CentOS8 下 python3 + django3連接 mariadb

安裝好django後，用django自動生成一個項目：

$ django-admin startproject mysite

生成的項目如下：

mysite/
    manage.py
    mysite/
        __init__.py
        settings.py
        urls.py
        asgi.py
        wsgi.py

然後在manage.py同級目錄在生成一個應用：

$ python manage.py startapp polls

生成的目錄如下：

polls/
    __init__.py
    admin.py
    apps.py
    migrations/
        __init__.py
    models.py
    tests.py
    views.py

用django建立了以上目錄結構之後，打開 mysite/settings.py，修改DATABASES部分

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'roctest', # 這裏是數據庫名
        'USER': 'root',
        'PASSWORD': 'password',  #這裏是密碼
        'HOST': '127.0.0.1',
        'PORT': '3306',
    }
}

安裝pymysql:

[root@bogon mysite]# pip3 install pymysql
WARNING: Running pip install with root privileges is generally not a good idea. Try `pip3 install --user` instead.
Collecting pymysql
  Using cached https://files.pythonhosted.org/packages/ed/39/15045ae46f2a123019aa968dfcba0396c161c20f855f11dea6796bcaae95/PyMySQL-0.9.3-py2.py3-none-any.whl
Installing collected packages: pymysql
Successfully installed pymysql-0.9.3

在mysite/mysite/init.py裏添加對pymysql的引用：

[root@bogon mysite]# vim  __init__.py 
import pymysql
pymysql.install_as_MySQLdb()

以上工作都做完了，就可以用django的遷移程序生成數據表了：

$ python manage.py migrate

如果出現瞭如下錯誤：

  File "manage.py", line 21, in <module>
    main()
  File "manage.py", line 17, in main
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python3.6/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.6/site-packages/django/core/management/__init__.py", line 377, in execute
    django.setup()
  File "/usr/local/lib/python3.6/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/usr/local/lib/python3.6/site-packages/django/apps/registry.py", line 114, in populate
    app_config.import_models()
  File "/usr/local/lib/python3.6/site-packages/django/apps/config.py", line 211, in import_models
    self.models_module = import_module(models_module_name)
  File "/usr/lib64/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/local/lib/python3.6/site-packages/django/contrib/auth/models.py", line 2, in <module>
    from django.contrib.auth.base_user import AbstractBaseUser, BaseUserManager
  File "/usr/local/lib/python3.6/site-packages/django/contrib/auth/base_user.py", line 47, in <module>
    class AbstractBaseUser(models.Model):
  File "/usr/local/lib/python3.6/site-packages/django/db/models/base.py", line 121, in __new__
    new_class.add_to_class('_meta', Options(meta, app_label))
  File "/usr/local/lib/python3.6/site-packages/django/db/models/base.py", line 325, in add_to_class
    value.contribute_to_class(cls, name)
  File "/usr/local/lib/python3.6/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 "/usr/local/lib/python3.6/site-packages/django/db/__init__.py", line 28, in __getattr__
    return getattr(connections[DEFAULT_DB_ALIAS], item)
  File "/usr/local/lib/python3.6/site-packages/django/db/utils.py", line 207, in __getitem__
    backend = load_backend(db['ENGINE'])
  File "/usr/local/lib/python3.6/site-packages/django/db/utils.py", line 111, in load_backend
    return import_module('%s.base' % backend_name)
  File "/usr/lib64/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 37, in <module>
    raise ImproperlyConfigured('mysqlclient 1.3.13 or newer is required; you have %s.' % Database.__version__)
django.core.exceptions.ImproperlyConfigured: mysqlclient 1.3.13 or newer is required; you have 0.9.3.

編輯文件：
/usr/local/lib/python3.6/site-packages/django/db/backends/mysql/base.py
註釋掉以下兩行：

#if version < (1, 3, 13):
#    raise ImproperlyConfigured('mysqlclient 1.3.13 or newer is required; you have %s.' % Database.__version__)

再次運行django的遷移命令：

[carrousel@bogon mysite]$ python3 manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK
  Applying admin.0003_logentry_add_action_flag_choices... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying auth.0008_alter_user_username_max_length... OK
  Applying auth.0009_alter_user_last_name_max_length... OK
  Applying auth.0010_alter_group_name_max_length... OK
  Applying auth.0011_update_proxy_permissions... OK
  Applying sessions.0001_initial... OK

大功告成！