moviewyrm/bookwyrm/migrations/0046_reviewrating.py

# Generated by Django 3.0.7 on 2021-02-25 18:36

from django.db import migrations, models
from django.db import connection
from django.db.models import Q
import django.db.models.deletion
from psycopg2.extras import execute_values

def convert_review_rating(app_registry, schema_editor):
    ''' take rating type Reviews and convert them to ReviewRatings '''
    db_alias = schema_editor.connection.alias

    reviews = app_registry.get_model(
        'bookwyrm', 'Review'
    ).objects.using(db_alias).filter(
        Q(content__isnull=True) | Q(content='')
    )

    with connection.cursor() as cursor:
        values = [(r.id,) for r in reviews]
        execute_values(cursor, '''
INSERT INTO bookwyrm_reviewrating(review_ptr_id)
VALUES %s''', values)

def unconvert_review_rating(app_registry, schema_editor):
    ''' undo the conversion from ratings back to reviews'''
    # All we need to do to revert this is drop the table, which Django will do
    # on its own, as long as we have a valid reverse function. So, this is a
    # no-op function so Django will do its thing

class Migration(migrations.Migration):

    dependencies = [
        ('bookwyrm', '0045_auto_20210210_2114'),
    ]

    operations = [
        migrations.CreateModel(
            name='ReviewRating',
            fields=[
                ('review_ptr', models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='bookwyrm.Review')),
            ],
            options={
                'abstract': False,
            },
            bases=('bookwyrm.review',),
        ),
        migrations.RunPython(convert_review_rating, unconvert_review_rating),
    ]