NameError: name '_mysql' is not defined after setting change to mysql
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I have a running Django blog with sqlite3 db at my local machine. What I want is to
Before I ran into the first step, I jumped into the second first. I followed this web page (on MacOS). I created databases called djangolocaldb
on root user and have those infos in /etc/mysql/my.cnf
like this:
# /etc/mysql/my.cnf [client] database=djangolocaldb user=root password=ROOTPASSWORD default-character-set=utf8
Of course I created db, but not table within it.
mysql> show databases; +--------------------+ | Database | +--------------------+ | djangolocaldb | | employees | | information_schema | | mydatabase | | mysql | | performance_schema | | sys | +--------------------+ 7 rows in set (0.00 sec)
I changed settings.py
like this as the web page suggested. Here's how:
# settings.py ... # Database # https://docs.djangoproject.com/en/3.0/ref/settings/#databases DATABASES = { 'default': { 'ENGINE': 'django.db.backends.mysql', #'NAME': os.path.join(BASE_DIR, 'db.sqlite3'), 'OPTIONS' : { 'read_default_file': '/etc/mysql/my.cnf', } } } ...
Now, when I ran python manage.py runserver
with my venv
activated, I got a brutal traceback like this(I ran python manage.py migrate
first, and the traceback looked almost the same anyway):
(.venv) ➜ django-local-blog git:(master) ✗ python manage.py runserver Watching for file changes with StatReloader Exception in thread django-main-thread: Traceback (most recent call last): File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/MySQLdb/__init__.py", line 18, in <module> from . import _mysql ImportError: dlopen(/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/MySQLdb/_mysql.cpython-37m-darwin.so, 2): Library not loaded: @rpath/libmysqlclient.21.dylib Referenced from: /Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/MySQLdb/_mysql.cpython-37m-darwin.so Reason: image not found During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/Users/gwanghyeongim/.pyenv/versions/3.7.6/lib/python3.7/threading.py", line 926, in _bootstrap_inner self.run() File "/Users/gwanghyeongim/.pyenv/versions/3.7.6/lib/python3.7/threading.py", line 870, in run self._target(*self._args, **self._kwargs) File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/utils/autoreload.py", line 53, in wrapper fn(*args, **kwargs) File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/core/management/commands/runserver.py", line 109, in inner_run autoreload.raise_last_exception() File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/utils/autoreload.py", line 76, in raise_last_exception raise _exception[1] File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/core/management/__init__.py", line 357, in execute autoreload.check_errors(django.setup)() File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/utils/autoreload.py", line 53, in wrapper fn(*args, **kwargs) File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/__init__.py", line 24, in setup apps.populate(settings.INSTALLED_APPS) File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/apps/registry.py", line 114, in populate app_config.import_models() File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/apps/config.py", line 211, in import_models self.models_module = import_module(models_module_name) File "/Users/gwanghyeongim/.pyenv/versions/3.7.6/lib/python3.7/importlib/__init__.py", line 127, in import_module return _bootstrap._gcd_import(name[level:], package, level) File "<frozen importlib._bootstrap>", line 1006, in _gcd_import File "<frozen importlib._bootstrap>", line 983, in _find_and_load File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked File "<frozen importlib._bootstrap>", line 677, in _load_unlocked File "<frozen importlib._bootstrap_external>", line 728, in exec_module File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/contrib/auth/models.py", line 2, in <module> from django.contrib.auth.base_user import AbstractBaseUser, BaseUserManager File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/contrib/auth/base_user.py", line 47, in <module> class AbstractBaseUser(models.Model): File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/db/models/base.py", line 121, in __new__ new_class.add_to_class('_meta', Options(meta, app_label)) File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/db/models/base.py", line 325, in add_to_class value.contribute_to_class(cls, name) File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/db/models/options.py", line 208, in contribute_to_class self.db_table = truncate_name(self.db_table, connection.ops.max_name_length()) File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/db/__init__.py", line 28, in __getattr__ return getattr(connections[DEFAULT_DB_ALIAS], item) File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/db/utils.py", line 207, in __getitem__ backend = load_backend(db['ENGINE']) File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/db/utils.py", line 111, in load_backend return import_module('%s.base' % backend_name) File "/Users/gwanghyeongim/.pyenv/versions/3.7.6/lib/python3.7/importlib/__init__.py", line 127, in import_module return _bootstrap._gcd_import(name[level:], package, level) File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/django/db/backends/mysql/base.py", line 16, in <module> import MySQLdb as Database File "/Users/gwanghyeongim/Documents/py/coreyMS_pj/django-local-blog/.venv/lib/python3.7/site-packages/MySQLdb/__init__.py", line 24, in <module> version_info, _mysql.version_info, _mysql.__file__ NameError: name '_mysql' is not defined
So this NameError: name '_mysql' is not defined
is the problem. I installed mysqlclient
before, changed settings.py
, made db in mysql, but none of the steps made it any helpful yet.
