sqlmigrate does not quote default string values

[Michael Grijalva]

Not sure if this is considered a bug, but the SQL output from sqlmigrate contains a small syntax error with default string values:

Add a new column as so:

class City(models.Model):
    ...
    name = models.CharField(max_length=100, default='a b c d')

Create migration, and run sqlmigrate command:

BEGIN;
--
-- Add field name to city
--
ALTER TABLE `map_city` ADD COLUMN `name ` varchar(100) DEFAULT a b c d NOT NULL;
ALTER TABLE `map_city` ALTER COLUMN `name ` DROP DEFAULT;
COMMIT;

Notice 'a b c d' is missing quotes. When this migration is actually applied it runs through cursor.execute, which properly quotes the value.

I realize sqlmigrate is only for getting a preview of the SQL, but other parts like the table name and columns are correctly quoted, so why not the default?

[Tim Graham]

It looks like a bug at first glance. I encourage you to look at Django's source code and try to confirm and fix it.

[Michael Grijalva]

Ok thank you. I will dig into it more.

[Markus Holtermann]

I gave it a quick look, but I can't reproduce this issue on the current master branch for SQLite3, PostgreSQL or MySQL. Can you give us more information when you report the issue please, such as Django version, database + version, database driver + version, and anything you think might be helpful. Thank you

/Markus

[Michael Grijalva]

Finally had some time to check again. I initially noticed this issue with Django 1.7 + MySQL, but I retested with the latest version of Django:

Django==1.10.5 (latest version from pip)

MySQL-python==1.2.5

On Python2.7.13 with MySQL 5.7.10 (installed via homebrew). I also tried mysqlclient (1.3.9), same issue. I dug into the Django source, and I see the value going through quote_value here: https://github.com/django/django/blob/master/django/db/backends/mysql/schema.py#L30

I believe I found the issue:

>>> import MySQLdb.converters

>>> print MySQLdb.escape('a b c d', MySQLdb.converters.conversions)

'a b c d'

>>> print MySQLdb.escape(u'a b c d', MySQLdb.converters.conversions)

a b c d

Inside quote_value, Django passes a unicode object for the value arg, and MySQLdb fails to quote it properly. With this, it appears to be a bug with mysql-python itself, or my mysql version?