056.Python前端Django模型ORM多表基本操作

一 准备工作

1.1 新建一个项目

root@darren-virtual-machine:~# cd /root/PycharmProjects/

root@darren-virtual-machine:~/PycharmProjects# django-admin startproject orm_demo

root@darren-virtual-machine:~/PycharmProjects# ll

drwxr-xr-x  7 root root 4096 4月   5 20:04 mysite/
drwxr-xr-x  3 root root 4096 4月   6 13:27 orm_demo/
drwxr-xr-x  3 root root 4096 4月   5 16:27 pymysql/

root@darren-virtual-machine:~/PycharmProjects/orm_demo# python3 manage.py startapp app01

root@darren-virtual-machine:~/PycharmProjects/orm_demo# ll

drwxr-xr-x 3 root root 4096 4月   6 13:29 app01/
drwxr-xr-x 3 root root 4096 4月   6 13:28 .idea/
-rwxr-xr-x 1 root root  628 4月   6 13:27 manage.py*
drwxr-xr-x 3 root root 4096 4月   6 13:29 orm_demo/

设置setting.py

root@darren-virtual-machine:~/PycharmProjects/orm_demo# cat orm_demo/settings.py

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'app01.apps.App01Config',
]

1.2 创建一个新的数据库

root@darren-virtual-machine:~/PycharmProjects/orm_demo# mysql -uroot -p123456

mysql> create database orm_demo default charset=utf8;
Query OK, 1 row affected (0.01 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| django             |
| mysql              |
| orm_demo           |
| performance_schema |
| sys                |
+--------------------+

配置setting链接数据库

root@darren-virtual-machine:~/PycharmProjects/orm_demo# cat orm_demo/settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'orm_demo',
        'HOST': '127.0.0.1',
        'PORT': 3306,
        'USER': "root",
        'PASSWORD': "123456",
    }
}

导入__init__.py

root@darren-virtual-machine:~/PycharmProjects/orm_demo# cat orm_demo/__init__.py

import pymysql
pymysql.install_as_MySQLdb()

1.3 创建模型

root@darren-virtual-machine:~/PycharmProjects/orm_demo# cat app01/models.py 

from django.db import models

# Create your models here.
class Book(models.Model):
    title = models.CharField(max_length=32)
    price = models.DecimalField(max_digits=5, decimal_places=2)
    pub_date = models.DateField()
    publish = models.ForeignKey("Publish", on_delete=models.CASCADE)
    authors = models.ManyToManyField("Author")


class Publish(models.Model):
    name = models.CharField(max_length=32)
    city = models.CharField(max_length=64)
    email = models.EmailField()


class Author(models.Model):
    name = models.CharField(max_length=32)
    age = models.SmallIntegerField()
    au_detail = models.OneToOneField("AuthorDetail", on_delete=models.CASCADE)


class AuthorDetail(models.Model):
    gender_choices = (
        (0, "女"),
        (1, "男"),
        (2, "保密"),
    )
    gender = models.SmallIntegerField(choices=gender_choices)
    tel = models.CharField(max_length=32)
    addr = models.CharField(max_length=64)
    birthday = models.DateField()

1.4 执行数据库迁移操作

root@darren-virtual-machine:~/PycharmProjects/orm_demo# python3 manage.py makemigrations

Migrations for 'app01':
  app01/migrations/0001_initial.py
    - Create model Author
    - Create model AuthorDetail
    - Create model Publish
    - Create model Book
    - Add field au_detail to author

root@darren-virtual-machine:~/PycharmProjects/orm_demo# cat app01/migrations/0001_initial.py

