Table of Contents

Localization

PolarSharp ships built-in localization for en-US (default) and es-MX. All user-facing error messages, webhook errors, and toast notification strings are fully translated in both cultures out of the box — zero configuration required.

How it works

PolarSharp resolves strings via IPolarLocalizer, which wraps IStringLocalizer<PolarMessages> backed by embedded .resx satellite assemblies.

CultureInfo.CurrentUICulture at the time of each string lookup determines which language is returned. ASP.NET Core's UseRequestLocalization middleware sets this from the Accept-Language header (or query string / route).

Enabling additional cultures

In Program.cs:

app.UseRequestLocalization(opts =>
    opts.SetDefaultCulture("en-US")
        .AddSupportedUICultures("en-US", "es-MX", "fr-FR"));

PolarSharp will use en-US as the fallback for fr-FR until French .resx files are added.

Custom localizer

To replace the built-in strings entirely (database-backed, translation API, etc.), register your own IPolarLocalizer before calling AddPolarInfrastructure:

services.AddSingleton<IPolarLocalizer, MyDatabaseLocalizer>();
services.AddPolarInfrastructure(builder.Configuration);

The TryAddSingleton pattern ensures the built-in implementation is not registered when a custom one already exists.

Adding a new language

  1. Copy src/PolarSharp/Localization/Resources/PolarMessages.resx to PolarMessages.fr-FR.resx
  2. Translate all values (keys must be identical — see PolarMessageKeys.cs for the full list)
  3. Do the same for src/PolarSharp.Webhooks/Localization/Resources/PolarWebhookMessages.fr-FR.resx
  4. Run the CI test AllMessageKeys_PresentIn_Resx("fr-FR") — it will fail until all keys are translated

The CI test catches any key added to PolarMessageKeys.cs that is missing from any supported .resx file.

Available localization keys

All keys are defined in PolarMessageKeys (core) and PolarWebhookMessageKeys (webhooks). Examples:

Key en-US es-MX
Error_Unauthorized Authentication failed. Verify your Polar access token. Error de autenticación. Verifique su token de acceso de Polar.
Error_NotFound The requested resource was not found. El recurso solicitado no fue encontrado.
Webhook_SignatureInvalid Webhook signature verification failed. La verificación de firma del webhook falló.
Toast_order_created_Title New Order Nuevo Pedido

Testing localization

Use GET /test/localization/errors?culture=es-MX in PolarTestApp to verify that a given culture returns the correct translations.

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