django3踩坑

 

1、创建django项目

$ django-admin startproject DailyFresh　　

2、进入项目目录

$ cd DailyFresh

3、启动项目

$ python manage.py runserver
Watching for file changes with StatReloader
[28/Mar/2020 17:34:35] "GET / HTTP/1.1" 200 16351
[28/Mar/2020 17:34:35] "GET /static/admin/css/fonts.css HTTP/1.1" 200 423
[28/Mar/2020 17:34:35] "GET /static/admin/fonts/Roboto-Bold-webfont.woff HTTP/1.1" 200 86184
[28/Mar/2020 17:34:35] "GET /static/admin/fonts/Roboto-Regular-webfont.woff HTTP/1.1" 200 85876
[28/Mar/2020 17:34:35] "GET /static/admin/fonts/Roboto-Light-webfont.woff HTTP/1.1" 200 85692
Not Found: /favicon.ico
[28/Mar/2020 17:34:39] "GET /favicon.ico HTTP/1.1" 404 1976
Performing system checks...

4、创建cart、goods、order、user4个应用

$ python manage.py startapp cart

Administrator@PC-20171101OWRR MINGW64 /d/wordspace/python_project/DailyFresh
$ python manage.py startapp goods

Administrator@PC-20171101OWRR MINGW64 /d/wordspace/python_project/DailyFresh
$ python manage.py startapp order

Administrator@PC-20171101OWRR MINGW64 /d/wordspace/python_project/DailyFresh
$ python manage.py startapp user

5、在settings中设置INSTALLED_APPS，和DATABASES（前提是现在数据库中建立daily_fresh数据库）

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'goods',
    'order',
    'cart',
    'user',
]

先在mysql中建立daily_fresh数据库

 

 然后在settings中设置DATABASES;

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME':'daily_fresh',
        'USER':'root',//数据库用户名
        'PASSWORD':'123456',//数据库密码
        'HOST':'localhost',
        'PORT':'3306',
    }
}

　　

　

6、用python manage.py migrate创建数据库表

$ python 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

　　至此项目架构已经搭好。

 

7、之后自己开始在每一个模块内建立数据模型。以下是在user应用的model.py中建立的模型。该模型对系统自带的user模型进行了扩展，继承了AbstractUser,

# Create your models here.
class User(AbstractUser,BaseModel):
    """用户模型"""
    def generate_active_token(self):
        """生成用户签名字符串"""
        serializer = Serializer(settings.SECRET_KEY, 3600)
        info = {'confirm':self.id}
        token = serializer.dump(info)
        return token.decode()

    class Meta:
        db_table = 'user'
        verbose_name = '用户'
        verbose_name_plural = verbose_name

8、下一步想让数据模型写入数据库内，但在执行　python manage.py makemigrations时提示错误　

$ python manage.py makemigrations
SystemCheckError: System check identified some issues:

ERRORS:
auth.User.groups: (fields.E304) Reverse accessor for 'User.groups' clashes with reverse accessor for 'User.groups'.
        HINT: Add or change a related_name argument to the definition for 'User.groups' or 'User.groups'.
auth.User.user_permissions: (fields.E304) Reverse accessor for 'User.user_permissions' clashes with reverse accessor for 'User.user_permissions'.
        HINT: Add or change a related_name argument to the definition for 'User.user_permissions' or 'User.user_permissions'.
user.User.groups: (fields.E304) Reverse accessor for 'User.groups' clashes with reverse accessor for 'User.groups'.
        HINT: Add or change a related_name argument to the definition for 'User.groups' or 'User.groups'.
user.User.user_permissions: (fields.E304) Reverse accessor for 'User.user_permissions' clashes with reverse accessor for 'User.user_permissions'.
        HINT: Add or change a related_name argument to the definition for 'User.user_permissions' or 'User.user_permissions'.

解决方案：

需要在setting中重载AUTH_USER_MODEL

# 格式为 "<django_app名>.<model名>"
AUTH_USER_MODEL = "user.User"

如下调整后，执行正常

 

$ python manage.py makemigrations
Migrations for 'user':
  user\migrations\0001_initial.py
    - Create model User
    - Create model Address

9、但在执行python manage.py migrate写入数据库时，又提示错误了　

$ python manage.py migrate
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 "C:\Python36\lib\site-packages\django\core\management\__init__.py", line 401, in execute_from_command_line
    utility.execute()
  File "C:\Python36\lib\site-packages\django\core\management\__init__.py", line 395, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "C:\Python36\lib\site-packages\django\core\management\base.py", line 328, in run_from_argv
    self.execute(*args, **cmd_options)
  File "C:\Python36\lib\site-packages\django\core\management\base.py", line 369, in execute
    output = self.handle(*args, **options)
  File "C:\Python36\lib\site-packages\django\core\management\base.py", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File "C:\Python36\lib\site-packages\django\core\management\commands\migrate.py", line 89, in handle
    executor.loader.check_consistent_history(connection)
  File "C:\Python36\lib\site-packages\django\db\migrations\loader.py", line 299, in check_consistent_history
    connection.alias,
django.db.migrations.exceptions.InconsistentMigrationHistory: Migration admin.0001_initial is applied before its dependency user.0001_initial on database 'default'.

经查是因为在第6步已经执行过python manage.py migrate，现在再执行写不进去了。我的解决办法就是将之前生成的daily_fresh数据库全部删除，然后重新建立数据库，再执行python manage.py migrate，问题就解决了。这个方法主要参考了这个链接（https://stackoverflow.com/questions/42412409/inconsistentmigrationhistory-error-with-custom-django-user-model.）

1）删除数据库

2）重新建立数据库

3）再执行python manage.py migrate 。注意此处没有先执行python manage.py makemigrations，因为执行了也提示no changes detected

$ python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions, user
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0001_initial... 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 user.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 sessions.0001_initial... OK

 

 

　

$ django-admin startproject DailyFresh