# Generated by Django 3.0.5 on 2020-04-06 07:10

from django.db import migrations, models
import django.db.models.deletion


class Migration(migrations.Migration):

    initial = True

    dependencies = [
    ]

    operations = [
        migrations.CreateModel(
            name='Author',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('name', models.CharField(max_length=32)),
                ('age', models.SmallIntegerField()),
            ],
        ),
        migrations.CreateModel(
            name='AuthorDetail',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('gender', models.SmallIntegerField(choices=[(0, '女'), (1, '男'), (2, '保密')])),
                ('tel', models.CharField(max_length=32)),
                ('addr', models.CharField(max_length=64)),
                ('birthday', models.DateField()),
            ],
        ),
        migrations.CreateModel(
            name='Publish',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('name', models.CharField(max_length=32)),
                ('city', models.CharField(max_length=64)),
                ('email', models.EmailField(max_length=254)),
            ],
        ),
        migrations.CreateModel(
            name='Book',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('title', models.CharField(max_length=32)),
                ('price', models.DecimalField(decimal_places=2, max_digits=5)),
                ('pub_date', models.DateField()),
                ('authors', models.ManyToManyField(to='app01.Author')),
                ('publish', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='app01.Publish')),
            ],
        ),
        migrations.AddField(
            model_name='author',
            name='au_detail',
            field=models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, to='app01.AuthorDetail'),
        ),
    ]

root@darren-virtual-machine:~/PycharmProjects/orm_demo# python3 manage.py migrate

Operations to perform:
  Apply all migrations: admin, app01, 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 app01.0001_initial... 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

1.5 查看数据库数据

mysql> use orm_demo
mysql> show tables;
+----------------------------+
| Tables_in_orm_demo         |
+----------------------------+
| app01_author               |
| app01_authordetail         |
| app01_book                 |
| app01_book_authors         |
| app01_publish              |
| auth_group                 |
| auth_group_permissions     |
| auth_permission            |
| auth_user                  |
| auth_user_groups           |
| auth_user_user_permissions |
| django_admin_log           |
| django_content_type        |
| django_migrations          |
| django_session             |
+----------------------------+

四个模型，但是创建了五张表，其中自己创建的表的信息如下

mysql> desc app01_book_authors;

+-----------+---------+------+-----+---------+----------------+
| Field     | Type    | Null | Key | Default | Extra          |
+-----------+---------+------+-----+---------+----------------+
| id        | int(11) | NO   | PRI | NULL    | auto_increment |
| book_id   | int(11) | NO   | MUL | NULL    |                |
| author_id | int(11) | NO   | MUL | NULL    |                |
+-----------+---------+------+-----+---------+----------------+

查看数据库表的信息

mysql> desc app01_author
    -> ;
+--------------+-------------+------+-----+---------+----------------+
| Field        | Type        | Null | Key | Default | Extra          |
+--------------+-------------+------+-----+---------+----------------+
| id           | int(11)     | NO   | PRI | NULL    | auto_increment |
| name         | varchar(32) | NO   |     | NULL    |                |
| age          | smallint(6) | NO   |     | NULL    |                |
| au_detail_id | int(11)     | NO   | UNI | NULL    |                |
+--------------+-------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

mysql> desc app01_authordetail
    -> ;
+----------+-------------+------+-----+---------+----------------+
| Field    | Type        | Null | Key | Default | Extra          |
+----------+-------------+------+-----+---------+----------------+
| id       | int(11)     | NO   | PRI | NULL    | auto_increment |
| gender   | smallint(6) | NO   |     | NULL    |                |
| tel      | varchar(32) | NO   |     | NULL    |                |
| addr     | varchar(64) | NO   |     | NULL    |                |
| birthday | date        | NO   |     | NULL    |                |
+----------+-------------+------+-----+---------+----------------+
5 rows in set (0.01 sec)

mysql> desc app01_book;
+------------+--------------+------+-----+---------+----------------+
| Field      | Type         | Null | Key | Default | Extra          |
+------------+--------------+------+-----+---------+----------------+
| id         | int(11)      | NO   | PRI | NULL    | auto_increment |
| title      | varchar(32)  | NO   |     | NULL    |                |
| price      | decimal(5,2) | NO   |     | NULL    |                |
| pub_date   | date         | NO   |     | NULL    |                |
| publish_id | int(11)      | NO   | MUL | NULL    |                |
+------------+--------------+------+-----+---------+----------------+
5 rows in set (0.00 sec)

