每个模型是一个Python 类，集成django.db.models.Modle类

该模型的每个属性表示一个数据库表字段

通过API 自动生成数据库访问 .../sign/modles.py 文件，通过模型完成表创建。

 TypeError: ForeignKey.__init__() missing 1 required positional argument: 'on_delete'

在创建一个新模型时 ，出现错误TypeError: ForeignKey.__init__() missing 1 required positional argument: ‘on_delete‘_爱吃龙虾的小黑的博客-CSDN博客

E:\data\python\djaongo_prj\guest>  python manage.py makeigrations sign
Traceback (most recent call last):File "E:\data\python\djaongo_prj\guest\manage.py", line 21, in <module>main()File "E:\data\python\djaongo_prj\guest\manage.py", line 17, in mainexecute_from_command_line(sys.argv)File "D:\software\python3\anconda3\Lib\site-packages\django\core\management\__init__.py", line 442, in execute_from_command_lineutility.execute()File "D:\software\python3\anconda3\Lib\site-packages\django\core\management\__init__.py", line 416, in executedjango.setup()File "D:\software\python3\anconda3\Lib\site-packages\django\__init__.py", line 24, in setupapps.populate(settings.INSTALLED_APPS)File "D:\software\python3\anconda3\Lib\site-packages\django\apps\registry.py", line 116, in populateapp_config.import_models()File "D:\software\python3\anconda3\Lib\site-packages\django\apps\config.py", line 269, in import_modelsself.models_module = import_module(models_module_name)File "D:\software\python3\python310\lib\importlib\__init__.py", line 126, in import_modulereturn _bootstrap._gcd_import(name[level:], package, level)File "<frozen importlib._bootstrap>", line 1050, in _gcd_importFile "<frozen importlib._bootstrap>", line 1027, in _find_and_loadFile "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlockedFile "<frozen importlib._bootstrap>", line 688, in _load_unlockedFile "<frozen importlib._bootstrap_external>", line 883, in exec_moduleFile "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removedFile "E:\data\python\djaongo_prj\guest\sign\models.py", line 20, in <module>class Guest(models.Model):File "E:\data\python\djaongo_prj\guest\sign\models.py", line 21, in Guestevent = models.ForeignKey(Event)  # 关联发布会id
TypeError: ForeignKey.__init__() missing 1 required positional argument: 'on_delete'

 必须要设置级联删除，也就是当你删除一条信息时，会级联的删除所有和这一条信息对应的另一张表的多个信息，也就是指定on_delete=models.CASCADE

event = models.ForeignKey(Event,on_delete=models.CASCADE)  # 关联发布会id

# 嘉宾
class Guest(models.Model):event = models.ForeignKey(Event,on_delete=models.CASCADE)  # 关联发布会idrealname = models.CharField(max_length=64)  # 姓名phone = models.CharField(max_length=16)  # 手机号email = models.EmailField()  # 邮箱sign = models.BooleanField()  # 签到状态create_time = models.DateTimeField(auto_now=True)  # 创建时间（自动获取当前时间）class Meta:unique_together = ('phone', 'event')def __str__(self):return self.realname

 python manage.py makemigrations sign

E:\data\python\djaongo_prj\guest>  python manage.py makemigrations sign
System check identified some issues:WARNINGS:
sign.Event: (models.W042) Auto-created primary key used when not defining a primary key type, by default 'django.db.models.AutoField'.HINT: Configure the DEFAULT_AUTO_FIELD setting or the SignConfig.default_auto_field attribute to point to a subclass of AutoField, e.g. 'django.db.models.BigAutoField'.
sign.Guest: (models.W042) Auto-created primary key used when not defining a primary key type, by default 'django.db.models.AutoField'.HINT: Configure the DEFAULT_AUTO_FIELD setting or the SignConfig.default_auto_field attribute to point to a subclass of AutoField, e.g. 'django.db.models.BigAutoField'.
Migrations for 'sign':sign\migrations\0001_initial.py- Create model Event- Create model Guest

