make translations cache-happy

apps/amo/__init__.py

@@ -5,6 +5,7 @@ import functools
 
 from django.core import paginator
 
+from .managers import CachingManager
 from .models import LegacyModel, TranslatedField
 
 

apps/amo/models.py

@@ -1,5 +1,7 @@
 from django.db import models
 
+from . import managers
+
 
 class LegacyModel(models.Model):
     """Adds automatic created and modified fields to the model."""
@@ -15,9 +17,11 @@ class TranslatedField(models.IntegerField):
 
     def to_python(self, value):
         locale = 'en-US'
-        q = Translation.objects.filter(id=value, locale=locale)
-        v = q.values_list('localized_string', flat=True)
-        return v[0] if v else value
+        try:
+            o = Translation.objects.get(id=value, locale=locale)
+            return o.localized_string
+        except Translation.DoesNotExist:
+            return value
 
 
 # Putting Translation in here since TranslatedField depends on it.
@@ -28,5 +32,11 @@ class Translation(LegacyModel):
     locale = models.CharField(max_length=10)
     localized_string = models.TextField()
 
+    objects = managers.CachingManager()
+
     class Meta:
         db_table = 'translations'
+
+    @property
+    def cache_key(self):
+        return self._cache_key(id=self.id, locale=self.locale)