Adds Meta option db_column_prefix that prepends a per-model prefix to db column names

models.py

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

# This hack adds a new Meta option "db_column_prefix". If not None all
# database columns in a model will be prepended with this prefix (the
# database columns, not the attributes). See Person model for an
# example.
#
# Issues:
# - How to set a prefix for a m2m table?  - If "through" argument is
#   not specified on a M2MField, Django automatically adds a model
#   representing the m2m table (search for
#   create_many_to_many_intermediary_model). It's not easy to hook
#   into this process without really ugly hacks. So the easiest way is
#   to use the "through" argument...
# - Get rid of monkey patching
# - If your db admin is sitting next to you, you need to have prefixes
#   for tables generated by other apps (like auth) too. With this
#   approach there's currently no way to achieve this. It'd be great
#   to have a central place for building table and column names (maybe
#   the db backend?)

from django.db import models

# Monkey-patch DEFAULT_NAMES for Meta options. Otherwise
# db_column_prefix would raise an error.
from django.db.models import options
options.DEFAULT_NAMES += ("db_column_prefix",)


class ColumnPrefixModelMeta(models.base.ModelBase):
    """Model metaclass that adds Meta.db_column_prefix to a db column name."""

    def __new__(cls, name, bases, attrs):
        new_cls = super(ColumnPrefixModelMeta, cls).__new__(
            cls, name, bases, attrs)
        prefix = getattr(new_cls._meta, "db_column_prefix", None)
        # db_column_prefix on abstract base classes will be ignored.
        if not new_cls._meta.abstract and prefix is not None:
            # Shamelessly stolen from ModelBase.__new__:
            new_fields = new_cls._meta.local_fields + \
                         new_cls._meta.local_many_to_many + \
                         new_cls._meta.virtual_fields
            for field in new_fields:
                if field.db_column is None:
                    field.db_column = field.get_attname()
                if not field.db_column.startswith(prefix):
                    field.db_column = "%s%s" % (prefix, field.db_column)
                # This sets field.column which is needed for build SQL
                # statements
                field.set_attributes_from_name(field.name)
        return new_cls


class Person(models.Model):

    __metaclass__ = ColumnPrefixModelMeta

    first_name = models.CharField(max_length=30)
    last_name = models.CharField(max_length=30)
    created = models.DateTimeField(
        auto_now_add=True, db_column="crdate")
    modified = models.DateTimeField(
        auto_now=True, db_column="upddate")

    class Meta:
        # The following column names will be used: per_first_name,
        # per_last_name, per_crdate, per_uppdate.
        db_column_name = "per_"