boards/migrations/0009_post_thread.py

# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import models, migrations


class Migration(migrations.Migration):

    def first_thread_to_thread(apps, schema_editor):
        Post = apps.get_model('boards', 'Post')
        for post in Post.objects.all():
            post.thread = post.threads.first()
            post.save(update_fields=['thread'])


    dependencies = [
        ('boards', '0008_auto_20150205_1304'),
    ]

    operations = [
        migrations.AddField(
            model_name='post',
            name='thread',
            field=models.ForeignKey(on_delete=models.CASCADE, related_name='pt+', to='boards.Thread', default=None, null=True),
            preserve_default=False,
        ),
        migrations.RunPython(first_thread_to_thread),
    ]