And I noticed that even I changed my settings.py
back to sqlite3, my blog spit the same _mysql not defined error. So I ended up reverting my commit and now I'm back to sqlite3 (at least my blog is running with it).
I'm guessing it could be that I didn't convert data first, but I'm not 100% sure of it.
Any suggestion would be much appreciated. Thank you in advance!
EDITED on Aug 18, 2020
If you still see _mysql not defined
error when you run python manage.py migrate
somehow, check out the following two settings.
mysqlclient
when you run pip freeze
in your python virtual environment like so,(.venv) ➜ SqlDjango git:(master) ✗ pip freeze ... Django==3.0.8 mysqlclient==2.0.1 ...
make sure you installed mysqlclient
in your python virtual environment, not mysql-client
. The former supports python3, whereas the latter supports python2, which I assume is not probably what you want.
~/.zshrc
for zsh, or ~/.bashrc
or ~/.bash_profile
for bash etc.)export DYLD_LIBRARY_PATH=/usr/local/mysql/lib/
After that, apply change by runnig source ~/.your_shell_config_file
. See python manage.py migrate
works.
17 Answers
This did the job for me! Just install libmysqlclient-dev (sudo apt-get install libmysqlclient-dev
for Ubuntu). Sometimes, the lib files simply are missing even if you just installed mysql. :)
So, I'm answering my own question. Since my blog has database, I gave it a shot to make another project without db, start fresh.
What I noticed was there's a problem importing MySQLdb
module(sub module of mysqlclient) with this traceback: Library not loaded: @rpath/libmysqlclient.21.dylib
.
For browsing a few hours I realised that for some reason Mac security setting keeps this from being imported properly.
On mysqlclient
library github I found one issue reporting the same as mine. It suggests I run cp -r /usr/local/mysql/lib/* /usr/local/lib/
. After this I set settings.py
for django.db.backends.mysql
, ran python manage.py migrate
and it worked. So for empty database, this could be a solution. Still struggling with database one though.
I use
- MacOS Catalina 10.15.6
- pyenv
this worked for me:
add this to PATH:
export DYLD_LIBRARY_PATH="/usr/local/mysql/lib:$PATH"
So as a full answer:
If you use the python package mysqlclient you still need to install the mysql client from Oracle/MySQL. This contains the C-library that the python package uses. To make things more confusing: the python package is in fact written in C for speed increases. To install this library on MacOS:
% brew install mysql-client
There's also a pure python package, with a more attractive MIT License, which can be a solution if your company or client does not allow GPL. However, it's not officially supported and some subtle bugs can occur in between releases. YMMV.
1I was facing the same problem on my MacOS (Big Sur) and I fixed it by doing this cp -r /usr/local/mysql/lib/* /usr/local/lib/
This solved the issue for me:
Since Python3 is not able to connect with Python through mysqldb, you need to install an additional module to fix things. installing mysqlclient caused me to have the same NameError: : name '_mysql' is not defined
problem.
However, by using pymysql
, and adding the code line pymysql.install_as_MySQLdb()
at the top of my Flask
app, I managed to get it running without any errors!
More info on mysql modules
1I just had a similar problem and couldnt find solution for hours
>>> import MySQLdb Traceback (most recent call last): File "/{path-to-venv}/lib/python3.7/site-packages/MySQLdb/__init__.py", line 18, in <module> from . import _mysql ImportError: /{path-to-venv}/lib/python3.7/site-packages/MySQLdb/_mysql.cpython-37m-arm-linux-gnueabihf.so: failed to map segment from shared object During handling of the above exception, another exception occurred: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/{path-to-venv}/lib/python3.7/site-packages/MySQLdb/__init__.py", line 24, in <module> version_info, _mysql.version_info, _mysql.__file__ NameError: name '_mysql' is not defined
so if anyone here is like me and has the virtualenv on a mounted partition/disk, you have to mount it with exec, thats the whole problem.
Remount the partition with executable permission as explained in: https://askubuntu.com/questions/311438/how-to-make-tmp-executable.
If you mount the drive with fstab, see: https://askubuntu.com/questions/678857/fstab-doesnt-mount-with-exec.
