Django入门开发之数据模型01

1. Django安装

[root@HappyLau ~]# pip install django==1.8.

2. 创建项目

[root@HappyLau html]# django-admin startproject demo

查看项目的结构：
[root@HappyLau html]# tree demo/
demo/
├── demo
│   ├── __init__.py
│   ├── __init__.pyc
│   ├── settings.py
│   ├── settings.pyc
│   ├── urls.py
│   └── wsgi.py
└── manage.py

1 directory, 7 files

demo目录文件说明：
__init__.py        代表是一个包
settings.py        配置文件，环境设定
urls.py               urls地址映射关系
wsgi.py             wsgi.py设定，django是遵循WSGI协议的框架

启动django web服务器，运行python manage.py runserver,然后django会默认运行在本机的8000/tcp端口，然后可以通过浏览器访问。如下图：

如需要中文，可以修改django支持中文环境，编辑settings.py文件，设定内容如下：

LANGUAGE_CODE = 'zh-hans'
TIME_ZONE = 'Asia/Shanghai'

3. 配置数据库

　　Django默认采用sqllite3数据库作为数据持久存储，实际工作中一般使用MySQL作为结构化数据存储，在python2中使用python-MySQL作为python和MySQL数据库交互的API，而python3中使用pymysql，且不支持python-MySQL，所以以pymysql作为主体使用，需要在项目/应用的__init__.py文件中定义使用如下：

[root@HappyLau demo]# cat demo/__init__.py
import pymysql
pymysql.install_as_MySQLdb()

1. 安装MySQL数据库和pymysql模块

root@HappyLau demo]# yum install mariadb mariadb-server python2-PyMySQL -y

修改MariaDB的默认字符集,修改server端
[root@HappyLau demo]# vim /etc/my.cnf.d/server.cnf 
[server]
character-set-server=utf8

# this is only for the mysqld standalone daemon
[mysqld]
character-set-server=utf8

修改client端：
[root@HappyLau demo]# vim /etc/my.cnf.d/client.cnf
[client]
default-character-set=utf8

启动数据库：
[root@HappyLau demo]# systemctl restart mariadb
[root@HappyLau demo]# systemctl enable mariadb

2. 数据库环境准备

MariaDB [(none)]> create database book;
Query OK, 1 row affected (0.01 sec)
MariaDB [(none)]>
MariaDB [(none)]> grant all privileges on book.* to 'bookadmin'@'localhost' identified by 'bookpassword';
Query OK, 0 rows affected (0.04 sec)

MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.02 sec)

3. 配置Django数据库连接，修改settings.py文件，找到DATABASES行，修改内容如下:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'HOST': 'localhost',
        'PORT': 3306,
        'USER': 'bookadmin',
        'PASSWORD': 'bookpassword',
        'NAME': 'book'
    }
}

4.  创建和管理应用

1. 创建应用

[root@HappyLau demo]# django-admin startapp book

查看应用目录结构：
[root@HappyLau demo]# tree book/
book/
├── admin.py
├── __init__.py
├── migrations
│   └── __init__.py
├── models.py
├── tests.py
└── views.py

1 directory, 6 files

2. 将应用注册到django中，修改项目的settings.py文件，找到INSTALLED_APPS行，将book应用添加到其中，如下：

INSTALLED_APPS = (
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'book'
)

4. 编写应用模型

1. 定义模型的类，在每个应用包目录下的models.py文件中定义，如book应用的的book/models.py文件，定义两个模型：书本和英雄模型，其中书本作为英雄的外键而存在，如果有多个应用则在各自的应用中定义模型即可，定义如下：

[root@HappyLau demo]# cat book/models.py
#_*_ coding:utf8 _*_

from django.db import models

class Book(models.Model):
    '''
    @models.Model,定义Book数据库models类
    '''
    book_name = models.CharField(max_length=128)
    author_name = models.CharField(max_length=128)
    publish_date = models.DateTimeField()

    def __str__(self):
        '''格式化输出'''
        return self.book_name,self.author_name,self.publish_date

class Hero(models.Model):
    '''
    @models.Model，定义超人Hero数据库models类
    '''
    hero_name = models.CharField(max_length=128)
    hero_sex = models.BooleanField()
    hero_content = models.CharField(max_length=1024)
    hero_book = models.ForeignKey(Book)

    def __str__(self):
        '''格式化输出'''
        return self.hero_name,self.hero_sex,self.hero_content,self.hero_book

