Django modeltranslation slug problem. When i change language dont go right url

Question

modeltranslation...

i change title, content and slug sections on my translation.py. Everything work is fine but i have a problem.

let me try to explain;

i have one post in my website and this post "slug" like this;

slug_en = some_en_slug

slug_fr = some_fr_slug

And i have one language changer on my navbar.

     {% get_current_language as LANGUAGE_CODE %}
     {% get_available_languages as LANGUAGES %}
     {% get_language_info_list for LANGUAGES as languages %}

<form action="{% url "set_language" %}" method="post" class="navbar-form navbar-right">
{% csrf_token %}
<div class="form-group">
    <select name="language" class="form-control" onchange="this.form.submit()">
    {% for language in languages %}
    <option value="{{ language.code }}"
        {% if language.code == LANGUAGE_CODE %}selected="selected"{% endif %}>
        {{ language.name_local }}
    </option>
    {% endfor %}
    </select>
</div>
</form>

Actually this lang. changer working fine. This is change all slug href url's on outside post... But this didnt change slug url in post page.

when i go this url;

https://example.com/en/en_slug

and after try change language, my browser is going this url;

https://example.com/fr/en_slug and i see 404 page..

i need to go to https://example.com/fr/fr_slug this url after change language ...

I dont have any idea for this. I would like your help.

urls.py
from django.urls import path
from . import views
from django.utils.translation import gettext_lazy as _

app_name = "article"


urlpatterns = [
    path(_('dashboard/'),views.dashboard,name="dashboard"),
    path(_('addarticle/'),views.addarticle,name="addarticle"),
    path('<slug>',views.detail,name="detail"),
    path('edit/<int:id>',views.editArticle,name="edit"),
    path('delete/<int:id>',views.deleteArticle,name="delete"),
    path(_('article/'),views.articles,name="article"),
    path('comment/<int:id>',views.addcomment,name="comment"),
    path('category/<slug>', views.category_detail,name="category_detail" )
]

models.py

from django.db import models
from ckeditor.fields import RichTextField
from django.utils.text import slugify

class Article(models.Model):

    author = models.ForeignKey("auth.User",on_delete = models.CASCADE, verbose_name="Author")
    title = models.CharField(max_length = 120, verbose_name="Title")
    category = models.ForeignKey('Category', on_delete = models.CASCADE, null=True, blank=True)
    content = RichTextField(verbose_name="Content")
    created_date = models.DateTimeField(auto_now_add=True, verbose_name="Created Date")
    image = models.ImageField(blank=True, null=True, verbose_name="Add Image (.jpg .png)")
    slug = models.SlugField(unique=True, max_length = 130)

    def __str__(self):
        return self.title

    def get_unique_slug(self):
        slug = slugify(self.title.replace("ı","i"))
        unique_slug = slug
        counter = 1
        while Article.objects.filter(slug=unique_slug).exists():
            unique_slug = '{}-{}'.format(slug, counter)
            counter += 1
        return unique_slug

    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug = self.get_unique_slug()
        return super(Article, self).save(*args, **kwargs)

translation.py

from modeltranslation.translator import translator, TranslationOptions
from .models import Article

class ArticleTranslationOptions(TranslationOptions):
    fields = ('title', 'content','slug')

translator.register(Article, ArticleTranslationOptions)

view.py

from django.shortcuts import render,  get_object_or_404
from .models import Article, Category
from django.core.paginator import Paginator
from django.utils.translation import gettext as _

def index(request): 
    from django.utils import translation  
    articles = Article.objects.all()
    category = Category.objects.all()

    context = {
        "articles": articles,
        "category": category,

         }

    return render(request, 'index.html', context)

def detail(request,slug):
    article = get_object_or_404(Article, slug = slug)
    category = Category.objects.all()

    return render(request, "detail.html", {"article":article, "category":category,})



def category_detail(request,slug):
    template = "category_detail.html"

    category=get_object_or_404(Category,slug=slug)
    article=Article.objects.filter(category=category)

    context = {
        'category' : category,
        'article' : article,
    }
    return render(request,template,context)

def category_page(request):
    object_list = Category.objects.all()
    context = {'object_list': object_list,}
    return render(request, 'detail.html', context)

I think i need some changes in urls.py but i dont know :/

Thanks for help...

Answer 1

In your detail view you should try matching the slug for all the languages:

from django.conf import settings
from django.db.models import Q

languages = dict(settings.LANGUAGES).keys()
q = Q()
for lang in languages:
    kwargs = {'slug_%s' % lang: slug}
    q |= Q(**kwargs)
articles = Article.objects.filter(q)
if articles.exists():
    article = articles.first()
else:
    return Http404

If you want to switch the URL to the correct slug for the current language, you could add the following line after article = articles.first():

if not article.slug == slug:  
    # slug is a different language than the current one
    return redirect(reverse("detail", kwargs={'slug': article.slug}))

Note that this will add a round-trip and refetch the same article a second time, but I don't see how you would otherwise change the URL.