[Python知识库]第一章 Django快速入门

1. 环境搭建

参考：https://docs.djangoproject.com/zh-hans/4.1/faq/install/#faq-python-version-support

安装django正式发布版

python -m pip install Django

查看django版本

python -m django --version

创建django项目

django-admin startproject django_learn

项目结构

.
├── django_learn
│   ├── asgi.py
│   ├── __init__.py
│   ├── settings.py
│   ├── urls.py
│   └── wsgi.py
└── manage.py

• asgi.py 项目的运行在（ ASGI 兼容的） Web 服务器上的入口 如何使用 ASGI 来部署
• wsgi.py 项目的运行在 （WSGI 兼容的）Web服务器上的入口 如何使用 WSGI 进行部署
• manage.py 管理django项目命令 命令详情
• url.py url路径声明
• settings.py 配置项目数据库等 详情

项目运行到0.0.0.0:8080

python manage.py runserver 0:8080

2. 快速开发

在manage.py同级目录创建app

python manage.py startapp myapp

settings.py注册app

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

settings.py配置允许访问的地址

ALLOWED_HOSTS = ['*']

views.py

from django.http import HttpResponse


def index(request):
    return HttpResponse('hello world')

myapp目录下新建urls.py

from django.urls import path
from . import views

urlpatterns = [
    path('', views.index, name='index')
]

django_learn/urls.py 新增app目录下的urls.py

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('myapp/', include('myapp.urls'))
]

启动项目，访问 http://127.0.0.1:8080/myapp/

urlpatterns使用方式

3. 数据库使用

以mysql为例（参考：https://docs.djangoproject.com/zh-hans/4.1/ref/databases/#mysql-notes）

安装mysql相关依赖（以ubuntu为例，其他环境参考：https://pypi.org/project/mysqlclient）

sudo apt-get install python3-dev default-libmysqlclient-dev build-essential

pip install mysqlclient

在settings.py配置mysql数据库

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

ENGINE配置其他数据库

    'django.db.backends.postgresql'
    'django.db.backends.sqlite3'
    'django.db.backends.oracle'

自定义表对象myapp/models.py

from django.db import models


# Create your models here.


class Subject(models.Model):
    """
    科目
    """
    name = models.CharField(max_length=50, verbose_name='科目名')
    create_time = models.DateTimeField(verbose_name='创建时间')
    update_time = models.DateTimeField(blank=True, null=True, verbose_name='更新时间')
    is_delete = models.BooleanField(default=False, verbose_name='逻辑删除')

    class Meta:
        db_table = 'tb_subject'


class Student(models.Model):
    """
    学生
    """
    name = models.CharField(max_length=50, verbose_name='学生名')
    age = models.IntegerField(verbose_name='年龄')
    create_time = models.DateTimeField(verbose_name='创建时间')
    update_time = models.DateTimeField(blank=True, null=True, verbose_name='更新时间')
    is_delete = models.BooleanField(default=False, verbose_name='逻辑删除')
    sid = models.ForeignKey(Subject, on_delete=models.DO_NOTHING, db_column='sid', verbose_name='科目id')

    class Meta:
        db_table = 'tb_student'

• db_table：配置表名
• on_delete：配置外键关联删除
• verbose_name：字段在后台系统显示的名称

执行迁移

python manage.py makemigrations myapp

修改的内容被保存到myapp/migrations/0001_initial.py

查看对应的sql语句

python manage.py sqlmigrate myapp 0001

--
-- Create model Subject
--
CREATE TABLE `tb_subject` (`id` bigint AUTO_INCREMENT NOT NULL PRIMARY KEY, `name` varchar(50) NOT NULL, `create_time` datetime(6) NOT NULL, `update_time` datetime(6) NULL, `is_delete` bool NOT NULL);
--
-- Create model Student
--
CREATE TABLE `tb_student` (`id` bigint AUTO_INCREMENT NOT NULL PRIMARY KEY, `name` varchar(50) NOT NULL, `age` integer NOT NULL, `create_time` datetime(6) NOT NULL, `update_time` datetime(6) NULL, `is_delete` bool NOT NULL, `sid` bigint NOT NULL);
ALTER TABLE `tb_student` ADD CONSTRAINT `tb_student_sid_c066e3db_fk_tb_subject_id` FOREIGN KEY (`sid`) REFERENCES `tb_subject` (`id`);

确认无误后迁移到数据库

pyhton manage.py migrate

view.py

def get_subject(request):
    subjects = Subject.objects.all()
    data = [{'name': s.name} for s in subjects]
    return HttpResponse(data)


def set_subject(request):
    name = request.GET['name']
    subjects = Subject()
    subjects.name = name
    subjects.create_time = datetime.datetime.now()
    subjects.save()
    return HttpResponse('ok')

• request.GET：获取请求参数
• Subject.objects.all()：查询tb_subject表所有数据

url.py

    path('stu/get_subject', views.get_subject, name='get_subject'),
    path('stu/set_subject', views.set_subject, name='set_subject'),

访问浏览器

http://0.0.0.0:8080/myapp/stu/set_subject?name=语文
http://0.0.0.0:8080/myapp/stu/set_subject?name=数学

http://0.0.0.0:8080/myapp/stu/get_subject

4. 后台管理系统

创建超级用户

python manage.py createsuperuser

注册subject对象
myapp/admin.py

from django.contrib import admin

# Register your models here.
from myapp.models import Subject

admin.site.register(Subject)