Switches FileDistribution use Distribution

pulpcore==3.12 introduces a new MasterModel named `Distribution`
designed to replace the `BaseDistribution` MasterModel. This PR switches
the `FileDistribution` to use `Distribution`. It also ships a migration
which moves the data from the `BaseDistribution` table to the
`Distribution` field.

Required PR: pulp/pulpcore#1198

closes #8387

CHANGES/8387.misc

@@ -0,0 +1,2 @@
+Switches ``FileDistribution`` to inherit from ``Distribution`` instead of ``BaseDistribution``.
+Additionally ship a migration which moves the data from ``BaseDistribution`` to ``Distribution``.

pulp_file/app/migrations/0009_move_data_to_new_master_distribution_model.py

@@ -0,0 +1,76 @@
+# Generated by Django 2.2.19 on 2021-03-19 17:42
+
+from django.db import connection, migrations, models, transaction
+import django.db.models.deletion
+
+
+pks_to_delete = []
+
+
+def migrate_data_from_old_master_model_to_new_master_model(apps, schema_editor):
+    FileDistribution = apps.get_model('file', 'FileDistribution')
+    CoreDistribution = apps.get_model('core', 'Distribution')
+    for old_file_distribution in FileDistribution.objects.all():
+        with transaction.atomic():
+            new_master_model_entry = CoreDistribution(
+                pulp_id=old_file_distribution.pulp_id,
+                pulp_created=old_file_distribution.pulp_created,
+                pulp_last_updated=old_file_distribution.pulp_last_updated,
+                pulp_type=old_file_distribution.pulp_type,
+                name=old_file_distribution.name,
+                base_path=old_file_distribution.base_path,
+                content_guard=old_file_distribution.content_guard,
+                remote=old_file_distribution.remote,
+                publication=old_file_distribution.publication,
+            )
+            new_master_model_entry.save()
+            old_file_distribution.distribution_ptr = new_master_model_entry
+            old_file_distribution.save()
+            pks_to_delete.append(old_file_distribution.pulp_id)
+
+
+def delete_remaining_old_master_model_entries(apps, schema_editor):
+    with connection.cursor() as cursor:
+        for pk in pks_to_delete:
+            cursor.execute("DELETE from core_basedistribution WHERE pulp_id = %s", [pk])
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0062_add_new_distribution_mastermodel'),
+        ('file', '0008_add_manifest_field'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='filedistribution',
+            name='distribution_ptr',
+            field=models.OneToOneField(auto_created=True, null=True, default=None,
+                                       on_delete=django.db.models.deletion.CASCADE,
+                                       parent_link=True, primary_key=False,
+                                       related_name='file_filedistribution', serialize=False,
+                                       to='core.Distribution'),
+            preserve_default=False,
+        ),
+        migrations.RunPython(migrate_data_from_old_master_model_to_new_master_model),
+        migrations.RemoveField(
+            model_name='filedistribution',
+            name='basedistribution_ptr',
+        ),
+        migrations.AlterField(
+            model_name='filedistribution',
+            name='distribution_ptr',
+            field=models.OneToOneField(auto_created=True,
+                                       on_delete=django.db.models.deletion.CASCADE,
+                                       parent_link=True, primary_key=True,
+                                       related_name='file_filedistribution', serialize=False,
+                                       to='core.Distribution'),
+            preserve_default=False,
+        ),
+        migrations.RemoveField(
+            model_name='filedistribution',
+            name='publication',
+        ),
+        migrations.RunPython(delete_remaining_old_master_model_entries),
+    ]

pulp_file/app/models.py

@@ -4,9 +4,9 @@
 
 from pulpcore.plugin.models import (
     Content,
+    Distribution,
     FilesystemExporter,
     Publication,
-    PublicationDistribution,
     Remote,
     Repository,
 )
@@ -98,7 +98,7 @@ def finalize_new_publication(self):
         validate_publication_paths(self)
 
 
-class FileDistribution(PublicationDistribution):
+class FileDistribution(Distribution):
     """
     Distribution for 'file' content.
     """

pulp_file/app/serializers.py

@@ -6,8 +6,8 @@
 from pulpcore.plugin.serializers import (
     ContentChecksumSerializer,
     DetailRelatedField,
+    DistributionSerializer,
     FilesystemExporterSerializer,
-    PublicationDistributionSerializer,
     PublicationSerializer,
     RemoteSerializer,
     RepositorySerializer,
@@ -91,7 +91,7 @@ class FilePublicationSerializer(PublicationSerializer):
 
     distributions = DetailRelatedField(
         help_text=_("This publication is currently hosted as defined by these distributions."),
-        source="file_filedistribution",
+        source="distribution_set",
         view_name="filedistributions-detail",
         many=True,
         read_only=True,
@@ -106,13 +106,21 @@ class Meta:
         fields = PublicationSerializer.Meta.fields + ("distributions", "manifest")
 
 
-class FileDistributionSerializer(PublicationDistributionSerializer):
+class FileDistributionSerializer(DistributionSerializer):
     """
     Serializer for File Distributions.
     """
 
+    publication = DetailRelatedField(
+        required=False,
+        help_text=_("Publication to be served"),
+        view_name_pattern=r"publications(-.*/.*)?-detail",
+        queryset=models.Publication.objects.exclude(complete=False),
+        allow_null=True,
+    )
+
     class Meta:
-        fields = PublicationDistributionSerializer.Meta.fields
+        fields = DistributionSerializer.Meta.fields + ("publication",)
         model = FileDistribution
 
 

pulp_file/app/viewsets.py

@@ -11,8 +11,8 @@
 )
 from pulpcore.plugin.tasking import enqueue_with_reservation, fs_publication_export
 from pulpcore.plugin.viewsets import (
-    BaseDistributionViewSet,
     ContentFilter,
+    DistributionViewSet,
     ExporterViewSet,
     ExportViewSet,
     OperationPostponedResponse,
@@ -166,7 +166,7 @@ def create(self, request):
         return OperationPostponedResponse(result, request)
 
 
-class FileDistributionViewSet(BaseDistributionViewSet):
+class FileDistributionViewSet(DistributionViewSet):
     """
     <!-- User-facing documentation, rendered as html-->
     FileDistributions host <a href="#operation/publications_file_file_list">File