(well, that was 10hours of trying and debugging well spend lol)
1I agree with Melvyn.
you can see your MySQL library link by typing like:
(quantum) chaiyudeMacBook-Pro:quantum chaiyu$ python Python 3.8.7 (v3.8.7:6503f05dd5, Dec 21 2020, 12:45:15) [Clang 6.0 (clang-600.0.57)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import MySQLdb as Database Traceback (most recent call last): File "/Users/chaiyu/Envs/quantum/lib/python3.8/site-packages/MySQLdb/__init__.py", line 18, in <module> from . import _mysql ImportError: dlopen(/Users/chaiyu/Envs/quantum/lib/python3.8/site-packages/MySQLdb/_mysql.cpython-38-darwin.so, 2): Library not loaded: /usr/local/opt/mysql/lib/libmysqlclient.21.dylib Referenced from: /Users/chaiyu/Envs/quantum/lib/python3.8/site-packages/MySQLdb/_mysql.cpython-38-darwin.so Reason: image not found During handling of the above exception, another exception occurred: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/Users/chaiyu/Envs/quantum/lib/python3.8/site-packages/MySQLdb/__init__.py", line 24, in <module> version_info, _mysql.version_info, _mysql.__file__ NameError: name '_mysql' is not defined
then type:
(quantum) chaiyudeMacBook-Pro:quantum chaiyu$ otool -L /Users/chaiyu/Envs/quantum/lib/python3.8/site-packages/MySQLdb/_mysql.cpython-38-darwin.so /Users/chaiyu/Envs/quantum/lib/python3.8/site-packages/MySQLdb/_mysql.cpython-38-darwin.so: /usr/local/opt/mysql/lib/libmysqlclient.21.dylib (compatibility version 21.0.0, current version 21.0.0) /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.250.1) (quantum) chaiyudeMacBook-Pro:quantum chaiyu$ ls -l /usr/local/opt/mysql/lib/libmysqlclient.21.dylib ls: /usr/local/opt/mysql/lib/libmysqlclient.21.dylib: No such file or directory
and then, I found the library MySQL linked to does not exist.
I had the same error and it was working for a while. I did an update on MacOS BigSur then it stopped working with this error.
To fix this for me it was a simple uninstall reinstall of both django and mysqlclient.
The uninstall/reinstall of just mysqlclient itself did not do the trick. Also the order may help. Here are the commands in the order i did it in:
pip uninstall mysqlclient pip uninstall django pip install django pip install mysqlclient
Note: this will install the latest versions, so if you have specific versions, make sure you install those versions.
0This worked for me
brew install mysql
for mac
Assume you are activating Python 3 venv
brew install mysql pip install mysqlclient
for ubuntu interminal run
sudo apt-get install python3-dev default-libmysqlclient-dev build-essential pip install mysqlclient
for # Red Hat / CentOS
sudo yum install python3-devel mysql-devel pip install mysqlclient
Finally after spending like decade on this issue found a good answer.
mysqlclient
is a Python 3 compatible fork of the original Python MySQL driver, MySQLdb
. It still provides a Python module called MySQLdb
. On install, it compiles against either the MariaDB client library or MySQL client library - whichever one you have installed.
Solution Found Here By Adam(Genius Guy)
From Apple Silicon M1 Mac and a conda environment the only solution that worked for me was to use Miniforge installation, which is comparable to Miniconda, but with conda-forge as the default channel. There is an Apple Silicon option that solved the problem for me: https://github.com/Haydnspass/miniforge#download
(Solution from https://towardsdatascience.com/using-conda-on-an-m1-mac-b2df5608a141)
2If you're using bash, use:
open -t .bash_profile
and add the following:
export DYLD_LIBRARY_PATH="/usr/local/mysql/lib:$PATH"
If you're using Zsh, use:
open -t ~/.zshrc
and add the following:
export DYLD_LIBRARY_PATH="/usr/local/mysql/lib:$PATH"
although I used _mysql for 10 years, the MySQL website tells the recommended way for Python 3 at: https://dev.mysql.com/doc/connector-python/en/preface.html
Conversion may take some time, but for me less than an hour. Here an example with new code:
import mysql.connector cnx = mysql.connector.connect(user='mensfort', password='zhongcan', host='127.0.0.1', database='restaurant') cursor = cnx.cursor() cursor.execute('select dongle from personnel') for dongle in cursor: print(dongle) cursor.close() cnx.close()
Please use your own password, database name, queries, this is just an example.
Please do UNINSTALL this. This is not working for me:
pip uninstall mysql-connector
Please INSTALL this first. It works great:
pip install mysql-connector-python
On a MacBook Pro M1 macOS Monterey, running this command didn't work:
export DYLD_LIBRARY_PATH="/usr/local/mysql/lib:$PATH"
But this worked for me:
export DYLD_LIBRARY_PATH=/usr/local/mysql/lib
Reverting back from MySQL Server 8.x.x to 5.7.x worked for me.
Django supports MySQL 5.5.x - 5.7.x. MySQL 8 and later aren’t supported.
Found @ Django Docs
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