Features: 1) Add translate_fields management command for field translations via DeepL; 2) Add slug population script in 0022_category_slug migration.

Fixes: 1) Update locale codes in `deepl_translate.py` to lowercase for consistency.

Extra: 1) Minor refactoring to ensure compatibility and avoid undefined behavior in slug population logic.

core/management/commands/deepl_translate.py

@@ -9,23 +9,23 @@ from django.core.management.base import BaseCommand, CommandError
 
 # Mapping from Django locale codes to DeepL API codes
 DEEPL_TARGET_LANGUAGES_MAPPING = {
-    "en-GB": "EN-GB",
-    "ar-AR": "AR",
-    "cs-CZ": "CS",
-    "da-DK": "DA",
-    "de-DE": "DE",
-    "en-US": "EN-US",
-    "es-ES": "ES",
-    "fr-FR": "FR",
-    "hi-IN": "unsupported",
-    "it-IT": "IT",
-    "ja-JP": "JA",
-    "kk-KZ": "unsupported",
-    "nl-NL": "NL",
-    "pl-PL": "PL",
-    "pt-BR": "PT-BR",
-    "ro-RO": "RO",
-    "ru-RU": "RU",
+    "en-gb": "EN-GB",
+    "ar-ar": "AR",
+    "cs-cz": "CS",
+    "da-dk": "DA",
+    "de-de": "DE",
+    "en-us": "EN-US",
+    "es-es": "ES",
+    "fr-fr": "FR",
+    "hi-in": "unsupported",
+    "it-it": "IT",
+    "ja-jp": "JA",
+    "kk-kz": "unsupported",
+    "nl-nl": "NL",
+    "pl-pl": "PL",
+    "pt-br": "PT-BR",
+    "ro-ro": "RO",
+    "ru-ru": "RU",
     "zh-hans": "ZH-HANS",
 }
 

core/management/commands/translate_fields.py

@@ -0,0 +1,137 @@
+import importlib
+import os
+
+import requests
+from django.core.management.base import BaseCommand, CommandError
+from django.db import transaction
+
+DEEPL_API_URL = "https://api-free.deepl.com/v2/translate"
+
+DEEPL_TARGET_LANGUAGES_MAPPING = {
+    "en-gb": "EN-GB",
+    "ar-ar": "AR",
+    "cs-cz": "CS",
+    "da-dk": "DA",
+    "de-de": "DE",
+    "en-us": "EN-US",
+    "es-es": "ES",
+    "fr-fr": "FR",
+    "hi-in": "unsupported",
+    "it-it": "IT",
+    "ja-jp": "JA",
+    "kk-kz": "unsupported",
+    "nl-nl": "NL",
+    "pl-pl": "PL",
+    "pt-br": "PT-BR",
+    "ro-ro": "RO",
+    "ru-ru": "RU",
+    "zh-hans": "ZH-HANS",
+}
+
+
+class Command(BaseCommand):
+    help = (
+        "Translate a model field into another language via DeepL and store it "
+        "in the translated_<lang> field created by django-modeltranslation."
+    )
+
+    def add_arguments(self, parser):
+        parser.add_argument(
+            "-t", "--target", required=True,
+            help=(
+                "Dotted path to the field to translate, "
+                "e.g. core.models.Product.description"
+            ),
+        )
+        parser.add_argument(
+            "-l", "--language", required=True,
+            help=(
+                "Modeltranslation language code to translate into, "
+                "e.g. de-de, fr-fr, zh-hans"
+            ),
+        )
+
+    def handle(self, *args, **options):
+        target = options["target"]
+        lang = options["language"].lower()
+
+        if lang not in DEEPL_TARGET_LANGUAGES_MAPPING:
+            raise CommandError(f"Unknown language '{lang}'.")
+        deepl_lang = DEEPL_TARGET_LANGUAGES_MAPPING[lang]
+        if deepl_lang == "unsupported":
+            raise CommandError(f"DeepL does not support translating into '{lang}'.")
+
+        try:
+            module_path, model_name, field_name = target.rsplit(".", 2)
+        except ValueError:
+            raise CommandError(
+                "Invalid target format. Use app.module.Model.field, e.g. core.models.Product.description"
+            )
+
+        try:
+            module = importlib.import_module(module_path)
+            model = getattr(module, model_name)
+        except (ImportError, AttributeError) as e:
+            raise CommandError(f"Could not import model '{model_name}' from '{module_path}': {e}")
+
+        dest_suffix = lang.replace("-", "_")
+        dest_field = f"{field_name}_{dest_suffix}"
+
+        if not hasattr(model, dest_field):
+            raise CommandError(
+                f"Model '{model_name}' has no field '{dest_field}'. "
+                "Did you run makemigrations/migrate after setting up modeltranslation?"
+            )
+
+        auth_key = os.environ.get("DEEPL_AUTH_KEY")
+        if not auth_key:
+            raise CommandError("Environment variable DEEPL_AUTH_KEY is not set.")
+
+        qs = model.objects.exclude(**{f"{field_name}__isnull": True}) \
+            .exclude(**{f"{field_name}": ""})
+        total = qs.count()
+        if total == 0:
+            self.stdout.write("No instances with non-empty source field found.")
+            return
+
+        self.stdout.write(f"Translating {total} objects from '{field_name}' into '{dest_field}'.")
+
+        for obj in qs.iterator():
+            src_text = getattr(obj, field_name)
+            existing = getattr(obj, dest_field, None)
+            if existing:
+                self.stdout.write(f"Skipping {obj.pk}: '{dest_field}' already set.")
+                continue
+
+            resp = requests.post(
+                DEEPL_API_URL,
+                data={
+                    "auth_key": auth_key,
+                    "text": src_text,
+                    "target_lang": deepl_lang,
+                },
+                timeout=30,
+            )
+            if resp.status_code != 200:
+                self.stderr.write(
+                    f"DeepL API error for {obj.pk}: {resp.status_code} {resp.text}"
+                )
+                continue
+
+            data = resp.json()
+            try:
+                translated = data["translations"][0]["text"]
+            except (KeyError, IndexError):
+                self.stderr.write(f"Unexpected DeepL response for {obj.pk}: {data}")
+                continue
+
+            setattr(obj, dest_field, translated)
+            try:
+                with transaction.atomic():
+                    obj.save(update_fields=[dest_field])
+            except Exception as e:
+                self.stderr.write(f"Error saving {obj.pk}: {e}")
+            else:
+                self.stdout.write(f"✓ {obj.pk}")
+
+        self.stdout.write(self.style.SUCCESS("Done."))

core/migrations/0022_category_slug.py

@@ -4,12 +4,20 @@ import django_extensions.db.fields
 from django.db import migrations
 
 
+def populate_slugs(apps, schema_editor):
+    Category = apps.get_model('core', 'Category')
+    for category in Category.objects.all():
+        if not category.slug:
+            category.save()
+
+
 class Migration(migrations.Migration):
     dependencies = [
         ('core', '0021_rename_name_ar_ar_attribute_name_ar_ar_and_more'),
     ]
 
     operations = [
+        migrations.RunPython(populate_slugs, reverse_code=migrations.RunPython.noop),
         migrations.AddField(
             model_name='category',
             name='slug',