将数据库引擎更改为 MySQL。现在 Django 不创建表

Question

我有一个带有标准 sqlite3 数据库的 Django 应用程序。现在我想使用 MySQL。所以我在 settings.py 中更改了我的 DATABASES，它运行良好，但我不能运行服务器，因为它说

django.db.utils.InternalError: (1049, "Unknown database 'django'")

所以我在客户端创建了这个数据库，现在显示

django.db.utils.ProgrammingError: (1146, "Table 'django.Cat' doesn't exist")

好像我必须自己创建所有表，这是我能做的最糟糕的变体。

#settings.py
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'OPTIONS': {
            'read_default_file': '/path/to/db.conf',
        },
    }
}

和

#conf.db
[client]
database = django
host = localhost
user = DjangoUser
password = password_you_cant_guess
default-character-set = utf8

如何让 Django 创建我所有的表？

我什至不能运行 python3 manage.py 使用任何命令，因为它给了我这个例外。

回溯：

Traceback (most recent call last):
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 74, in execute
    return self.cursor.execute(query, args)
  File "/path/to/project/venv/lib/python3.6/site-packages/MySQLdb/cursors.py", line 209, in execute
    res = self._query(query)
  File "/path/to/project/venv/lib/python3.6/site-packages/MySQLdb/cursors.py", line 315, in _query
    db.query(q)
  File "/path/to/project/venv/lib/python3.6/site-packages/MySQLdb/connections.py", line 239, in query
    _mysql.connection.query(self, query)
MySQLdb._exceptions.ProgrammingError: (1146, "Table 'django.Cat' doesn't exist")

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "manage.py", line 21, in <module>
    main()
  File "manage.py", line 17, in main
    execute_from_command_line(sys.argv)
  File "/path/to/project/venv/lib/python3.6/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
    utility.execute()
  File "/path/to/project/venv/lib/python3.6/site-packages/django/core/management/__init__.py", line 377, in execute
    django.setup()
  File "/path/to/project/venv/lib/python3.6/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/path/to/project/venv/lib/python3.6/site-packages/django/apps/registry.py", line 122, in populate
    app_config.ready()
  File "/path/to/project/External/apps.py", line 13, in ready
    active_cats = list(Cat.objects.filter(active_cat=True).all())
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/models/query.py", line 276, in __iter__
    self._fetch_all()
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/models/query.py", line 1261, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/models/query.py", line 57, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1151, in execute_sql
    cursor.execute(sql, params)
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 100, in execute
    return super().execute(sql, params)
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "/path/to/project/venv/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 74, in execute
    return self.cursor.execute(query, args)
  File "/path/to/project/venv/lib/python3.6/site-packages/MySQLdb/cursors.py", line 209, in execute
    res = self._query(query)
  File "/path/to/project/venv/lib/python3.6/site-packages/MySQLdb/cursors.py", line 315, in _query
    db.query(q)
  File "/path/to/project/venv/lib/python3.6/site-packages/MySQLdb/connections.py", line 239, in query
    _mysql.connection.query(self, query)
django.db.utils.ProgrammingError: (1146, "Table 'django.Cat' doesn't exist")

Answer 1

您的问题在这里：

File "/path/to/project/External/apps.py", line 13, in ready
    active_cats = list(Cat.objects.filter(active_cat=True).all())

此代码作为初始化过程的一部分执行。这就是阻止您执行任何管理命令的原因。请注意 this is documented with a very clear warning:

Warning

Although you can access model classes as described above, avoid interacting with the database in your ready() implementation. This includes model methods that execute queries (save(), delete(), manager methods etc.), and also raw SQL queries via django.db.connection. Your ready() method will run during startup of every management command. For example, even though the test database configuration is separate from the production settings, manage.py test would still execute some queries against your production database!

将数据库引擎更改为 MySQL。现在 Django 不创建表

Changed DB engine to MySQL. Now Django does not create tables

python

mysql

migration

django

django-database