fix: adds unique_together

and fixes nit

openedx_tagging/core/tagging/migrations/0004_auto_20230723_2001.py

@@ -0,0 +1,35 @@
+# Generated by Django 3.2.19 on 2023-07-24 01:01
+
+from django.db import migrations, models
+import openedx_learning.lib.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('oel_tagging', '0003_auto_20230721_1238'),
+    ]
+
+    operations = [
+        migrations.RemoveIndex(
+            model_name='tag',
+            name='oel_tagging_taxonom_89e779_idx',
+        ),
+        migrations.RemoveIndex(
+            model_name='tag',
+            name='oel_tagging_taxonom_44e355_idx',
+        ),
+        migrations.AlterField(
+            model_name='objecttag',
+            name='object_id',
+            field=openedx_learning.lib.fields.MultiCollationCharField(db_collations={'mysql': 'utf8mb4_unicode_ci', 'sqlite': 'NOCASE'}, db_index=True, editable=False, help_text='Identifier for the object being tagged', max_length=255),
+        ),
+        migrations.AlterUniqueTogether(
+            name='tag',
+            unique_together={('taxonomy', 'value'), ('taxonomy', 'external_id')},
+        ),
+        migrations.AddIndex(
+            model_name='objecttag',
+            index=models.Index(fields=['taxonomy', 'object_id'], name='oel_tagging_taxonom_aa24e6_idx'),
+        ),
+    ]

openedx_tagging/core/tagging/models/base.py

@@ -62,9 +62,9 @@ class Tag(models.Model):
     )
 
     class Meta:
-        indexes = [
-            models.Index(fields=["taxonomy", "value"]),
-            models.Index(fields=["taxonomy", "external_id"]),
+        unique_together = [
+            ["taxonomy", "external_id"],
+            ["taxonomy", "value"],
         ]
 
     def __repr__(self):
@@ -443,6 +443,7 @@ class ObjectTag(models.Model):
     id = models.BigAutoField(primary_key=True)
     object_id = case_insensitive_char_field(
         max_length=255,
+        db_index=True,
         editable=False,
         help_text=_("Identifier for the object being tagged"),
     )
@@ -484,6 +485,7 @@ class ObjectTag(models.Model):
 
     class Meta:
         indexes = [
+            models.Index(fields=["taxonomy", "object_id"]),
             models.Index(fields=["taxonomy", "_value"]),
         ]
 
@@ -556,7 +558,6 @@ def tag_ref(self, tag_ref: str):
             try:
                 self.tag = self.taxonomy.tag_set.get(pk=tag_ref)
                 self.value = self.tag.value
-                return
             except (ValueError, Tag.DoesNotExist):
                 # This might be ok, e.g. if our taxonomy.allow_free_text, so we just pass through here.
                 # We rely on the caller to validate before saving.