Extra 4.0 release notes

[meshy]

We ran into some issues when upgrading from version 3. This updates the release notes to help clarify the process.

You may be interested in the migration we wrote (in another app) to get this going:

from __future__ import unicode_literals

from django.db import migrations

EXISTS_SQL = """
    SELECT EXISTS (
        SELECT 1
        FROM pg_tables
        WHERE tablename = '{old}'
    );
"""

DROP_TABLE_SQL = 'DROP TABLE {new};'
RENAME_SQL = 'ALTER TABLE {old} RENAME TO {new};'

def forward(apps, schema_editor):
    with schema_editor.connection.cursor() as cursor:
        tables = (
            'notifications_noticequeuebatch',
            'notifications_noticesetting',
            'notifications_noticetype',
        )
        for old_table in tables:
            new_table = 'pinax_' + old_table

            cursor.execute(EXISTS_SQL.format(old=old_table))

            (old_table_exists,) = cursor.fetchone()
            if old_table_exists:
                cursor.execute(DROP_TABLE_SQL.format(new=new_table))
                cursor.execute(RENAME_SQL.format(old=old_table, new=new_table))

class Migration(migrations.Migration):

    dependencies = [('pinax_notifications', '0001_initial')]
    run_before = [('pinax_notifications', '0002_auto_20171003_2006')]

    operations = [migrations.RunPython(forward, migrations.RunPython.noop)]

We also altered some relations to these tables:

 class User:
     notifications = models.ManyToManyField(
-        'notifications.NoticeType',
-        through='notifications.NoticeSetting',
+        'pinax_notifications.NoticeType',
+        through='pinax_notifications.NoticeSetting',
         blank=True,
         editable=False,
     )
     ...

And the corresponding migrations:

         migrations.AddField(
             model_name='user',
             name='notifications',
-            field=models.ManyToManyField(to='notifications.NoticeType', editable=False, through='notifications.NoticeSetting', blank=True),
+            field=models.ManyToManyField(to='pinax_notifications.NoticeType', editable=False, through='pinax_notifications.NoticeSetting', blank=True),
         ),

[KatherineMichel]

@meshy Thanks for this info. We will take a look at this.