marshmallow-i18n-messages

A simple library to provide i18n messages for marshmallow validation errors.

Installation

pip install marshmallow-i18n-messages

Usage

Call add_i18n_to_marshmallow once at application startup, before any marshmallow schemas are imported or instantiated:

from marshmallow_i18n_messages import add_i18n_to_marshmallow

add_i18n_to_marshmallow()

After this call all marshmallow validation errors will be translated to the active GNU gettext locale at the moment the error is rendered.

Enabling i18n for schemas loaded before add_i18n_to_marshmallow

If a schema class was imported and cached before add_i18n_to_marshmallow was called, its error messages will not have been wrapped yet. Enable i18n on it explicitly with enable_i18n:

from marshmallow_i18n_messages import enable_i18n

enable_i18n(MyAlreadyLoadedSchema)

enable_i18n is idempotent — calling it on a schema that is already patched is safe and has no effect. It also recurses into parent classes and any nested schemas automatically.

Invenio / InvenioRDM usage

This package ships with an integrated support for InvenioRDM repositories and in most cases, no extra configuration is necessary to activate the translations.

This package adds an invenio_config.module entrypoint that is loaded when InvenioRDM configuration is loaded. This entrypoint:

• Calls add_i18n_to_marshmallow(lazy_gettext) with the lazy_gettext from invenio_i18n
• Registers an app_loaded signal. In this signal it processes marshmallow schemas from all registered invenio services which might have been already cached before the add_i18n_to_marshmallow was called.

If you encounter a schema that is neither covered by the global patch above nor by the built-in service-schema finalizer, patch it explicitly in invenio.cfg:

from mypackage import MyUncoveredSchema
from marshmallow_i18n_messages import enable_i18n
from invenio_i18n import lazy_gettext

enable_i18n(MyUncoveredSchema, lazy_gettext)

If you find such a gap in the built-in coverage, please open an issue so it can be addressed in a future release.

Contributing new translations

To contribute new translations or fix translation issues:

1. Fork the repository and create a feature branch.
2. Add your language to build.sh and create an empty messages.po file at marshmallow_i18n_messages/translations/<language>/LC_MESSAGES/messages.po.
3. Run build.sh to regenerate the POT template and merge it into your PO file.
4. Translate the messages in the generated .po file.
5. Run build.sh again to compile the translations.
6. Commit the changes, push to your fork, and open a pull request.