Files
summercms/docs/services/localization.md
Jakub Zych b2ce986604 feat(14.2.1-01): add optional surf LocaleResolver seam
Look up a backpack-published resolver so a compiled translate plugin can
strip an enabled URL prefix and write a validated locale onto context.

Co-authored-by: Cursor <cursoragent@cursor.com>
2026-10-06 11:54:00 +02:00

85 lines
4.9 KiB
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---
title: Localization
description: Ship plugin translations in lang YAML catalogs, translate with :name placeholders and CLDR plurals through phrasebook, and read the request locale.
section: services
order: 80
---
# Localization
WinterCMS plugins keep their strings in `lang/<locale>/*.php` and read them with `Lang::get('acme.blog::lang.posts.title')` and `trans_choice`. SummerCMS keeps the key form and Laravel's message syntax; [phrasebook](../../modules/phrasebook/README.md) loads the catalogs and translates.
## Catalogs
A plugin ships `lang/<locale>/<group>.yaml` files and implements `pact.HasLang` to return them. Nested maps flatten into dotted keys under the plugin ID, so `title` in `lang/en/posts.yaml` of `acme.blog` is the key `acme.blog::posts.title`. At boot, `phrasebook.Activate` loads the framework strings and every plugin's catalogs and publishes one `phrasebook.Translator` on the application. Duplicate keys, malformed paths and values that are not strings fail the start-up.
A plugin that implements `pact.HasLangOverrides` can replace keys of any loaded namespace, the framework's admin strings included, with files laid out as `lang/<locale>/<namespace>/<group>.yaml`. Overrides may also add a locale.
## Translating
`phrasebook.Translator.Get` translates a key in the request locale, and `phrasebook.Translator.GetIn` in a locale you name. A lookup tries the locale, then its parent (`pt-BR`, then `pt`), then `app.fallback_locale`. A key that no locale has comes back unchanged, and outside production it is logged once. Placeholders follow Laravel: `:name` inserts the value, `:Name` capitalizes its first letter and `:NAME` upper-cases it:
```go src=modules/phrasebook/example_test.go#ExampleTranslator_Get
cat := phrasebook.NewCatalog()
if err := cat.Load("acme.blog", langFS); err != nil {
fmt.Println(err)
return
}
tr := phrasebook.NewTranslator(cat, phrasebook.Options{Locale: "en", Fallback: "en"})
// surf stores the request locale on the context; here the example does.
ctx := towel.WithLocale(context.Background(), "pl")
fmt.Println(tr.Get(ctx, "acme.blog::posts.title", nil))
// pl has no greeting, so the fallback locale answers.
fmt.Println(tr.Get(ctx, "acme.blog::posts.greeting", map[string]string{"name": "Ada"}))
fmt.Println(tr.GetIn("en", "acme.blog::posts.shout", map[string]string{"name": "Ada"}))
// A missing key comes back as the key.
fmt.Println(tr.Get(ctx, "acme.blog::posts.missing", nil))
// Output:
// Posty
// Hello, Ada
// Welcome, ADA
// acme.blog::posts.missing
```
Application code gets the published translator with `app.Lookup[*phrasebook.Translator]()`.
## Plurals
`phrasebook.Translator.Choice` and `phrasebook.Translator.ChoiceIn` pick a plural form and fill in `:count`. A key can hold a map of CLDR plural categories (`one`, `few`, `many`, `other`, ...), checked against the categories the locale actually has, so a Polish string gets the forms Polish needs. Laravel's pipe syntax works too, with exact (`{0}`) and range (`[2,*]`) conditions:
```go src=modules/phrasebook/example_test.go#ExampleTranslator_Choice
cat := phrasebook.NewCatalog()
if err := cat.Load("acme.blog", langFS); err != nil {
fmt.Println(err)
return
}
tr := phrasebook.NewTranslator(cat, phrasebook.Options{Locale: "en", Fallback: "en"})
for _, n := range []int{1, 3, 5, 22} {
fmt.Println(tr.ChoiceIn("pl", "acme.blog::posts.count", n, nil))
}
fmt.Println(tr.ChoiceIn("en", "acme.blog::posts.count", 5, nil))
for _, n := range []int{0, 1, 7} {
fmt.Println(tr.ChoiceIn("en", "acme.blog::posts.drafts", n, nil))
}
// Output:
// 1 post
// 3 posty
// 5 postów
// 22 posty
// 5 posts
// No drafts
// One draft
// 7 drafts
```
## The request locale
The locale lives on the request context, not in a global. For every route, [surf](../../modules/surf/README.md) looks up an optional `surf.LocaleResolver` published by a compiled plugin and writes that validated code with `towel.WithLocale`. When no resolver is published, surf sets the locale from the `Accept-Language` header and the `locale.from-principal` middleware can switch it to the signed-in user's preferred locale. Code reads it with `towel.Locale`, and code outside a request sets it with `towel.WithLocale`, as the example above does. A context without a locale uses `app.locale`.
## Strings for the admin
The admin SPA receives its strings from the server. `phrasebook.Translator.Bundle` returns every key under a prefix as CLDR plural forms, merged over the fallback chain, and `phrasebook.Translator.Forms` returns one key. Start-up fails if an admin (`backend::`) string cannot be expressed as CLDR forms, so a pipe string with a condition the SPA cannot evaluate is caught before any admin sees it.
The framework ships its validation messages (`lagoon::validate` for `lagoon.Validate`, and the full WinterCMS validator catalog `lagoon::validation` for `lagoon.ValidateRequest`) and admin strings (`backend::lang`) in English and Polish.