  python manage.py migrate

E:\data\python\djaongo_prj\guest>  python manage.py migrate
System check identified some issues:WARNINGS:
sign.Event: (models.W042) Auto-created primary key used when not defining a primary key type, by default 'django.db.models.AutoField'.HINT: Configure the DEFAULT_AUTO_FIELD setting or the SignConfig.default_auto_field attribute to point to a subclass of AutoField, e.g. 'django.db.models.BigAutoField'.
sign.Guest: (models.W042) Auto-created primary key used when not defining a primary key type, by default 'django.db.models.AutoField'.HINT: Configure the DEFAULT_AUTO_FIELD setting or the SignConfig.default_auto_field attribute to point to a subclass of AutoField, e.g. 'django.db.models.BigAutoField'.
Operations to perform:Apply all migrations: admin, auth, contenttypes, sessions, sign
Running migrations:Applying auth.0012_alter_user_first_name_max_length... OKApplying sign.0001_initial... OKE:\data\python\djaongo_prj\guest>

admin  后台 管理

from django.contrib import admin# Register your models here.
#  admin 后台管理  创建的发布会和嘉宾表示同样可以通过Admin 后台管理
from  django.contrib  import  admin
from  sign.models import   Event ,Guest# Register your models here.
class EventAdmin(admin.ModelAdmin):list_display = ['name', 'status', 'start_time','id']search_fields = ['name']    # 搜索功能list_filter = ['status']    # 过滤器class GuestAdmin(admin.ModelAdmin):list_display = ['realname', 'phone','email','sign','create_time','event_id']list_display_links = ('realname', 'phone') # 显示链接search_fields = ['realname','phone']       # 搜索功能list_filter = ['sign']                 # 过滤器admin.site.register(Event, EventAdmin)
admin.site.register(Guest, GuestAdmin)

Microsoft Windows [版本 10.0.19045.3448]
(c) Microsoft Corporation。保留所有权利。E:\data\python\djaongo_prj\guest>python   manage.py shell
Python 3.10.0 (tags/v3.10.0:b494f59, Oct  4 2021, 19:00:18) [MSC v.1929 64 bit (AMD64)]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.10.0 -- An enhanced Interactive Python. Type '?' for help.In [1]:In [1]:In [1]: from sign.models import Event,GuestIn [2]: Event.objects.all()
Out[2]: <QuerySet [<Event: 小米5发布会>]>In [3]:

from sign.models import Event,Guest  导入模块

 Event.objects.all()   所有对象

配置 MySQL  

 pip  install pymysql

数据库创建表

报错 [Err] 1055 - Expression #1 of ORDER BY

[Err] 1055 - Expression #1 of ORDER BY clause is not in GROUP BY clause and contains nonaggregated column 'information_schema.PROFILING.SEQ' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

[Err] 1055 - Expression #1 of ORDER BY clause is not in GROUP BY clause and contains nonaggregated_Ricardo · M · YUAN的博客-CSDN博客

在配置文件的末尾加上这段代码：
[mysqld]
sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION

CREATE TABLE `sign_event` (`id` int NOT NULL AUTO_INCREMENT,`name` varchar(50) DEFAULT NULL COMMENT '名称',`limit` int DEFAULT NULL COMMENT 'limit',`status` varchar(1) DEFAULT '1' COMMENT '状态   0：隐藏   1：显示',`address` varchar(500) DEFAULT NULL COMMENT '地址',start_time DATE,create_time DATE,PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8mb4 COMMENT='系统配置信息表';

