Handle if lang code in settings is None

garnett/middleware.py

@@ -1,10 +1,13 @@
 from django.conf import settings
 from django.http import Http404
+from django.utils.module_loading import import_string
 from django.utils.translation import gettext as _
 
 import logging
+import langcodes
+from langcodes import Language
 
-from .utils import get_language_from_request, is_valid_language
+from .utils import is_valid_language, get_default_language
 from .context import set_field_language
 
 logger = logging.getLogger(__name__)
@@ -86,3 +89,31 @@ def __call__(self, request):
             )
 
         return self.get_response(request)
+
+
+def get_language_from_request(request) -> Language:
+    opt_order = getattr(
+        settings,
+        "GARNETT_REQUEST_LANGUAGE_SELECTORS",
+        [
+            "garnett.selectors.header",
+            "garnett.selectors.query",
+            "garnett.selectors.cookie",
+        ],
+    )
+    for opt in opt_order:
+        func = import_string(opt)
+        if lang := func(request):
+            try:
+                return Language.get(lang)
+            except langcodes.tag_parser.LanguageTagError:
+                raise Http404(
+                    _(
+                        "The provided language %(lang_code)s is not a valid language code"
+                    )
+                    % {
+                        "lang_code": lang,
+                    }
+                )
+
+    return get_default_language()

garnett/utils.py

@@ -1,7 +1,7 @@
-from typing import List, Union
+from typing import List, Union, Optional
 
+import langcodes.tag_parser
 from django.conf import settings
-from django.utils.module_loading import import_string
 from django.core.exceptions import ImproperlyConfigured
 from langcodes import Language
 
@@ -68,31 +68,42 @@ def get_current_blank_override() -> bool:
     return _ctx_force_blank.get(False)
 
 
+def get_safe_language(lang_code: str) -> Optional[Language]:
+    """Return language if language for lang code exists, otherwise none"""
+    try:
+        return Language.get(lang_code)
+    except langcodes.tag_parser.LanguageTagError:
+        return None
+
+
+def validate_language_list(langs) -> List[Language]:
+    """
+    Validate and clean a potential list of languages.
+    This may return an empty list if the provided languages are invalid
+    """
+    if type(langs) is not list:
+        return []
+
+    languages = []
+    for lang_code in langs:
+        if language := get_safe_language(lang_code):
+            languages.append(language)
+
+    if languages:
+        return languages
+
+
 def get_languages() -> List[Language]:
     langs = getattr(
         settings, "GARNETT_TRANSLATABLE_LANGUAGES", [get_default_language()]
     )
     if callable(langs):
         langs = langs()
-    if type(langs) == list:
-        return [Language.get(lang) for lang in langs]
-    raise ImproperlyConfigured(
-        "GARNETT_TRANSLATABLE_LANGUAGES must be a list or a callable that returns a list"
-    )
 
+    languages = validate_language_list(langs)
 
-def get_language_from_request(request) -> Language:
-    opt_order = getattr(
-        settings,
-        "GARNETT_REQUEST_LANGUAGE_SELECTORS",
-        [
-            "garnett.selectors.header",
-            "garnett.selectors.query",
-            "garnett.selectors.cookie",
-        ],
-    )
-    for opt in opt_order:
-        func = import_string(opt)
-        if lang := func(request):
-            return Language.get(lang)
-    return get_default_language()
+    if not languages:
+        raise ImproperlyConfigured(
+            "GARNETT_TRANSLATABLE_LANGUAGES must be a list of languages or a callable that returns a list of languages"
+        )
+    return languages