Localization (i18n)

Guides you through the steps to internationalize your application to provide localized versions with respect to both Localized Models as well as Localized Data.

‘Localization’ is a means to adapting your app to the languages of specific target markets.

This guide focuses on static texts such as labels. See CDS and Localized Data for information about how to manage and serve actual payload data in different translations.

Content

• Externalizing Texts Bundles
• Where to Place Text Bundles?
• CSV-Based Text Bundles
• Merging Algorithm
• Merging Reuse Bundles
• Determining User Locales
• Normalized Locales

Externalizing Texts Bundles

All you have to do to internationalize your models is to externalize all of your literal texts to text bundles and refer to the respective keys from your models as annotation values. Here is a sample of a model and the corresponding bundle.

srv/my-service.1.cds

service Bookshop {
  entity Books @(
    UI.HeaderInfo: {
      Title.Label: '{i18n>Book}',
      TypeName: '{i18n>Book}',
      TypeNamePlural: '{i18n>Books}',
    },
  ){/*...*/}
}

_i18n/i18n.properties

Book = Book
Books = Books
foo = Foo

You can define the keys of your properties entries.

Learn more about annotations in CSN.

Then you can translate the texts in localized bundles, each with a language/locale code appended to its name, for example:

_i18n/
  i18n.properties           # dev main --› 'default fallback'
  i18n_en.properties        # English    --› 'default language'
  i18n_de.properties        # German
  i18n_zh_TW.properties     # Traditional Chinese
  ...

Where to Place Text Bundles?

By default, text bundles can be placed in, and are fetched from, folders named _i18n,i18n, or_assets/i18n_. These folders are placed next to the model files or in a parent folder as follows:

srv/
   my-service.cds          # the model file
   _i18n/i18n.properties   # next to the model file
_i18n/i18n.properties      # in a parent folder

You can configure the folder names where cds searches for property bundles by setting cds.i18n.folders in your project’s package.json.

The default is:

"cds":{"i18n":{
  "folders": [ "_i18n", "i18n", " assets/i18n" ]
}}

These folders are resolved relative to the working directory of the application.

CSV-Based Text Bundles

For smaller projects you can use CSV files instead of .properties files, which you can easily edit in Excel, Numbers, etc.

The format is as follows:

With this CSV source:

key;en;de;zh_CN;...
Book;Book;Buch;...
Books;Books;Bücher;...
...

Merging Algorithm

Each localized model is constructed by applying:

1. The default fallback bundle (that is, i18n.properties), then …
2. The default language bundle (usually i18n_en.properties), then …
3. The requested bundle (for example, i18n_de.properties)

In that order.

So, the complete stack of overlaid models for the given example would look like this (higher ones override lower ones):

Note
The default language is usually en but can be overridden by configuring cds.i18n.default_language in your project’s package.json.

Merging Reuse Bundles

If your application is importing models from a reuse package, that package comes with its own language bundles for localization. These are applied upon import, so they can be overridden in your models as well as in your language bundles and their translations.

For example, assuming that your data model imports from a foundation package, then the overall stack of overlays would look like this:

Determining User Locales

Upon incoming requests at runtime, the user’s preferred language is determined as follows:

1. Read the preferred language from the first of:
   1. The value of the sap-language URL parameter, if present
   2. A chosen language from the user’s applications settings, if available
   3. A chosen language in the user’s global settings, if available
   4. The first entry from the request’s Accept-Language header
   5. The default language configured on the app level
2. Narrow to normalized locales as described below.

CAP also accepts formats following the available standards of POSIX and RFC 1766, and transforms them into normalized locales.

Normalized Locales

To reduce the number of required translations, most determined locales are normalized by narrowing them to their main language codes only, for example, en_US, en_CA, en_AU → en, except for these allowed language codes:

Due to the ambiguity regarding standards, for example, the usage of hyphens (-) in contrast to underscores (_), CAP follows the approach of the SAP Translation Hub. Using that approach, CAP normalizes locales to underscores as our de facto standard.