Django：关系映射，一对一映射OneToOneField

C:\Users\520\mysite>python manage.py startapp oto

C:\Users\520\mysite>

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'myapp.apps.MyappConfig',
    "oto",
]

# oto.models.py
from django.db import models

# Create your models here.
class Author(models.Model):
    name = models.CharField(max_length=11, verbose_name="姓名")

class Wife(models.Model):
    name = models.CharField(max_length=11, verbose_name="姓名")
    author = models.OneToOneField(Author, on_delete=models.CASCADE)
    

C:\Users\520\mysite>python manage.py makemigrations
Migrations for 'oto':
  oto\migrations\0001_initial.py
    - Create model Author
    - Create model Wife

C:\Users\520\mysite>python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, myapp, oto, sessions
Running migrations:
  Applying oto.0001_initial... OK

C:\Users\520\mysite>

Microsoft Windows [版本 10.0.19042.985]
(c) Microsoft Corporation。保留所有权利。

C:\Users\520>cd..

C:\Users>cd..

C:\>cd program files\mysql\mysql server 8.0\bin

C:\Program Files\MySQL\MySQL Server 8.0\bin>mysql -uroot -p
Enter password: ****
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 237
Server version: 8.0.25 MySQL Community Server - GPL

Copyright (c) 2000, 2021, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use mysite;
Database changed
mysql> show tables;
+----------------------------+
| Tables_in_mysite           |
+----------------------------+
| auth_group                 |
| auth_group_permissions     |
| auth_permission            |
| auth_user                  |
| auth_user_groups           |
| auth_user_user_permissions |
| author                     |
| book                       |
| django_admin_log           |
| django_content_type        |
| django_migrations          |
| django_session             |
| oto_author                 |
| oto_wife                   |
+----------------------------+
14 rows in set (0.00 sec)

mysql> desc oto_wife;
+-----------+-------------+------+-----+---------+----------------+
| Field     | Type        | Null | Key | Default | Extra          |
+-----------+-------------+------+-----+---------+----------------+
| id        | bigint      | NO   | PRI | NULL    | auto_increment |
| name      | varchar(11) | NO   |     | NULL    |                |
| author_id | bigint      | NO   | UNI | NULL    |                |
+-----------+-------------+------+-----+---------+----------------+
3 rows in set (0.02 sec)

mysql> desc oto_author;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | bigint      | NO   | PRI | NULL    | auto_increment |
| name  | varchar(11) | NO   |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+
2 rows in set (0.01 sec)

mysql>

Django模型类的名字，在数据库里是“应用名_模型类名小写”
Django模型类类属性名里的映射属性名，在数据库里是“关联模型类名_id”

C:\Users\520\mysite>python manage.py shell
Python 3.7.7 (tags/v3.7.7:d7c567b08f, Mar 10 2020, 10:41:24) [MSC v.1900 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from oto.models import *
>>> a1 = Author.objects.create(name="wang")
>>> w1 = Wife.objects.create(name="wangfuren", author=a1)
>>> a2 = Author.objects.create(name="guo")
>>> w2 = Wife.objects.create(name="guofuren", author_id=2)
>>>

mysql> select * from oto_wife;
+----+-----------+-----------+
| id | name      | author_id |
+----+-----------+-----------+
|  1 | wangfuren |         1 |
|  2 | guofuren  |         2 |
+----+-----------+-----------+
2 rows in set (0.00 sec)

mysql>

>>> a1 = Author.objects.create(name="wang")
>>> w1 = Wife.objects.create(name="wangfuren", author=a1)
>>> a2 = Author.objects.create(name="guo")
>>> w2 = Wife.objects.create(name="guofuren", author_id=2)
>>> w2
(2)>
>>> w2.name
'guofuren'
>>> w2.author.name
'guo'
>>> w1.author.name
'wang'
>>>

>>> a1 = Author.objects.create(name="wang")
>>> w1 = Wife.objects.create(name="wangfuren", author=a1)
>>> a2 = Author.objects.create(name="guo")
>>> a1
(1)>
>>> a1.wife
(1)>
>>> a1.wife.name
'wangfuren'