feat: Enhance LanguageMiddleware with improved language detection and validation

- Added support for multiple language detection sources in LanguageMiddleware:
  query parameters (`?lang=xx`), user profile preference, cookies, and Accept-Language header.
- Introduced `LISAN_ALLOWED_LANGUAGES` setting to restrict accepted languages to a configurable list.
- Fallback to `LISAN_DEFAULT_LANGUAGE` when no valid language is detected or if the requested language is not supported.
- Improved parsing of the Accept-Language header to handle complex cases (e.g., "en-US,en;q=0.9").
- Ensured safe retrieval of user profile language preferences to avoid potential errors.
- Added validation to ensure selected language is within supported languages.
- Updated default behavior to gracefully handle missing or malformed headers and attributes.

Author: Nabute

CHANGELOG.md

@@ -1,3 +1,31 @@
+## [v0.1.2] - 2024-10-05
+
+This release focuses on refining the multilingual handling capabilities by introducing additional flexibility in language detection and ensuring compatibility with supported languages.
+
+### Added
+- **Enhanced Language Detection in Middleware**:
+  - **Improved `LanguageMiddleware`**: The `LanguageMiddleware` now includes more robust language detection mechanisms:
+    - It checks for the `lang` query parameter, user profile language preference, cookies, and the `Accept-Language` header in a prioritized manner.
+    - Added support for configurable fallback languages via the `LISAN_DEFAULT_LANGUAGE` setting.
+    - Introduced validation to ensure the selected language is within the list of supported languages, using the new `LISAN_ALLOWED_LANGUAGES` setting.
+    - Refined the `Accept-Language` header parsing to handle complex header values and gracefully fallback when necessary.
+  
+  - **Support for Configurable Allowed Languages**: A new setting, `LISAN_ALLOWED_LANGUAGES`, has been added to specify the languages supported by the application. If a language from the request is not in this list, the middleware falls back to the default language.
+  
+### Configuration Changes
+- **New Settings**:
+  - `LISAN_ALLOWED_LANGUAGES`: A list of language codes that the application supports. The `LanguageMiddleware` ensures that only these languages are applied to the request. Defaults to `[LISAN_DEFAULT_LANGUAGE]`.
+
+### Fixed
+- Improved robustness in the `LanguageMiddleware` by ensuring safe access to user profile attributes and handling of missing or malformed `Accept-Language` headers.
+- Prevented invalid language codes from being set on requests by validating against the new `LISAN_ALLOWED_LANGUAGES` setting.
+
+### Migration Notes
+No database migrations are required for this release. However, to take advantage of the new language validation features, developers should define `LISAN_ALLOWED_LANGUAGES` in `settings.py`.
+
+---
+
+
 ## [v0.1.1] - 2024-09-14
 
 This version brings enhanced flexibility, making the `lisan` package highly adaptable for multilingual projects by enabling external services for automated translations while maintaining a customizable architecture.

lisan/middleware.py

@@ -1,4 +1,5 @@
 from django.utils.deprecation import MiddlewareMixin
+from django.conf import settings
 
 
 class LanguageMiddleware(MiddlewareMixin):
@@ -24,11 +25,49 @@ def process_request(self, request):
         Args:
             request: The HTTP request object.
         """
+        # Fetch the default language from settings, fallback to 'en'
+        default_language = getattr(settings, 'LISAN_DEFAULT_LANGUAGE', 'en')
+        supported_language = getattr(settings, 'LISAN_ALLOWED_LANGUAGES', [default_language])
+        
+        # Safe retrieval of user profile language preference
+        language_preference = None
+        if hasattr(request, 'user') and hasattr(request.user, 'profile') and hasattr(request.user.profile, 'language_preference'):
+            language_preference = request.user.profile.language_preference
+
+        # Extract the language code in order of precedence
         language_code = (
             request.GET.get('lang') or
-            getattr(request.user, 'profile.language_preference', None) or
+            language_preference or
             request.COOKIES.get('language') or
-            request.headers.get('Accept-Language') or
-            'en'
+            self.parse_accept_language(request.headers.get('Accept-Language')) or
+            default_language
         )
+
+        # Validate against supported languages
+        if language_code not in supported_language:
+            language_code = default_language
+
+        # Set the language code on the request object
         request.language_code = language_code
+
+    def parse_accept_language(self, accept_language_header):
+        """
+        Parse the 'Accept-Language' header and extract the first language code.
+        If the header is malformed or empty, return None.
+
+        Args:
+            accept_language_header: The value of the 'Accept-Language' header.
+
+        Returns:
+            A string representing the best matched language code, or None if not found.
+        """
+        if not accept_language_header:
+            return None
+
+        # Split on commas and take the first part before any semicolon
+        languages = accept_language_header.split(',')
+        if languages:
+            primary_language = languages[0].split(';')[0].strip()
+            return primary_language if primary_language else None
+        
+        return None

setup.py

@@ -11,7 +11,7 @@ def read_file(filename):
 
 setup(
     name='lisan',
-    version='0.1.1',
+    version='0.1.2',
     packages=find_packages(),
     include_package_data=True,
     license='MIT',