reliably upgrading my plugins to the new django-cms 3.0 table names

0001_old_migration.py

"""
Do not rename the table for plugins in the first "create" migration.

OR: if you do... make the create table statement only run if the table does not already exist.
"""
class Migration():
  
  def forwards(self, orm):
    # ...
  
  def backwards(self, orm):
    # ...

0002_old_migration.py

from . import rename_tables_new_to_old

class Migration():
  cms_plugin_table_mapping = (
        # (old_name, new_name),
        ('cmsplugin_filerfile', 'cmsplugin_filer_file_filerfile'),
  )
  
  def forwards(self, orm):
    rename_tables_new_to_old(db, self.cms_plugin_table_mapping)
    # ...
  
  def backwards(self, orm):
    rename_tables_new_to_old(db, self.cms_plugin_table_mapping)
    # ...

0003_cms3.py

from . import rename_tables_new_to_old, rename_tables_old_to_new

class Migration():
  cms_plugin_table_mapping = (
        # (old_name, new_name),
        ('cmsplugin_filerfile', 'cmsplugin_filer_file_filerfile'),
  )
  
  def forwards(self, orm):
    rename_tables_old_to_new(db, self.cms_plugin_table_mapping)
    # ...
  
  def backwards(self, orm):
    rename_tables_new_to_old(db, self.cms_plugin_table_mapping)
    # ...

__init__.py

#-*- coding: utf-8 -*-

def rename_tables(db, table_mapping, reverse=False):
    """
    renames tables from source to destination name, if the source exists and the destination does
    not exist yet.
    """
    from django.db import connection
    if reverse:
        table_mapping = [(dst, src) for src, dst in table_mapping]
    table_names = connection.introspection.table_names()
    for source, destination in table_mapping:
        if source in table_names and destination in table_names:
            print u"    WARNING: not renaming {0} to {1}, because both tables already exist.".format(source, destination)
        elif source in table_names and destination not in table_names:
            print u"     - renaming {0} to {1}".format(source, destination)
            db.rename_table(source, destination)


def rename_tables_old_to_new(db, table_mapping):
    return rename_tables(db, table_mapping, reverse=False)


def rename_tables_new_to_old(db, table_mapping):
    return rename_tables(db, table_mapping, reverse=True)

helps a lot!