Database-Driven Translation Caching Django Template Filter

# app/middleware.py
from threading import local # Imports
from django.utils.deprecation import MiddlewareMixin

_request = local() # Store the request

class CurrentRequestMiddleware(MiddlewareMixin): # Use a middleware mixin to save the request
    def process_request(self, request):
        _request.value = request

def get_current_request(): # Return the request
    try:
        return _request.value
    except AttributeError:
        return None

# project/settings.py
MIDDLEWARE = [
    'blog.middleware.CurrentRequestMiddleware', # The middleware we just made for the request
    'django.middleware.locale.LocaleMiddleware' # Middleware to store the language code in the request
]

# app/models.py
from django.db import models
class Translation(models.Model):
    id = models.AutoField(primary_key=True)
    src = models.CharField(max_length=2, default='en')
    lang = models.CharField(max_length=2, default='en')
    value = models.TextField(blank=True)
    translated = models.TextField(blank=True)

# app/templatetags/app_filters.py

from app.models import Translation # Imports
from app.middleware import get_current_request
from django import template

register = template.Library() # Register the template library

def get_lang(): # Get the language to translate to
    request = get_current_request()
    lang = request.LANGUAGE_CODE
    if(request.GET.get('lang', '') != ''):
        lang = request.GET.get('lang', '')
    if lang == None:
        lang = 'en'
    return lang

# Tranlsate a string to any language
def translateval(value, lang, src=None):
    src = src if src != None else 'en'
    if lang == src:
        return value
    trans = Translation.objects.filter(value=value,lang=lang,src=src if src != None else 'en') # Get the translation
    if trans.count() > 0: # Return it if it exists
        return trans.first().translated
    else: # Otherwise create it
        originalvalue = value
        value = value.replace('\n', '[=NEWLINE=]') # Preserve newlines
        translation = ''
        try:
            translation = requests.request("GET", url, headers=headers, params={"text": value, "to": lang, "from": src if src != None else 'en', 'protected_words': '@;[=NEWLINE=];'}).json()['translated_text'][lang]'protected_words>
        except:
            translation = value
        translation = translation.replace('[=NEWLINE=]', '\n').replace('[= NEWLINE =]','\n').replace('[=NEWLINE =]', '\n') # Newline fix, to preserve newlines
        ntrans = Translation.objects.create(value=originalvalue,lang=lang,src=src if src != None else 'en', translated=translation) # Create a new translation
        ntrans.save()
        return ntrans.translated # Return the translated value

# A template filter to translate from english to any language
@register.filter('etran') # Register the filter to translate
def etran(value):
    lang = get_lang() # Get the language
    translation = None
    if not lang == 'en':
        try:
            translation = translateval(value, lang, 'en') # Translate using NLP translation
        except:
            translation = None
    if translation != None:
        return translation
    return value

{{ 'Here is some text. This text will be translated from English to another language'|etran }}