2. 生成模型所需的表

[root@HappyLau demo]# python manage.py  makemigrations
Migrations for 'book':
  0001_initial.py:
    - Create model Book
    - Create model Hero

[root@HappyLau demo]# python manage.py migrate
Operations to perform:
  Synchronize unmigrated apps: staticfiles, messages
  Apply all migrations: admin, contenttypes, book, auth, sessions
Synchronizing apps without migrations:
  Creating tables...
    Running deferred SQL...
  Installing custom SQL...
Running migrations:
  Rendering model states... DONE
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.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 book.0001_initial... OK
  Applying sessions.0001_initial... OK

3. 查看模型的表格，执行migrate之后，在应用的migrations目录下生成创建SQL语句的文件，如下为目录的结构，并查看文件内容，如下：

[root@HappyLau demo]# tree
.
├── book
│   ├── admin.py
│   ├── admin.pyc
│   ├── __init__.py
│   ├── __init__.pyc
│   ├── migrations
│   │   ├── 0001_initial.py     #新增的创建SQL语句的文件
│   │   ├── 0001_initial.pyc
│   │   ├── __init__.py
│   │   └── __init__.pyc
│   ├── models.py
│   ├── models.pyc
│   ├── tests.py
│   └── views.py
├── demo
│   ├── __init__.py
│   ├── __init__.pyc
│   ├── settings.py
│   ├── settings.pyc
│   ├── urls.py
│   └── wsgi.py
└── manage.py

查看 0001_initial.py文件内容，如下：
[root@HappyLau demo]# cat book/migrations/0001_initial.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import models, migrations

class Migration(migrations.Migration):

    dependencies = [
    ]

    operations = [
        migrations.CreateModel(
            name='Book',
            fields=[
                ('id', models.AutoField(verbose_name='ID', serialize=False, auto_created=True, primary_key=True)),
                ('book_name', models.CharField(max_length=128)),
                ('author_name', models.CharField(max_length=128)),
                ('publish_date', models.DateTimeField()),
            ],
        ),
        migrations.CreateModel(
            name='Hero',
            fields=[
                ('id', models.AutoField(verbose_name='ID', serialize=False, auto_created=True, primary_key=True)),
                ('hero_name', models.CharField(max_length=128)),
                ('hero_sex', models.BooleanField()),
                ('hero_content', models.CharField(max_length=1024)),
                ('hero_book', models.ForeignKey(to='book.Book')),
            ],
        ),
    ]

通过上面的文件可以发现，通过models类创建数据模型的时候会在数据库中自动生成id字段，该id字段是主键primary_key,且是自增auto_created。如下通过查看数据库的表结构，如下：

MariaDB [book]> show create table book_book ;
+-----------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table     | Create Table                                                                                                                                                                                                                                 |
+-----------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| book_book | CREATE TABLE `book_book` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `book_name` varchar(128) NOT NULL,
  `author_name` varchar(128) NOT NULL,
  `publish_date` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-----------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

MariaDB [book]> show create table book_hero ;+-----------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table     | Create Table                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+-----------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| book_hero | CREATE TABLE `book_hero` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `hero_name` varchar(128) NOT NULL,
  `hero_sex` tinyint(1) NOT NULL,
  `hero_content` varchar(1024) NOT NULL,
  `hero_book_id` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `book_hero_hero_book_id_766a63d04ebcda8c_fk_book_book_id` (`hero_book_id`),
  CONSTRAINT `book_hero_hero_book_id_766a63d04ebcda8c_fk_book_book_id` FOREIGN KEY (`hero_book_id`) REFERENCES `book_book` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-----------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

4. 使用django shell测试数据模型，django的manage.py提供一个shell工具和数据模型交互的接口，可以实现直接与数据库交互，如下：

[root@HappyLau demo]# python manage.py  shell
Python 2.7.5 (default, Aug  4 2017, 00:39:18)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
#插入数据（实际执行了INSERT语句）
>>> from book.models import Book
>>> from book.models import Hero
>>> b = Book()
>>> b.book_name = "天龙十八部"
>>> b.author = "金庸"
>>> b.publish_date = "2018-03-17"
>>> b.save()

>>> b1 = Book()
>>> b1.book_name = "射雕英雄传"
>>> b1.author = "金庸"
>>> b1.publish_date = "2018-03-17"
>>> b1.save()

