Django-Translatable-Fields/django_translatable_fields/descriptors.py

import json
from django.utils.translation import get_language


class TranslatableFieldDescriptor:
    """
    Descriptor that provides language-aware access to translatable field values.
    
    Usage:
        class MyModel(models.Model):
            name = TranslatableCharField()
            
        # Access current language value
        obj.name  # Returns value in current language
        
        # Access specific language
        obj.name_en  # Returns English value
        obj.name_de  # Returns German value
        
        # Set values
        obj.name = "Hello"  # Sets for current language
        obj.name_en = "Hello"  # Sets for English
        obj.name_de = "Hallo"  # Sets for German
    """
    
    def __init__(self, field_name):
        self.field_name = field_name
        self.storage_name = f'_{field_name}_translations'
    
    def __get__(self, instance, owner=None):
        if instance is None:
            return self
        
        # Get the stored translations
        raw_value = getattr(instance, self.field_name)
        translations = self._parse_translations(raw_value)
        
        # Return value for current language
        current_lang = get_language()
        if current_lang and current_lang in translations:
            return translations[current_lang]
        
        # Fallback to default language or first available
        if 'en' in translations:
            return translations['en']
        elif translations:
            return next(iter(translations.values()))
        
        return ''
    
    def __set__(self, instance, value):
        if value is None:
            setattr(instance, self.field_name, None)
            return
        
        # Get existing translations
        raw_value = getattr(instance, self.field_name, None)
        translations = self._parse_translations(raw_value)
        
        if isinstance(value, dict):
            # Setting multiple translations at once
            translations.update(value)
        else:
            # Setting value for current language
            current_lang = get_language() or 'en'
            translations[current_lang] = str(value)
        
        # Store back as JSON
        setattr(instance, self.field_name, json.dumps(translations))
    
    def _parse_translations(self, value):
        """Parse stored translations from various formats."""
        if not value:
            return {}
        
        if isinstance(value, dict):
            return value
        
        if isinstance(value, str):
            try:
                parsed = json.loads(value)
                if isinstance(parsed, dict):
                    return parsed
            except (json.JSONDecodeError, TypeError):
                pass
            
            # If it's a plain string, treat as current language value
            current_lang = get_language() or 'en'
            return {current_lang: value}
        
        return {}


class TranslatableModelMixin:
    """
    Mixin that adds language-specific property access to models.
    
    This allows accessing specific language versions of translatable fields:
    obj.field_name_en, obj.field_name_de, etc.
    """
    
    def __getattr__(self, name):
        # Check if this is a language-specific field access
        if '_' in name:
            field_name, lang_code = name.rsplit('_', 1)
            
            # Check if the base field exists and is translatable
            if hasattr(self._meta.model, field_name):
                field = self._meta.get_field(field_name)
                if hasattr(field, 'translatable') and field.translatable:
                    raw_value = getattr(self, field_name)
                    translations = self._parse_field_translations(raw_value)
                    return translations.get(lang_code, '')
        
        raise AttributeError(f"'{self.__class__.__name__}' object has no attribute '{name}'")
    
    def __setattr__(self, name, value):
        # Check if this is a language-specific field access
        if '_' in name and not name.startswith('_'):
            field_name, lang_code = name.rsplit('_', 1)
            
            # Check if the base field exists and is translatable
            if hasattr(self._meta.model, field_name):
                try:
                    field = self._meta.get_field(field_name)
                    if hasattr(field, 'translatable') and field.translatable:
                        # Get existing translations
                        raw_value = getattr(self, field_name, None)
                        translations = self._parse_field_translations(raw_value)
                        
                        # Update the specific language
                        translations[lang_code] = str(value) if value is not None else ''
                        
                        # Store back as JSON
                        super().__setattr__(field_name, json.dumps(translations))
                        return
                except:
                    # If there's any error, fall back to normal attribute setting
                    pass
        
        super().__setattr__(name, value)
    
    def _parse_field_translations(self, value):
        """Parse stored translations from various formats."""
        if not value:
            return {}
        
        if isinstance(value, dict):
            return value
        
        if isinstance(value, str):
            try:
                parsed = json.loads(value)
                if isinstance(parsed, dict):
                    return parsed
            except (json.JSONDecodeError, TypeError):
                pass
            
            # If it's a plain string, treat as current language value
            current_lang = get_language() or 'en'
            return {current_lang: value}
        
        return {}
    
    def get_translation(self, field_name, language_code):
        """Get translation for a specific field and language."""
        if not hasattr(self, field_name):
            raise AttributeError(f"Field '{field_name}' does not exist")
        
        raw_value = getattr(self, field_name)
        translations = self._parse_field_translations(raw_value)
        return translations.get(language_code, '')
    
    def set_translation(self, field_name, language_code, value):
        """Set translation for a specific field and language."""
        if not hasattr(self, field_name):
            raise AttributeError(f"Field '{field_name}' does not exist")
        
        raw_value = getattr(self, field_name, None)
        translations = self._parse_field_translations(raw_value)
        translations[language_code] = str(value) if value is not None else ''
        setattr(self, field_name, json.dumps(translations))
    
    def get_all_translations(self, field_name):
        """Get all translations for a specific field."""
        if not hasattr(self, field_name):
            raise AttributeError(f"Field '{field_name}' does not exist")
        
        raw_value = getattr(self, field_name)
        return self._parse_field_translations(raw_value)