fix: remove null=True from UserOrigin.origin_id

Possibly a race condition in authentication created duplicate
UserOrigin instances for a user with the same data source.
Since origin_id was null by default, it didn't hit the
data_source & origin_id uniqueness constraint. Null
is not handled the same way as an empty string in postgres.

With an empty string as the default the duplicate issue, which
required manual work to fix, shouldn't happen anymore.

Refs: HAUKI-656

users/migrations/0004_alter_userorigin_origin_id.py

@@ -0,0 +1,21 @@
+# Generated by Django 4.2.13 on 2024-07-25 09:41
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("users", "0003_userorigin"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="userorigin",
+            name="origin_id",
+            field=models.CharField(
+                blank=True, default="", max_length=100, verbose_name="Origin ID"
+            ),
+            preserve_default=False,
+        ),
+    ]

users/models.py

@@ -35,7 +35,7 @@ class UserOrigin(models.Model):
     user = models.ForeignKey(User, related_name="origins", on_delete=models.CASCADE)
     data_source = models.ForeignKey("hours.DataSource", on_delete=models.CASCADE)
     origin_id = models.CharField(
-        verbose_name=_("Origin ID"), max_length=100, null=True, blank=True
+        verbose_name=_("Origin ID"), max_length=100, blank=True
     )
 
     class Meta:

users/tests/conftest.py

@@ -0,0 +1,6 @@
+from pytest_factoryboy import register
+
+from hours.tests.conftest import DataSourceFactory, UserFactory
+
+register(UserFactory)
+register(DataSourceFactory)

users/tests/test_models.py

@@ -0,0 +1,14 @@
+import pytest
+from django.db import IntegrityError
+
+from users.models import UserOrigin
+
+
+@pytest.mark.django_db
+def test_user_origin_shouldnt_allow_duplicate_empty_origin_id(user, data_source):
+    """Duplicate UserOrigin instances shouldn't get created when data source is
+    the same but origin_id is empty.
+    """
+    UserOrigin.objects.create(user=user, data_source=data_source)
+    with pytest.raises(IntegrityError):
+        UserOrigin.objects.create(user=user, data_source=data_source)