外键数据插入：
>>> h = Hero()
>>> h.hero_name = "乔峰"
>>> h.hero_sex = "男"
>>> h.hero_content = "乔峰是一个大英雄，拥有盖世武功，如降龙十八掌，擒龙手等。"
>>> h.hero_book = b
>>> b.save()

>>> h1 = Hero()
>>> h1.hero_name = "郭靖"
>>> h1.hero_sex = "男"
>>> h1.hero_content = "郭靖是个傻大个，但武功高强，肯学，努力!"
>>> h1.hero_book = b1
>>> h1.save()

查询数据所有数据（实际执行了SELCT语句）：
>>> Book.objects.all()
[<Book: 天龙十八部>, <Book: 射雕英雄传>]
>>> Hero.objects.all()
[<Hero: 郭靖>, <Hero: 乔峰>]

根据条件查询数据，如根据主键查询(pk是primary_key)
>>> Book.objects.get(pk=1)
<Book: 天龙十八部>
>>> Book.objects.get(book_name="射雕英雄传")
<Book: 射雕英雄传>

更新数据(实际是执行了UPDATE语句)：
>>> book = Book.objects.get(pk=1)
>>> from datetime import datetime
>>> book.publish_date
datetime.datetime(2018, 3, 17, 0, 0, tzinfo=<UTC>)
>>> book.publish_date = datetime(year=1997,month=1,day=1)
>>> book.save()
/usr/lib64/python2.7/site-packages/django/db/models/fields/__init__.py:1474: RuntimeWarning: DateTimeField Book.publish_date received a naive datetime (1997-01-01 00:00:00) while time zone support is active.
  RuntimeWarning)

>>> book.publish_date
datetime.datetime(1997, 1, 1, 0, 0)

删除数据（实际执行了DELETE语句）：
>>> hero = Hero.objects.get(hero_name='郭靖')
>>> hero.delete()
>>> Hero.objects.all()
[<Hero: 乔峰>]
>>> hero.save()

最后查看数据库中的内容：
MariaDB [book]> select * from book_book;
+----+-----------------+-------------+---------------------+
| id | book_name       | author_name | publish_date        |
+----+-----------------+-------------+---------------------+
|  1 | 天龙十八部      |             | 1997-01-01 00:00:00 |
|  2 | 射雕英雄传      |             | 2018-03-17 00:00:00 |
+----+-----------------+-------------+---------------------+
2 rows in set (0.00 sec)

MariaDB [book]> select * from book_hero;
+----+-----------+----------+--------------------------------------------------------------------------------------+--------------+
| id | hero_name | hero_sex | hero_content                                                                         | hero_book_id |
+----+-----------+----------+--------------------------------------------------------------------------------------+--------------+
|  3 | 乔峰      |        1 | 乔峰是一个大英雄，拥有盖世武功，如降龙十八掌，擒龙手等。                             |            1 |
|  4 | 郭靖      |        1 | 郭靖是个傻大个，但武功高强，肯学，努力!                                              |            2 |
+----+-----------+----------+--------------------------------------------------------------------------------------+--------------+
2 rows in set (0.00 sec)

5.  后台数据管理

web应用中，通过web站点将数据展现给用户，这些所展示的数据最终存储在后台数据中，即需要通过一个后台管理来实现用户数据的添加/删除等操作，django默认提供了一个admin的管理后台，并提供了相关的用户管理机制，可以通过createsuperuser超级管理员账户，也可以将用户所属的应用添加到后台中管理，如下：

1. 创建管理用户，创建完管理用户之后可以通过访问http://localhost/admin页面访问，输入创建用户的用户名和密码，即可登陆。

[root@HappyLau demo]# python manage.py  createsuperuser
Username (leave blank to use 'root'): happylau
Email address: happylau@cnblogs.com
Password:
Password (again):
Superuser created successfully.

2. 注册应用到后台，即通过刚所创建的两个模型：Book模型和Hero模型通过后台的方式管理，由于设计到中文输入，所以需要通过sys.setdefaultencoding('utf8')的方法来设定字符编码，代码如下：

[root@HappyLau demo]# cat book/admin.py
import sys
reload(sys)
sys.setdefaultencoding('utf8')

from django.contrib import admin
from book.models import Book
from book.models import Hero

admin.site.register(Book)
admin.site.register(Hero)

通过访问http://localhost/admin登陆后的页面如下，可以正常的添加/删除/查询/修改数据内容：

添加书信息：

添加英雄：

6. 自定义管理页面

　　默认时候django只现实models中类的信息，可以通过django中的ModelAdmin类来自定义数据的展现，其中list_display列表可以定义需要显示的字段内容，以如下代码为例：

