[PYTHON] Put an index on a column that causes sushi beer problems with Django1.7 + MySQL

Purpose

Use utf8mb4 with Django1.7 + MySQL5.5 or above

If you do it normally

settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'hoge',
        'USER': 'hoge',
        'OPTIONS': {
            'charset': 'utf8mb4',
        }
    }
}

models.py

from django.db import models

class User(models.Model):
    screen_name = models.CharField(max_length=255, unique=True)

Since Migration can be used from Django 1.7 series, use it to define Model

create-db

create database hoge DEFAULT CHARSET utf8mb4;

shell

$ python manage.py makemigrations
$ python manage.py migrate

> django.db.utils.OperationalError: (1709, 'Index column size too large. The maximum column size is 767 bytes.')

A common InnoDB index size issue

Solution

http://blog.kamipo.net/entry/2012/11/13/102024 It's good to use ʻinnodb_large_prefix` as it is around here

my.cnf

[client]
default-character-set = utf8mb4

[mysqld]
character-set-server = utf8mb4
innodb_file_format = Barracuda
innodb_file_per_table = 1
innodb_large_prefix

But how do you specify ROW_FORMAT?

ROW_FORMAT specification method 1

http://qiita.com/miyagi389/items/ffc9918fd8ef2f2a1a45

However, this is not reflected in the Model created by migrations! !!

ROW_FORMAT specification method 2

manage.py

#!/usr/bin/env python
# coding: utf-8
from __future__ import unicode_literals
import os
import sys

if __name__ == "__main__":
    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "testapp.settings")

    from django.db.backends.mysql.schema import DatabaseSchemaEditor
    DatabaseSchemaEditor.sql_create_table += " ROW_FORMAT=DYNAMIC"

    from django.core.management import execute_from_command_line

    execute_from_command_line(sys.argv)

ROW_FORMAT = DYNAMIC is now applied even in migrate!

Supplement

Depending on the module you want to include in Django Some of them do not support migration, so use both in combination.