mysql> desc app01_book_authors;
+-----------+---------+------+-----+---------+----------------+
| Field     | Type    | Null | Key | Default | Extra          |
+-----------+---------+------+-----+---------+----------------+
| id        | int(11) | NO   | PRI | NULL    | auto_increment |
| book_id   | int(11) | NO   | MUL | NULL    |                |
| author_id | int(11) | NO   | MUL | NULL    |                |
+-----------+---------+------+-----+---------+----------------+
3 rows in set (0.00 sec)

mysql> desc app01_book_publish;
ERROR 1146 (42S02): Table 'orm_demo.app01_book_publish' doesn't exist
mysql> desc app01_book_publish;er
ERROR 1146 (42S02): Table 'orm_demo.app01_book_publish' doesn't exist
    -> ^C

^C
mysql> desc app01_book_publisher;
ERROR 1146 (42S02): Table 'orm_demo.app01_book_publisher' doesn't exist
mysql> desc app01_publisher;
ERROR 1146 (42S02): Table 'orm_demo.app01_publisher' doesn't exist
mysql> desc app01_publish;
+-------+--------------+------+-----+---------+----------------+
| Field | Type         | Null | Key | Default | Extra          |
+-------+--------------+------+-----+---------+----------------+
| id    | int(11)      | NO   | PRI | NULL    | auto_increment |
| name  | varchar(32)  | NO   |     | NULL    |                |
| city  | varchar(64)  | NO   |     | NULL    |                |
| email | varchar(254) | NO   |     | NULL    |                |
+-------+--------------+------+-----+---------+----------------+

1.6 向数据库中插入数据

mysql> insert into app01_publish(name,city,email) 
    -> values
    -> ("华山出版社", "华山", "hs@163.com"), 
    -> ("明教出版社", "黑木崖", "mj@163.com")
    -> ;

查看数据

mysql> select * from app01_publish;
+----+-----------------+-----------+------------+
| id | name            | city      | email      |
+----+-----------------+-----------+------------+
|  1 | 华山出版社      | 华山      | hs@163.com |
|  2 | 明教出版社      | 黑木崖    | mj@163.com |
+----+-----------------+-----------+------------+

app01_authordetail表

mysql> insert into app01_authordetail(gender,tel,addr,birthday) 
    -> values
    -> (1,13432335433,"华山","1994-5-23"),
    -> (1,13943454554,"黑木崖","1961-8-13"),
    -> (0,13878934322,"黑木崖","1996-5-20") ;
Query OK, 3 rows affected (0.00 sec)

查看数据

mysql> select * from app01_authordetail;
+----+--------+-------------+-----------+------------+
| id | gender | tel         | addr      | birthday   |
+----+--------+-------------+-----------+------------+
|  1 |      1 | 13432335433 | 华山      | 1994-05-23 |
|  2 |      1 | 13943454554 | 黑木崖    | 1961-08-13 |
|  3 |      0 | 13878934322 | 黑木崖    | 1996-05-20 |
+----+--------+-------------+-----------+------------+

必许先添加这一步，再插入app01_author，否则报错如下

ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails (`orm_demo`.`app01_author`, CONSTRAINT `app01_author_au_detail_id_440c948c_fk_app01_authordetail_id` FOREIGN KEY (`au_detail_id`) REFERENCES `app01_authordetail` (`id`))

插入app01_author表

mysql> insert into app01_author(name,age,au_detail_id) values ("令狐冲",25,1), ("任我行",58,2), ("任盈盈",23,3) ;