CREATE TABLE `sign_guest` (`event_id` int NOT NULL ,`realname` varchar(50) DEFAULT NULL COMMENT '名称',`phone` varchar(11) COMMENT '手机号',`email` varchar(50) ,`sign` VARCHAR(1) DEFAULT '1' COMMENT '状态   0：隐藏   1：显示',create_time DATE,PRIMARY KEY (`event_id`,`phone`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8mb4 COMMENT='嘉宾表';

insert into  sign_guest(realname,phone,email,sign,event_id,create_time)values("tom","12344444","1111@qq.com",1,123456,now())

select * from sign_guest

from pymysql import cursors, connect# 连接数据库
conn = connect(host='192.168.56.10', user='root', password='root',db='guest', charset='utf8mb4', cursorclass=cursors.DictCursor)try:with conn.cursor() as cursors:# 创建嘉宾数据sql = 'insert into  sign_guest(realname,phone,email,sign,event_id,create_time)values("tom2","12344444","1111@qq.com",1,123456,now())'cursors.execute(sql)conn.commit()with conn.cursor() as cursor:# 查询sql = "select  *  from sign_guest where phone=%s"cursor.execute(sql, ('12344444',))res = cursor.fetchone()print(res)
finally:conn.close()

 Django 连接 mysql 

DATABASES = {'default': {'ENGINE': 'django.db.backends.sqlite3','NAME': os.path.join(BASE_DIR, 'db.sqlite3'),}
}

import pymysql
pymysql.install_as_MySQLdb()"""
如果你使用pymysql驱动的话，上面两行必须添加。
"""

E:\data\python\djaongo_prj\guest> python  manage.py migrate
Traceback (most recent call last):File "E:\data\python\djaongo_prj\guest\manage.py", line 21, in <module>main()File "E:\data\python\djaongo_prj\guest\manage.py", line 17, in mainexecute_from_command_line(sys.argv)File "D:\software\python3\anconda3\Lib\site-packages\django\core\management\__init__.py", line 442, in execute_from_command_lineutility.execute()File "D:\software\python3\anconda3\Lib\site-packages\django\core\management\__init__.py", line 436, in executeself.fetch_command(subcommand).run_from_argv(self.argv)File "D:\software\python3\anconda3\Lib\site-packages\django\core\management\base.py", line 412, in run_from_argvself.execute(*args, **cmd_options)File "D:\software\python3\anconda3\Lib\site-packages\django\core\management\base.py", line 458, in executeoutput = self.handle(*args, **options)File "D:\software\python3\anconda3\Lib\site-packages\django\core\management\base.py", line 106, in wrapperres = handle_func(*args, **kwargs)File "D:\software\python3\anconda3\Lib\site-packages\django\core\management\commands\migrate.py", line 100, in handleself.check(databases=[database])File "D:\software\python3\anconda3\Lib\site-packages\django\core\management\base.py", line 485, in checkall_issues = checks.run_checks(File "D:\software\python3\anconda3\Lib\site-packages\django\core\checks\registry.py", line 88, in run_checksnew_errors = check(app_configs=app_configs, databases=databases)File "D:\software\python3\anconda3\Lib\site-packages\django\core\checks\model_checks.py", line 36, in check_all_modelserrors.extend(model.check(**kwargs))File "D:\software\python3\anconda3\Lib\site-packages\django\db\models\base.py", line 1558, in check*cls._check_indexes(databases),File "D:\software\python3\anconda3\Lib\site-packages\django\db\models\base.py", line 2002, in _check_indexesconnection.features.supports_expression_indexesFile "D:\software\python3\anconda3\Lib\site-packages\django\utils\functional.py", line 57, in __get__res = instance.__dict__[self.name] = self.func(instance)File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\mysql\features.py", line 317, in supports_expression_indexesnot self.connection.mysql_is_mariadbFile "D:\software\python3\anconda3\Lib\site-packages\django\utils\functional.py", line 57, in __get__res = instance.__dict__[self.name] = self.func(instance)File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\mysql\base.py", line 439, in mysql_is_mariadbreturn "mariadb" in self.mysql_server_info.lower()File "D:\software\python3\anconda3\Lib\site-packages\django\utils\functional.py", line 57, in __get__res = instance.__dict__[self.name] = self.func(instance)File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\mysql\base.py", line 425, in mysql_server_inforeturn self.mysql_server_data["version"]File "D:\software\python3\anconda3\Lib\site-packages\django\utils\functional.py", line 57, in __get__res = instance.__dict__[self.name] = self.func(instance)File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\mysql\base.py", line 399, in mysql_server_datawith self.temporary_connection() as cursor:File "D:\software\python3\python310\lib\contextlib.py", line 135, in __enter__return next(self.gen)File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\base\base.py", line 705, in temporary_connectionwith self.cursor() as cursor:File "D:\software\python3\anconda3\Lib\site-packages\django\utils\asyncio.py", line 26, in innerreturn func(*args, **kwargs)File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\base\base.py", line 330, in cursorreturn self._cursor()File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\base\base.py", line 306, in _cursorself.ensure_connection()File "D:\software\python3\anconda3\Lib\site-packages\django\utils\asyncio.py", line 26, in innerreturn func(*args, **kwargs)File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\base\base.py", line 289, in ensure_connectionself.connect()File "D:\software\python3\anconda3\Lib\site-packages\django\utils\asyncio.py", line 26, in innerreturn func(*args, **kwargs)File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\base\base.py", line 272, in connectself.init_connection_state()File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\mysql\base.py", line 257, in init_connection_statesuper().init_connection_state()File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\base\base.py", line 239, in init_connection_stateself.check_database_version_supported()File "D:\software\python3\anconda3\Lib\site-packages\django\db\backends\base\base.py", line 214, in check_database_version_supportedraise NotSupportedError(
django.db.utils.NotSupportedError: MySQL 8 or later is required (found 5.7.36).E:\data\python\djaongo_prj\guest>

