LangProvider class abstract

LangProvider contract that defines the interface for a language provider.

The LangProvider contract is used to define the interface for a language provider. The language provider is responsible for providing the translations for the application, with advanced features like pluralization, parameter replacement, and context support.

The LangProvider contract defines the following methods:

  • setLocale: Sets the locale for the language provider.
  • getLocale: Gets the current locale.
  • setFallbackLocale: Sets the fallback locale.
  • t: Translates a key with optional parameters and context.
  • choice: Translates with pluralization based on count.
  • field: Translates a field label.
  • has: Checks if a translation key exists.
  • get: Gets raw translation value.
  • loadNamespace: Loads translations for a namespace (e.g., packages).
  • clearCache: Clears any cached translations.

The t method supports advanced parameter replacement using :param syntax. The choice method handles plural forms based on count. Namespaces allow organizing translations for different packages or modules.

Example Usage

class MyLangProvider implements LangProvider {
  // Implementation here
}

final provider = MyLangProvider();
provider.setLocale('en');
provider.setFallbackLocale('en');

// Basic translation
String greeting = provider.t('messages.greeting');

// Translation with parameters
String welcome = provider.t('messages.welcome', parameters: {'name': 'Alice'});

// Pluralization
String items = provider.choice('items.count', 5, parameters: {'count': 5});

// Field translation
String label = provider.field('email');

// Namespace support
provider.loadNamespace('package:auth', 'en', {'login': 'Sign In'});
String login = provider.t('login', namespace: 'package:auth');

Translation File Structure

Translation files are typically JSON files organized by locale:

lang/
├── en/
│   ├── messages.json
│   └── validation.json
└── fr/
    ├── messages.json
    └── validation.json

Parameter Replacement

Parameters are replaced using :param syntax:

{
  "welcome": "Hello :name, welcome to :app",
  "items": "You have :count item|You have :count items"
}

Pluralization

Use | to separate singular and plural forms:

{
  "apple": "apple|apples",
  "item": "item|items"
}
Implementers

Constructors

LangProvider()

Properties

hashCode → int
The hash code for this object.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

addParameterReplacer(String replacer(String key, dynamic value, Map<String, dynamic> parameters)) → void
Adds a custom parameter replacer function.
choice(String key, int count, {Map<String, dynamic>? parameters, String? locale, String? namespace}) → String
Translates with pluralization based on count.
clearCache() → void
Clears any cached translations.
field(String key, {String? locale, String? namespace}) → String
Translates a field label.
get(String key, {String? locale, String? namespace}) → String?
Gets the raw translation value without parameter replacement.
getAvailableLocales() → List<String>
Gets all available locales.
getFallbackLocale() → String
Gets the fallback locale.
getLocale() → String
Gets the current locale.
has(String key, {String? locale, String? namespace}) → bool
Checks if a translation key exists.
loadNamespace(String namespace, String locale, Map<String, String> translations) → void
Loads translations for a specific namespace.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
setFallbackLocale(String locale) → void
Sets the fallback locale for missing translations.
setLocale(String locale) → void
Sets the locale for the language provider.
t(String key, {Map<String, dynamic>? parameters, String? locale, String? namespace}) → String
Translates a key with optional parameters, context, and namespace.
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited