Language Service

The i18n system in UnPisPas is built around JSON translation files loaded per module, with placeholder-based string interpolation and per-language caching.

import { languageService, languageSupport, langsPath } from '@unpispas/upp-base';

langsPath token

Applications must provide the langsPath injection token to tell the language system where to find JSON files:

import { langsPath } from '@unpispas/upp-base';

@NgModule({
  providers: [
    { provide: langsPath, useValue: '/assets/langs' }
  ]
})
export class AppModule {}

Translation files are expected at {langsPath}/{module}/{language}.json, e.g. /assets/langs/main/es.json.

Supported locales

Code	Language	Flag
ES	Spanish	🇪🇸
EU	Basque	🇪🇸 (PV)
EN	English	🇬🇧
ZH	Chinese	🇨🇳

languageService

The root-level injectable that manages all loaded languages and modules.

Constructor behaviour

1. Detects browser language (navigator.language).
2. Falls back to AppConstants.defaultLanguage ('es') if not supported.
3. Checks URL query parameter ?lang=XX to override.
4. Loads the 'base' translation module on startup.

Methods

Method	Signature	Description
GetLanguages()	(): string[]	Returns supported language codes (for example ES, EN).
FlagFor(language)	(language: string): string | null	Returns the flag icon code for a supported language (for example GB for EN), or null if the code is not in GetLanguages().
GetLanguage(toUpper?)	(toUpper?: boolean): string	Returns the current language code.
SetLanguage(language, global?)	(language: string, global?: boolean): Promise<boolean>	Switches the active language. If global is true (default), all components are notified.
LoadModule(name)	(name: string): Promise<boolean>	Loads a translation module (e.g. 'main', 'guest') in all initialised languages. Emits OnSetLanguage on success.
tr(id, args?, language?)	(id: string, args?: Array<string|number|null|undefined>, language?: string|null): string	Translates a string ID, replacing {{placeholder}} tokens with positional arguments. Returns '...' while loading.
StrInfo(id)	(id: string): { tr: string, args: any[] } | null	Returns raw translation info for a string ID (used by languageSupport).

Observables

Observable	Description
OnSetLanguage	Emits when the language changes or a new module finishes loading.

Translation file format

Each JSON file is an array of translation entries:

[
  { "id": "@loading_wait", "tr": "Cargando, espere...", "args": [] },
  { "id": "@http_request_error", "tr": "Error en la solicitud HTTP: {{status}}", "args": ["status"] }
]

• id: unique string key, conventionally prefixed with @.
• tr: translated text with {{argName}} placeholders.
• args: ordered list of placeholder names matching {{…}} tokens.

---

languageSupport

A utility base class designed to be extended by Angular components that need reactive translations. It handles subscription to language changes and provides per-component translation caching.

import { languageSupport } from '@unpispas/upp-base';

export class MyComponent extends languageSupport implements OnDestroy {
  constructor(lang: languageService, chng: ChangeDetectorRef) {
    super(lang, chng);
  }

  ngOnDestroy() {
    super.OnDestroy();
  }
}

Properties

Property	Type	Description
language	string | null	Currently active language for this component.

Methods

Method	Signature	Description
tr(id, args?)	(id: string, args?: any[]): string	Translates with per-component caching. Zero-arg translations are cached in a Map; translations with args use a separate cache keyed by string ID.
SetLanguage(language)	(language: string): Promise<void>	Switches this component's language without affecting the global setting (useful for bilingual receipts).
OnDestroy()	(): void	Unsubscribes from language-change notifications. Must be called in the component's ngOnDestroy.

How caching works

1. Translations with no arguments are stored in _strcache (Map<id, string>).
2. Translations with arguments are stored in _argcache (Map<id, trinfo>) for the template, then resolved with the provided args.
3. When the language changes, both caches are cleared and ChangeDetectorRef.detectChanges() is called.

Usage example

export class TicketComponent extends languageSupport implements OnDestroy {
  constructor(private lang: languageService, private cdr: ChangeDetectorRef) {
    super(lang, cdr);
  }

  get title(): string {
    return this.tr('@ticket_title');
  }

  get errorMessage(): string {
    return this.tr('@http_request_error', [404]);
  }

  ngOnDestroy() {
    super.OnDestroy();
  }
}