django.db.utils.NotSupportedError: MySQL 8 or later is required (found 5.7.36).

django.db.utils.NotSupportedError: MySQL 8 or later is required (found 5.7.2)简单快速的解决办法_疯狂的小强呀的博客-CSDN博客

这个问题是说我们的Django框架版本比较新，已经不支持MySQL老版本5.7.2了，MySQL8或者更新的版本才是我们需要的或者说匹配的。

解决方案

D:\software\python3\python310\python.exe E:/data/python/djaongo_prj/guest/manage.py runserver 127.0.0.1:8001
D:\software\python3\anconda3\Lib\site-packages\numpy\__init__.py:138: UserWarning: mkl-service package failed to import, therefore Intel(R) MKL initialization ensuring its correct out-of-the box operation under condition when Gnu OpenMP had already been loaded by Python process is not assured. Please install mkl-service package, see http://github.com/IntelPython/mkl-servicefrom . import _distributor_init
D:\software\python3\anconda3\Lib\site-packages\numpy\__init__.py:138: UserWarning: mkl-service package failed to import, therefore Intel(R) MKL initialization ensuring its correct out-of-the box operation under condition when Gnu OpenMP had already been loaded by Python process is not assured. Please install mkl-service package, see http://github.com/IntelPython/mkl-servicefrom . import _distributor_init
Performing system checks...System check identified no issues (0 silenced).You have 16 unapplied migration(s). Your project may not work properly until you apply the migrations for app(s): admin, auth, contenttypes, sessions, sign.
Run 'python manage.py migrate' to apply them.
October 02, 2023 - 21:57:38
Django version 2.1.13, using settings 'guest.settings'
Starting development server at http://127.0.0.1:8001/
Quit the server with CTRL-BREAK.

  File "D:\software\python3\anconda3\Lib\site-packages\pymysql\protocol.py", line 221, in raise_for_errorerr.raise_mysql_exception(self._data)File "D:\software\python3\anconda3\Lib\site-packages\pymysql\err.py", line 143, in raise_mysql_exceptionraise errorclass(errno, errval)
django.db.utils.OperationalError: (1050, "Table 'sign_event' already exists")E:\data\python\djaongo_prj\guest>python  manage.py migrate
Operations to perform:Apply all migrations: admin, auth, contenttypes, sessions, sign
Running migrations:Applying sign.0001_initial... OKE:\data\python\djaongo_prj\guest>

E:\data\python\djaongo_prj\guest>python manage.py createsuperuser
Username (leave blank to use 'administrator'): admin
Email address: 11111@qq.com
Password:
Password (again):
Superuser created successfully.