Support Explicitly Excluding Locales From Smartling Sync

[dchukhin]

This pull request makes it possible to explicitly exclude locales from syncing to Smartling by setting EXCLUDE_LOCALES in the WAGTAIL_LOCALIZE_SMARTLING setting.
Any locales defined in Job.get_or_create_from_source_and_translation_data() are excluded prior to looking for existing jobs or creating a new job.

[Copilot]

Pull request overview

Adds a new WAGTAIL_LOCALIZE_SMARTLING["EXCLUDE_LOCALES"] setting to prevent specific Wagtail locales from entering the Smartling job pipeline, and validates/uses it during job creation.

Changes:

• Introduces EXCLUDE_LOCALES on SmartlingSettings with validation against WAGTAIL_CONTENT_LANGUAGES.
• Filters excluded-locale translations inside Job.get_or_create_from_source_and_translation_data() (including a no-op return when all translations are excluded).
• Adds unit tests and README documentation for the new setting.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/wagtail_localize_smartling/settings.py	Adds EXCLUDE_LOCALES setting + validation during settings initialization.
src/wagtail_localize_smartling/models.py	Filters out excluded locales before job lookup/creation.
tests/test_settings.py	Adds settings validation tests for EXCLUDE_LOCALES.
tests/test_models.py	Adds job-creation behavior tests for excluded locales.
README.md	Documents how to configure EXCLUDE_LOCALES and what it does.

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[Copilot]

The error message here says EXCLUDE_LOCALES must be a "list, tuple, or set", but the code also accepts a frozenset. Update the message to match the accepted types (and consider saying it must be an iterable of locale code strings).

Suggested change

	f"{setting_name}['EXCLUDE_LOCALES'] must be a list, tuple, or set "
	f"of locale code strings"
	f"{setting_name}['EXCLUDE_LOCALES'] must be an iterable "
	f"(list, tuple, set, or frozenset) of locale code strings"

[Copilot]

invalid_codes = set(exclude) - valid_locale_codes will raise a TypeError if EXCLUDE_LOCALES contains any unhashable items (e.g. a nested list) and currently doesn't validate that each entry is a string. Consider explicitly validating each element is a str (and rejecting non-hashable values) so misconfiguration consistently raises ImproperlyConfigured with a clear message instead of crashing during settings init.

Suggested change

	valid_locale_codes = {
	code
	for code, _ in getattr(
	django_settings, "WAGTAIL_CONTENT_LANGUAGES", []
	)
	}
	invalid_codes = set(exclude) - valid_locale_codes
	if invalid_codes:
	raise ImproperlyConfigured(
	f"{setting_name}['EXCLUDE_LOCALES'] contains locale codes not in "
	f"WAGTAIL_CONTENT_LANGUAGES: {sorted(invalid_codes)}"
	)
	settings_kwargs["EXCLUDE_LOCALES"] = frozenset(exclude)
	# Validate that each entry is a string so we can safely use it in a set
	exclude_codes: list[str] = []
	for value in exclude:
	if not isinstance(value, str):
	raise ImproperlyConfigured(
	f"{setting_name}['EXCLUDE_LOCALES'] must contain only strings; "
	f"got {value!r} (type {type(value).__name__})"
	)
	exclude_codes.append(value)
	valid_locale_codes = {
	code
	for code, _ in getattr(
	django_settings, "WAGTAIL_CONTENT_LANGUAGES", []
	)
	}
	invalid_codes = set(exclude_codes) - valid_locale_codes
	if invalid_codes:
	raise ImproperlyConfigured(
	f"{setting_name}['EXCLUDE_LOCALES'] contains locale codes not in "
	f"WAGTAIL_CONTENT_LANGUAGES: {sorted(invalid_codes)}"
	)
	settings_kwargs["EXCLUDE_LOCALES"] = frozenset(exclude_codes)

[Copilot]

This filtering/logging uses t.target_locale.language_code, which will trigger an extra DB query per Translation if translations is a queryset without select_related('target_locale') (e.g. job.translations.all() in the resubmit view). Consider ensuring locales are fetched in bulk (e.g. select_related when possible) or restructuring to use target_locale_id plus a single Locale lookup, to avoid N+1 queries when excluding locales.

Suggested change

	excluded_translations = [t for t in translations_list if t.target_locale.language_code in excluded]
	if excluded_translations:
	logger.info(
	"Excluding %d translation(s) for locales: %s",
	len(excluded_translations),
	", ".join(t.target_locale.language_code for t in excluded_translations),
	)
	translations_list = [t for t in translations_list if t.target_locale.language_code not in excluded]
	# Bulk-load locales to avoid N+1 queries on t.target_locale
	target_locale_ids = {
	t.target_locale_id for t in translations_list if getattr(t, "target_locale_id", None)
	}
	locales_by_id = Locale.objects.in_bulk(target_locale_ids) if target_locale_ids else {}
	def _is_excluded(translation: Translation) -> bool:
	locale = locales_by_id.get(getattr(translation, "target_locale_id", None))
	return bool(locale and locale.language_code in excluded)
	excluded_translations = [t for t in translations_list if _is_excluded(t)]
	if excluded_translations:
	excluded_language_codes = sorted(
	{
	locales_by_id[t.target_locale_id].language_code
	for t in excluded_translations
	if getattr(t, "target_locale_id", None) in locales_by_id
	}
	)
	logger.info(
	"Excluding %d translation(s) for locales: %s",
	len(excluded_translations),
	", ".join(excluded_language_codes),
	)
	translations_list = [t for t in translations_list if not _is_excluded(t)]

[stevejalim]

Approved with comments (r+wc)

@dchukhin I'm going to merge this now, to get it out sooner rather than later, but take a look at the optimisation comments from Copilot and if you agree they're worth it, feel free to follow up with another PR.

Thanks for sorting this!

[stevejalim]

Optimisation nit, nonblocking: could this be done more efficiently with a set.difference, I'm wondering