MySQL "incorrect string value" error when save unicode string in Django

None of these answers solved the problem for me. The root cause being:

You cannot store 4-byte characters in MySQL with the utf-8 character set.

MySQL has a 3 byte limit on utf-8 characters (yes, it's wack, nicely summed up by a Django developer here)

To solve this you need to:

1. Change your MySQL database, table and columns to use the utf8mb4 character set (only available from MySQL 5.5 onwards)
2. Specify the charset in your Django settings file as below:

settings.py

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

Note: When recreating your database you may run into the 'Specified key was too long' issue.

The most likely cause is a CharField which has a max_length of 255 and some kind of index on it (e.g. unique). Because utf8mb4 uses 33% more space than utf-8 you'll need to make these fields 33% smaller.

In this case, change the max_length from 255 to 191.

Alternatively you can edit your MySQL configuration to remove this restriction but not without some django hackery

UPDATE: I just ran into this issue again and ended up switching to PostgreSQL because I was unable to reduce my VARCHAR to 191 characters.

I had the same problem and resolved it by changing the character set of the column. Even though your database has a default character set of utf-8 I think it's possible for database columns to have a different character set in MySQL. Here's the SQL QUERY I used:

 ALTER TABLE database.table MODIFY COLUMN col VARCHAR(255)
 CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL;

If you have this problem here's a python script to change all the columns of your mysql database automatically.

#! /usr/bin/env python
import MySQLdb
host = "localhost"
passwd = "passwd"
user = "youruser"
dbname = "yourdbname"
db = MySQLdb.connect(host=host, user=user, passwd=passwd, db=dbname)
cursor = db.cursor()
cursor.execute("ALTER DATABASE `%s` CHARACTER SET 'utf8' COLLATE 'utf8_unicode_ci'" % dbname)
sql = "SELECT DISTINCT(table_name) FROM information_schema.columns WHERE table_schema = '%s'" % dbname
cursor.execute(sql)
results = cursor.fetchall()
for row in results:
 sql = "ALTER TABLE `%s` convert to character set DEFAULT COLLATE DEFAULT" % (row[0])
 cursor.execute(sql)
db.close()

If it's a new project, I'd just drop the database, and create a new one with a proper charset:

CREATE DATABASE <dbname> CHARACTER SET utf8;

I just figured out one method to avoid above errors.

Save to database

user.first_name = u'Rytis'.encode('unicode_escape')
user.last_name = u'Slatkevičius'.encode('unicode_escape')
user.save()
>>> SUCCEED
print user.last_name
>>> Slatkevi\u010dius
print user.last_name.decode('unicode_escape')
>>> Slatkevičius

Is this the only method to save strings like that into a MySQL table and decode it before rendering to templates for display?

You can change the collation of your text field to UTF8_general_ci and the problem will be solved.

Notice, this cannot be done in Django.

Improvement to @madprops answer - solution as a django management command:

import MySQLdb
from django.conf import settings
from django.core.management.base import BaseCommand
class Command(BaseCommand):
 def handle(self, *args, **options):
 host = settings.DATABASES['default']['HOST']
 password = settings.DATABASES['default']['PASSWORD']
 user = settings.DATABASES['default']['USER']
 dbname = settings.DATABASES['default']['NAME']
 db = MySQLdb.connect(host=host, user=user, passwd=password, db=dbname)
 cursor = db.cursor()
 cursor.execute("ALTER DATABASE `%s` CHARACTER SET 'utf8' COLLATE 'utf8_unicode_ci'" % dbname)
 sql = "SELECT DISTINCT(table_name) FROM information_schema.columns WHERE table_schema = '%s'" % dbname
 cursor.execute(sql)
 results = cursor.fetchall()
 for row in results:
 print(f'Changing table "{row[0]}"...')
 sql = "ALTER TABLE `%s` convert to character set DEFAULT COLLATE DEFAULT" % (row[0])
 cursor.execute(sql)
 db.close()

Hope this helps anybody but me :)

You aren't trying to save unicode strings, you're trying to save bytestrings in the UTF-8 encoding. Make them actual unicode string literals:

user.last_name = u'Slatkevičius'

or (when you don't have string literals) decode them using the utf-8 encoding:

user.last_name = lastname.decode('utf-8')

Simply alter your table, no need to any thing. just run this query on database. ALTER TABLE table_nameCONVERT TO CHARACTER SET utf8

it will definately work.

• python
• mysql
• django
• unicode
• utf-8