),
);

Or use PrfEncoded<TSource, TStore> to define your own encoding logic (e.g., compress/encrypt/etc).

🛣️ Roadmap & Future Plans

prf is built for simplicity, performance, and scalability. Upcoming improvements focus on expanding flexibility while maintaining a zero-boilerplate experience.

✅ Planned Enhancements

• Improved performance
  Smarter caching and leaner async operations.

• Additional type support
  Duration, BigInt, encrypted strings, and enhanced PrfJson<T>.

• Custom storage (experimental)
  Support for alternative adapters (Hive, Isar, file system).

• Testing & tooling
  In-memory test adapter, debug inspection tools, and test utilities.

• Optional code generation
  Annotations for auto-registering variables and reducing manual setup.

🔍 Why prf Wins in Real Apps

Working with SharedPreferences directly can quickly become verbose, error-prone, and difficult to scale. Whether you’re building a simple prototype or a production-ready app, clean persistence matters.

❌ The Problem with Raw SharedPreferences

Even in basic use cases, you're forced to:

• Reuse raw string keys (risk of typos and duplication)
• Manually cast and fallback every read
• Handle async boilerplate (getInstance) everywhere
• Encode/decode complex types manually
• Spread key logic across multiple files

Let’s see how this unfolds in practice.

---

👎 Example: Saving and Reading Multiple Values

Goal: Save and retrieve a username, isFirstLaunch, and a signupDate.

SharedPreferences (verbose and repetitive)

final prefs = await SharedPreferences.getInstance();

// Save values
await prefs.setString('username', 'Joey');
await prefs.setBool('is_first_launch', false);
await prefs.setString(
  'signup_date',
  DateTime.now().toIso8601String(),
);

// Read values
final username = prefs.getString('username') ?? '';
final isFirstLaunch = prefs.getBool('is_first_launch') ?? true;
final signupDateStr = prefs.getString('signup_date');
final signupDate = signupDateStr != null
  ? DateTime.tryParse(signupDateStr)
  : null;

🔻 Issues:

• Repeated string keys — no compile-time safety
• Manual fallback handling and parsing
• No caching — every .get hits disk
• Boilerplate increases exponentially with more values

---

✅ Example: Same Logic with prf

final username = PrfString('username');
final isFirstLaunch = PrfBool('is_first_launch', defaultValue: true);
final signupDate = PrfDateTime('signup_date');

// Save
await username.set('Joey');
await isFirstLaunch.set(false);
await signupDate.set(DateTime.now());

// Read
final name = await username.get();         // 'Joey'
final first = await isFirstLaunch.get();   // false
final date = await signupDate.get();       // DateTime instance

💡 Defined once, used anywhere — fully typed, cached, and clean.

---

🤯 It Gets Worse with Models

Storing a User model in raw SharedPreferences requires:

1. Manual jsonEncode / jsonDecode
2. Validation on read
3. String-based key tracking

SharedPreferences with Model:

final prefs = await SharedPreferences.getInstance();

final json = jsonEncode(user.toJson());
await prefs.setString('user_data', json);

// Read
final raw = prefs.getString('user_data');
User? user;
if (raw != null) {
  try {
    final decoded = jsonDecode(raw);
    user = User.fromJson(decoded);
  } catch (_) {
    // fallback or error
  }
}

---

✅ Same Logic with prf

final userData = PrfJson<User>(
  'user_data',
  fromJson: User.fromJson,
  toJson: (u) => u.toJson(),
);

// Save
await userData.set(user);

// Read
final savedUser = await userData.get(); // User?

🧠 Fully typed. Automatically parsed. Fallback-safe. Reusable across your app.

---

⚙️ Built for Real Apps

prf was built to eliminate the day-to-day pain of using SharedPreferences in production codebases:

• ✅ Define once — reuse anywhere
• ✅ Clean API — get(), set(), remove(), isNull() for all types
• ✅ Supports advanced types: DateTime, Uint8List, enum, JSON
• ✅ Automatic caching — fast access after first read
• ✅ Test-friendly — easily reset, mock, or inspect values

---

🔗 License MIT © Jozz