Typed Shared Preferences

A type-safe wrapper around shared_preferences, inspired by ts-localstorage.

Why?

• Dart compiler now prevents you from writing a bool to an int key
• You can organize everything related to [SharedPreferences] in one file, not just the string keys
• You don’t need to call SharedPreferences.getInstance() anywhere anymore

Usage

• You create a PrefKey or a PrefKeyNullable, pass a string as a key and a default value that’s returned when the value doesn’t exist in the SharedPreferences.
• In case of PrefKeyNullable, the default value is still required to guarantee type safety, but it’s not actually used anywhere

Check test/shared_preferences_typed_test.dart for a more detailed example, here are the most common use cases:

Basic example (non-nullable)

/// Description
const key = PrefKey("some_key", true);

final valueBefore = await key.read(); // -> true (default value)
await key.write(false); // -> Value is now false

Basic example (nullable)

/// Description
const key = PrefKeyNullable("some_key", true);

final valueBefore = await key.read(); // -> null
await key.write(false); // -> Value is now false

Existing SharedPreferences instance (non-nullable)

final prefs = await SharedPreferences.instance();

/// Description
const key = PrefKey("some_key", true);

final valueBefore = await key.readSync(prefs); // -> true (default value)
await key.write(false); // -> Value is now false

Existing SharedPreferences instance (nullable)

final prefs = await SharedPreferences.instance();

/// Description
const key = PrefKeyNullable("some_key", true);

final valueBefore = await key.readSync(prefs); // -> null
await key.writeSync(false, prefs); // -> Value is now false

Additional information

• Using an existing SharedPreferences instance has no performance gain if you don’t also use it elsewhere. However, the sync methods have benefits when you really can’t have await somewhere.

GitHub

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