apps/catalogue/migrations/0002_book_ancestor.py

   1 # -*- coding: utf-8 -*-
   2 from __future__ import unicode_literals
   3
   4 from django.db import models, migrations
   5
   6
   7 def fix_tree_tags(apps, schema_editor):
   8     """Fixes the ancestry cache."""
   9     # TODO: table names
  10     from django.db import connection, transaction
  11     if connection.vendor == 'postgres':
  12         cursor = connection.cursor()
  13         cursor.execute("""
  14             WITH RECURSIVE ancestry AS (
  15                 SELECT book.id, book.parent_id
  16                 FROM catalogue_book AS book
  17                 WHERE book.parent_id IS NOT NULL
  18                 UNION
  19                 SELECT ancestor.id, book.parent_id
  20                 FROM ancestry AS ancestor, catalogue_book AS book
  21                 WHERE ancestor.parent_id = book.id
  22                     AND book.parent_id IS NOT NULL
  23                 )
  24             INSERT INTO catalogue_book_ancestor
  25                 (from_book_id, to_book_id)
  26                 SELECT id, parent_id
  27                 FROM ancestry
  28                 ORDER BY id;
  29             """)
  30     else:
  31         Book = apps.get_model("catalogue", "Book")
  32         for b in Book.objects.exclude(parent=None):
  33             parent = b.parent
  34             while parent is not None:
  35                 b.ancestor.add(parent)
  36                 parent = parent.parent
  37
  38
  39 def remove_book_tags(apps, schema_editor):
  40     Tag = apps.get_model("catalogue", "Tag")
  41     Book = apps.get_model("catalogue", "Book")
  42     Tag.objects.filter(category='book').delete()
  43
  44
  45 class Migration(migrations.Migration):
  46
  47     dependencies = [
  48         ('catalogue', '0001_initial'),
  49     ]
  50
  51     operations = [
  52         migrations.AddField(
  53             model_name='book',
  54             name='ancestor',
  55             field=models.ManyToManyField(related_name=b'descendant', null=True, editable=False, to='catalogue.Book', blank=True),
  56             preserve_default=True,
  57         ),
  58
  59         migrations.RunPython(fix_tree_tags),
  60         migrations.RunPython(remove_book_tags),
  61
  62         migrations.AlterField(
  63             model_name='tag',
  64             name='category',
  65             field=models.CharField(db_index=True, max_length=50, verbose_name='Category', choices=[(b'author', 'author'), (b'epoch', 'period'), (b'kind', 'form'), (b'genre', 'genre'), (b'theme', 'motif'), (b'set', 'set'), (b'thing', 'thing')]),
  66         ),
  67
  68         migrations.RemoveField(
  69             model_name='tag',
  70             name='book_count',
  71         ),
  72         migrations.RemoveField(
  73             model_name='tag',
  74             name='picture_count',
  75         ),
  76         migrations.RemoveField(
  77             model_name='book',
  78             name='_related_info',
  79         ),
  80     ]