series: Remove the version and n_patches fields from series

Now that we have migrated this information from Series to
SeriesRevision, it's time to remove the fields on Series. We still
provide a revision migration step we can backward if something goes
wrong.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>

patchwork/migrations/0015_remove_version_n_patches.py

@@ -0,0 +1,51 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+def noop(apps, schema_editor):
+    pass
+
+
+def update_version_n_patches(apps, schema_editor):
+    Series = apps.get_model("patchwork", "Series")
+    SeriesRevision = apps.get_model("patchwork", "SeriesRevision")
+
+    query =  Series.objects.all()
+    for _, series in enumerate(query.iterator()):
+        revisions = SeriesRevision.objects.filter(series=series). \
+                    order_by('version').reverse()
+        last_revision = revisions[0]
+
+        for field in series._meta.local_fields:
+            if field.name == "last_updated":
+                field.auto_now = False
+
+        series.version = last_revision.version
+        series.n_patches = last_revision.n_patches
+        series.save()
+
+        for field in series._meta.local_fields:
+            if field.name == "last_updated":
+                field.auto_now = True
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('patchwork', '0014_last_revision'),
+    ]
+
+    operations = [
+        migrations.RunPython(noop, update_version_n_patches),
+
+        migrations.RemoveField(
+            model_name='series',
+            name='n_patches',
+        ),
+        migrations.RemoveField(
+            model_name='series',
+            name='version',
+        ),
+    ]

patchwork/models.py

@@ -470,11 +470,6 @@ class Series(models.Model):
                                  blank=True)
     submitted = models.DateTimeField(default=datetime.datetime.now)
     last_updated = models.DateTimeField(auto_now=True)
-    # Caches the latest version so we can display it without looking at the max
-    # of all SeriesRevision.version
-    version = models.IntegerField(default=1)
-    # This is the number of patches of the latest version.
-    n_patches = models.IntegerField(default=0)
     # direct access to the latest revision so we can get the latest revision
     # information with a JOIN
     last_revision = models.OneToOneField('SeriesRevision', null=True,