Translation cache – v1.0

Author: szabozoltan69

lang/migrations/0007_translationcache.py

@@ -0,0 +1,30 @@
+# Generated by Django 4.2.19 on 2025-07-29 15:43
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("lang", "0006_alter_string_unique_together"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="TranslationCache",
+            fields=[
+                ("id", models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("text", models.TextField()),
+                ("source_language", models.CharField(max_length=16)),
+                ("dest_language", models.CharField(max_length=16)),
+                ("translated_text", models.TextField()),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+            ],
+            options={
+                "indexes": [
+                    models.Index(fields=["text", "source_language", "dest_language"], name="lang_transl_text_4a497b_idx")
+                ],
+                "unique_together": {("text", "source_language", "dest_language")},
+            },
+        ),
+    ]

lang/models.py

@@ -33,3 +33,20 @@ def get_user_permissions_per_language(cls, user):
         return {
             lang_code: user.has_perm(cls._get_permission_per_language_codename(lang_code)) for lang_code, _ in settings.LANGUAGES
         }
+
+
+class TranslationCache(models.Model):
+    text = models.TextField()
+    source_language = models.CharField(max_length=16)
+    dest_language = models.CharField(max_length=16)
+    translated_text = models.TextField()
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        unique_together = ("text", "source_language", "dest_language")
+        indexes = [
+            models.Index(fields=["text", "source_language", "dest_language"]),
+        ]
+
+    def __str__(self):
+        return f"{self.source_language}>{self.dest_language}: {self.text[:30]}..."

lang/tests.py

@@ -1,6 +1,7 @@
 import unittest
 from unittest import mock
 
+import pytest
 from django.conf import settings
 from django.contrib.auth.models import Permission
 from django.core import management
@@ -227,6 +228,7 @@ def test_lang_api_permissions(self):
 
 class TranslatorMockTest(unittest.TestCase):
 
+    @pytest.mark.django_db
     @mock.patch("lang.translation.requests")
     def test_ifrc_translator(self, requests_mock):
         # Simple mock test where we define what the expected response is from provider

lang/translation.py

@@ -7,6 +7,8 @@
 from django.conf import settings
 from django.utils.module_loading import import_string
 
+from .models import TranslationCache
+
 logger = logging.getLogger(__name__)
 
 
@@ -133,7 +135,21 @@ def translate_text(self, text, dest_language, source_language=None):
             # NOTE: Sending 'text' throws 500 from IFRC translation endpoint
             # So only sending if html
             payload["textType"] = "html"
-        logger.info(f"IFRC translation API call content: {text[:30]}... to {dest_language} from {source_language}")
+
+        # Try cache at first (for shorter texts)
+        use_cache = len(text) < 200
+
+        if use_cache:
+            cache = TranslationCache.objects.filter(
+                text=text,
+                source_language=source_language or "",  # source_language can be "detected"
+                dest_language=dest_language,
+            ).first()
+            if cache:
+                logger.info(f"translation cache hit: {text[:30]}... {source_language}>{dest_language}")
+                return cache.translated_text
+
+        logger.info(f"IFRC translation API call: {text[:30]}... {source_language}>{dest_language}")
         response = requests.post(
             self.url,
             headers=self.headers,
@@ -142,7 +158,17 @@ def translate_text(self, text, dest_language, source_language=None):
 
         # Not using == 200 – it would break tests with MagicMock name=requests.post() results
         if response.status_code != 500:
-            return response.json()[0]["translations"][0]["text"] + textTail
+            translated = response.json()[0]["translations"][0]["text"]
+
+            # Cache the translation if original text was short enough
+            if use_cache:
+                TranslationCache.objects.create(
+                    text=text,
+                    source_language=source_language or "",  # source_language can be "detected"
+                    dest_language=dest_language,
+                    translated_text=translated,
+                )
+            return translated + textTail
 
 
 def get_translator_class():