查看

mysql> select * from app01_author;
+----+-----------+-----+--------------+
| id | name      | age | au_detail_id |
+----+-----------+-----+--------------+
|  7 | 令狐冲    |  25 |            1 |
|  8 | 任我行    |  58 |            2 |
|  9 | 任盈盈    |  23 |            3 |
+----+-----------+-----+--------------+

各表关系

二 对数据库数据进行操作

2.1 插入数据

2.1.1 一对多

出版社和书是一对多关系

设计路由

root@darren-virtual-machine:~/PycharmProjects/orm_demo# cat orm_demo/urls.py

from django.contrib import admin
from django.urls import path
from app01 import views
urlpatterns = [
    path('admin/', admin.site.urls),
    path('add_book',views.add_book),
]

创建一个html模板

root@darren-virtual-machine:~/PycharmProjects/orm_demo# mkdir templates

root@darren-virtual-machine:~/PycharmProjects/orm_demo# vim orm_demo/settings.py 

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [os.path.join(BASE_DIR,"templates")],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

root@darren-virtual-machine:~/PycharmProjects/orm_demo# vim templates/add_book.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <h3>新增书籍</h3>
    <form action="" method="post">
    {% csrf_token %}
    <p>书名：<input type="text" name="title"></p>
    <p>出版社：<input type="text" name="publisher"></p>
    <p>价格：<input type="text" name="price"></p>
    <p>出版时间：<input type="text" name="pub_date"></p>
    <input type="submit">
</form>
</body>
</html>

视图文件

root@darren-virtual-machine:~/PycharmProjects/orm_demo# vim app01/views.py 

from django.shortcuts import render,HttpResponse
from app01 import models
# Create your views here.
def add_book(request):
    if request.method == "GET":
        return render(request,"add_book.html")
    else:
        #获取数据
        title = request.POST.get("title")
        publish = request.POST.get("publish")
        price = request.POST.get("price")
        pub_date = request.POST.get("pub_date")
        #方式一，通过传对象的方式，首先获取对象
        pub_obj = models.Publish.objects.filter(name=publish).first()
        book_obj = models.Book.objects.create(title=title,price=price,pub_date=pub_date,publish=pub_obj)return HttpResponse("新增成功")

访问http://127.0.0.1:8000/add_book/并添加数据

 点击提交，查看数据库

使用方式二

root@darren-virtual-machine:~/PycharmProjects/orm_demo# vim app01/views.py

from django.shortcuts import render,HttpResponse
from app01 import models
# Create your views here.
def add_book(request):
    if request.method == "GET":
        return render(request,"add_book.html")
    else:
        #获取数据
        title = request.POST.get("title")
        publish = request.POST.get("publish")
        price = request.POST.get("price")
        pub_date = request.POST.get("pub_date")
        #方式二，通过id的形式，在publish_id后也可以直接跟数字
        pub_obj = models.Publish.objects.filter(name=publish).first()
        books = models.Book.objects.create(title=title, price=price, pub_date=pub_date, publish_id=pub_obj.pk)
    return HttpResponse("新增成功")

访问http://127.0.0.1:8000/add_book/并添加数据

点击提交

 

查看数据库

2.1.2 多对多

视图文件

root@darren-virtual-machine:~/PycharmProjects/orm_demo# vim app01/views.py

from django.shortcuts import render,HttpResponse
from app01 import models
# Create your views here.
def add_book(request):
    if request.method == "GET":
        return render(request,"add_book.html")
    else:
        #获取数据
        title = request.POST.get("title")
        publish = request.POST.get("publish")
        price = request.POST.get("price")
        pub_date = request.POST.get("pub_date")
        #方式一，通过传对象的方式，首先获取对象
        #pub_obj = models.Publish.objects.filter(name=publish).first()
        #book_obj = models.Book.objects.create(title=title,price=price,pub_date=pub_date,publish=pub_obj)
        #books = models.Book.objects.create(title=title, price=price, pub_date=pub_date, publish_id=pub_obj.pk)
        #多对多，方式一
        book = models.Book.objects.filter(title="独孤九剑").first()
        ling = models.Author.objects.filter(name="令狐冲").first()
        ying = models.Author.objects.filter(name="任盈盈").first()
        book.authors.add(ling, ying)
    return HttpResponse("新增成功")

