django admin reises FieldDoesNotExist on renamed field

Question

sorry for newbie question, but I can't understand why this happen and how to fix it. I created Comment model

class Migration(migrations.Migration):

dependencies = [
    ('myblog', '0001_initial'),
]

operations = [
    migrations.CreateModel(
        name='Comment',
        fields=[
            ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
            ('text', models.TextField()),
            ('pub_date', models.DateTimeField(default=django.utils.timezone.now, verbose_name='date published')),
            ('lft', models.PositiveIntegerField(db_index=True, editable=False)),
            ('rght', models.PositiveIntegerField(db_index=True, editable=False)),
            ('tree_id', models.PositiveIntegerField(db_index=True, editable=False)),
            ('level', models.PositiveIntegerField(db_index=True, editable=False)),
            ('parent', mptt.fields.TreeForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='children', to='myblog.Comment')),
        ],
        options={
            'abstract': False,
        },
    ),
]

After that I realized I forgot FK to Article.

class Comment(MPTTModel):
    text = models.TextField()
    parent_article = models.ForeignKey(Article, on_delete=models.CASCADE)
    parent_comment = TreeForeignKey('self', null=True, blank=True, related_name='children', db_index=True)
    pub_date = models.DateTimeField('date published', default=timezone.now)

    class MPTTMeta:
        order_insertion_by = ['pub_date']


class Migration(migrations.Migration):

dependencies = [
    ('myblog', '0002_comment'),
]

operations = [
    migrations.RenameField(
        model_name='comment',
        old_name='parent',
        new_name='parent_comment',
    ),
    migrations.AddField(
        model_name='comment',
        name='parent_article',
        field=models.ForeignKey(default=0, on_delete=django.db.models.deletion.CASCADE, to='myblog.Article'),
        preserve_default=False,
    ),
]

And now I can't add comment at admin site, because it reises

 FieldDoesNotExist at /admin/myblog/comment/add/
 Comment has no field named 'parent'

How can I fix it? Do I have to delete Comment model and start from the beggining?

I understand I renamed FK, but django don't. How admin get list of fields? From migration, not from model?

Thank you.

Answer 1

This is because while adding the foreign key, you have renamed it too!

migrations.RenameField(
    model_name='comment',
    old_name='parent',
    new_name='parent_comment',
),

Now the field is called parent_comment either roll back the migration or use the new field name. It is also possible to rename parent_comment to parent again!