✨(backend) add creator field on document and allow filtering on it

We want to be able to limit the documents displayed on a logged-in user's
list view by the documents they created or by the documents that other
users created.

This is different from having the "owner" role on a document because this
can be acquired and even lost. What we want here is to be able to
identify documents by the user who created them so we add a new field.

src/backend/core/migrations/0010_add_field_creator_to_document.py

@@ -0,0 +1,31 @@
+# Generated by Django 5.1.2 on 2024-11-09 11:36
+
+import django.core.validators
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0009_add_document_favorite'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='document',
+            name='creator',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.RESTRICT, related_name='documents_created', to=settings.AUTH_USER_MODEL),
+        ),
+        migrations.AlterField(
+            model_name='user',
+            name='language',
+            field=models.CharField(choices="(('en-us', 'English'), ('fr-fr', 'French'), ('de-de', 'German'))", default='en-us', help_text='The language in which the user wants to see the interface.', max_length=10, verbose_name='language'),
+        ),
+        migrations.AlterField(
+            model_name='user',
+            name='sub',
+            field=models.CharField(blank=True, help_text='Required. 255 characters or fewer. Letters, numbers, and @/./+/-/_/: characters only.', max_length=255, null=True, unique=True, validators=[django.core.validators.RegexValidator(message='Enter a valid sub. This value may contain only letters, numbers, and @/./+/-/_/: characters.', regex='^[\\w.@+-:]+\\Z')], verbose_name='sub'),
+        ),
+    ]

src/backend/core/migrations/0011_populate_creator_field_and_make_it_required.py

@@ -0,0 +1,52 @@
+# Generated by Django 5.1.2 on 2024-11-09 11:48
+
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations
+from django.db.models import F, ForeignKey, Subquery, OuterRef, Q
+
+
+def set_creator_from_document_access(apps, schema_editor):
+    """
+    Populate the `creator` field for existing Document records.
+
+    This function assigns the `creator` field using the existing
+    DocumentAccess entries. We can be sure that all documents have at
+    least one user with "owner" role. If the document has several roles,
+    it should take the entry with the oldest date of creation.
+
+    The update is performed using efficient bulk queries with Django's
+    Subquery and OuterRef to minimize database hits and ensure performance.
+
+    Note: After running this migration, we quickly modify the schema to make
+    the `creator` field required.
+    """
+    Document = apps.get_model("core", "Document")
+    DocumentAccess = apps.get_model("core", "DocumentAccess")
+
+    # Update `creator` using the "owner" role
+    owner_subquery = DocumentAccess.objects.filter(
+        document=OuterRef('pk'),
+        user__isnull=False,
+        role='owner',
+    ).order_by('created_at').values('user_id')[:1]
+
+    Document.objects.filter(
+        creator__isnull=True
+    ).update(creator=Subquery(owner_subquery))
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0010_add_field_creator_to_document'),
+    ]
+
+    operations = [
+        migrations.RunPython(set_creator_from_document_access, reverse_code=migrations.RunPython.noop),
+        migrations.AlterField(
+            model_name='document',
+            name='creator',
+            field=ForeignKey(on_delete=django.db.models.deletion.RESTRICT, related_name='documents_created', to=settings.AUTH_USER_MODEL),
+        ),
+    ]