bookwyrm/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),
    ]