[root@HappyLau demo]# cat book/admin.py
#_*_ coding:utf8 _*_

import sys
reload(sys)
sys.setdefaultencoding('utf8')

from django.contrib import admin
from book.models import Book
from book.models import Hero

class BookAdmin(admin.ModelAdmin):
    '''
    定义Book管理需要显示的内容
    '''
    list_display = ['id','book_name','author_name','publish_date']

class HeroAdmin(admin.ModelAdmin):
    '''
    定义Hero管理需要现实的内容
    '''
    list_display = ['id','hero_name','hero_sex','hero_content','hero_book']

admin.site.register(Book,BookAdmin)
admin.site.register(Hero,HeroAdmin)

修改完成后，django页面的关于Hero内容显示如下，显示内容日常不错，哈哈！此外，在这里还支持字段的排序，只需要点击字段中的内容即可实现排序。

管理类中的其他功能：

1. list_display　　用于显示列表的内容，作为一个列表而使用，如list_display = ['id','book_name','author_name','publish_date']

2. list_filter　　　用于在右测显示分组内容,如list_filter = ['book_name']

3. search_fields  用于上面的关键字查询，支持模糊查询，如search_fields = ['id','book_name','author_name','publish_date']

4. list_per_page  用于设置分页，每页所容纳的条目，如list_per_page = 5

如下实现代码:

[root@HappyLau demo]# cat book/admin.py
#_*_ coding:utf8 _*_

import sys
reload(sys)
sys.setdefaultencoding('utf8')

from django.contrib import admin
from book.models import Book
from book.models import Hero

class BookAdmin(admin.ModelAdmin):
    '''
    定义Book管理需要显示的内容
    '''
    list_display = ['id','book_name','author_name','publish_date']
    list_filter = ['book_name']
    search_fields = ['id','book_name','author_name','publish_date']
    list_per_page = 5 

class HeroAdmin(admin.ModelAdmin):
    '''
    定义Hero管理需要现实的内容
    '''
    list_display = ['id','hero_name','hero_sex','hero_content','hero_book']
    search_fields = ['id','hero_name','hero_sex','hero_content','hero_book']
    list_filter = ['hero_name']
    list_per_page = 5 

admin.site.register(Book,BookAdmin)
admin.site.register(Hero,HeroAdmin)

通过上面的代码实现的功能如图：

仔细观察上如，list_display实现表格中的数据内容，list_filter实现右边的分组内容，search_fields实现上部的搜索功能，list_per_page显示每页显示内容。

7. 内嵌页的实现

　　如果希望在一个类中包含嵌套另外一个Class，可以采用嵌套的方式来实现，可以基于两种方式实现：admin.StackedInline和admin.TabularInline,如下为测试代码：

[root@HappyLau demo]# cat book/admin.py
#_*_ coding:utf8 _*_

import sys
reload(sys)
sys.setdefaultencoding('utf8')

from django.contrib import admin
from book.models import Book
from book.models import Hero

#class HeroInline(admin.StackedInline):
class HeroInline(admin.TabularInline):
    '''
    Hero类的内嵌页类
    '''
    model = Hero
    extra = 2

class BookAdmin(admin.ModelAdmin):
    '''
    定义Book管理需要显示的内容
    '''
    list_display = ['id','book_name','author_name','publish_date']
    list_filter = ['book_name']
    search_fields = ['id','book_name','author_name','publish_date']
    list_per_page = 5
    fieldsets = [
        ("基本信息",{ 'fields': [ 'book_name'] }),
        ("书本更多",{ 'fields': [ 'author_name','publish_date' ]})
    ]
    inlines = [HeroInline]

class HeroAdmin(admin.ModelAdmin):
    '''
    定义Hero管理需要现实的内容
    '''
    list_display = ['id','hero_name','hero_sex','hero_content','hero_book']
    search_fields = ['id','hero_name','hero_sex','hero_content','hero_book']
    list_filter = ['hero_name']
    list_per_page = 5
    fieldsets = [
        ("基本信息", {'fields': [ 'hero_name','hero_sex' ]}),
        ("英雄更多", {'fields': [ 'hero_content','hero_book' ]})
    ]

admin.site.register(Book,BookAdmin)
admin.site.register(Hero,HeroAdmin)

可以实现在修改/添加页面中，效果如下：

待续...

人本性懒惰，能战胜懒惰者，少，能长时间坚持者，更少!