访问http://127.0.0.1:8000/add_book/，直接提交

查看数据库

方式二

root@darren-virtual-machine:~/PycharmProjects/orm_demo# vim app01/views.py

from django.shortcuts import render,HttpResponse
from app01 import models
# Create your views here.
def add_book(request):
    if request.method == "GET":
        return render(request,"add_book.html")
    else:
        #获取数据
        title = request.POST.get("title")
        publish = request.POST.get("publish")
        price = request.POST.get("price")
        pub_date = request.POST.get("pub_date")
        #方式一，通过传对象的方式，首先获取对象
        #pub_obj = models.Publish.objects.filter(name=publish).first()
        #book_obj = models.Book.objects.create(title=title,price=price,pub_date=pub_date,publish=pub_obj)
        #books = models.Book.objects.create(title=title, price=price, pub_date=pub_date, publish_id=pub_obj.pk)
        #多对多，方式一
        #book = models.Book.objects.filter(title="独孤九剑").first()
        #ling = models.Author.objects.filter(name="令狐冲").first()
        #ying = models.Author.objects.filter(name="任盈盈").first()
        #book.authors.add(ling, ying)
        #方式二
        book = models.Book.objects.filter(title="独孤九剑").first()
        ling = models.Author.objects.filter(name='令狐冲').first()
        ying = models.Author.objects.filter(name='任我行').first()
        book.authors.add(ling.pk, ying.pk)
    return HttpResponse("新增成功")

访问http://127.0.0.1:8000/add_book/，直接提交

查看数据库

  

2.2 删除数据

使用clear，先查出一个对象，然后移除相应关系

views  视图文件

通过作者删除与书籍的关系

from django.shortcuts import render,HttpResponse
from app01 import models
# Create your views here.
def add_book(request):
    if request.method == "GET":
        return render(request,"add_book.html")
    else:
        author_obj = models.Author.objects.filter(au_detail_id=1).first()
        print(author_obj)
        author_obj.book_set.clear()
    return HttpResponse("success")

访问http://127.0.0.1:8000/add_book/，直接提交

查看数据库

通过出版社删除书籍，使用remove方法

from django.shortcuts import render,HttpResponse
from app01 import models
# Create your views here.
def add_book(request):
    if request.method == "GET":
        return render(request,"add_book.html")
    else:
        pub_obj = models.Publish.objects.get(pk=1)
        book_obj = models.Book.objects.get(pk=1)
        pub_obj.book_set.remove(book_obj)
    return HttpResponse("新增成功")

然后

访问http://127.0.0.1:8000/add_book/，直接提交

 

没有remove方法，必须在model设定，可以允许null值，才会有remove方法

root@darren-virtual-machine:~/PycharmProjects/orm_demo# vim app01/models.py

class Book(models.Model):
    title = models.CharField(max_length=32)
    price = models.DecimalField(max_digits=5, decimal_places=2)
    pub_date = models.DateField()
    publish = models.ForeignKey("Publish", on_delete=models.CASCADE,null=True)
    authors = models.ManyToManyField("Author")

再次访问

需要重新执行迁移数据库操作

root@darren-virtual-machine:~/PycharmProjects/orm_demo# python3 manage.py makemigrations 

root@darren-virtual-machine:~/PycharmProjects/orm_demo# python3 manage.py migrate

访问http://127.0.0.1:8000/add_book/，直接提交

2.3 修改数据

set()方法

先清空，在设置，编辑书籍时即可用到。

book = models.Book.objects.filter(title="独孤九剑").first()
book.authors.set([1, 3])　

基本操作结束