python 之 Django框架(APP和ORM的使用)

python3 manage.py startapp app01

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

DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.mysql",
        "NAME": "db6",              # 需要自己手动先创建数据库
        "USER": "root",
        "PASSWORD": "",
        "HOST": "127.0.0.1",
        "PORT": 3306
    }
}

import pymysql
pymysql.install_as_MySQLdb()

from django.db import models
​
class User(models.Model):
    id = models.AutoField(primary_key=True)  # 自增主键
    name = models.CharField(max_length=16)   # varchar(16)
    pwd = models.CharField(max_length=128)   # varchar(128)
​
# 出版社    
class Publisher(models.Model):
    id = models.AutoField(primary_key=True)   # 自增主键
    name = models.CharField(max_length=16)    # varchar(16) # 出版社名称
​
    #def __str__(self):                     #定义__str__是在打印表的对象时可以看到每一行的字段
    #    return (self.id,self.name)
​
# 书籍
class Book(models.Model):
    id = models.AutoField(primary_key=True)        # 自增的主键
    title = models.CharField(max_length=32)        # 书籍名称 varchar(32)
    publisher = models.ForeignKey(to="Publisher")  # 外键关联Publisher这张表
​
# 作者
class Author(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=16)
    books = models.ManyToManyField(to="Book")
    # ORM创建多对多字段，会自动在数据库中创建第三张表 id Author_id、Book_id

1. python3 manage.py makemigrations    --> 将models.py的修改登记到小本本上
2. python3 manage.py migrate           --> 将修改翻译成SQL语句，去数据库执行

from django.conf.urls import url
from django.contrib import admin
from app01 import views
​
# 对应关系
urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^login/', views.login),
    url(r'^publisher_list/', views.publisher_list),       # 展示出版社列表
    url(r'^add_publisher/', views.add_publisher),        # 添加出版社
    url(r'^delete_publisher/', views.delete_publisher),  # 删除出版社
    url(r'^edit_publisher/', views.edit_publisher),      # 编辑出版社
    url(r'^book_list/', views.book_list),               # 书籍列表
    url(r'^add_book/', views.add_book),                 # 添加书籍
    url(r'^delete_book/', views.delete_book             # 删除书籍
    url(r'^edit_book/', views.edit_book),               # 编辑书籍
    url(r'^author_list/', views.author_list),            # 作者列表
    url(r'^add_author/', views.add_author),             # 添加作者
    url(r'^delete_author/', views.delete_author),       # 删除作者
    url(r'^edit_author/', views.edit_author),           # 编辑作者
    url(r'^$', views.publisher_list)                   # 以上对应关系都找不到，就匹配出版社页面
]

from django.shortcuts import HttpResponse, render, redirect
from app01 import models
# 显示出版社列表
def publisher_list(request):
    ret = models.Publisher.objects.all()    # 从数据库中取出所有的数据对象列表
    #print(ret)
    return render(request, "publisher_list.html", {"publisher_list": ret})
​
#添加出版社函数
def add_publisher(request):     # 根据请求方法的不同，要做不同的事情,add_publisher.html使用POST方法
    if request.method == "POST":#request.method获取的是请求的方法(GET、POST...必须是大写)
        #request.POST(字典)获取POST提交过来的全部数据
        new_publisher_name = request.POST.get("publisher_name")
        models.Publisher.objects.create(name=new_publisher_name)#创建对象并封装属性(插入一行数据)
        #或者自己用类实例化一个对象:obj=models.Publisher(name=new_publisher_name) obj.save()
        #让用户跳转到publisher_list.html，显示新增数据后的publisher_list.html页面
        return redirect("/publisher_list/")
    return render(request, "add_publisher.html")
​
# 删除出版社函数
def delete_publisher(request):
    #print(request.method)
    #print(request.GET)
    delete_id = request.GET.get("id")              #拿到用户要删除的出版社的id值
    #print(delete_id)
    obj = models.Publisher.objects.get(id=delete_id)#根据id值得到对象
    obj.delete()                                 #将数据删除
    return redirect("/publisher_list/")            #让用户重新访问publisher_list.html更新页面
​
# 编辑出版社的函数
def edit_publisher(request):
 #edit_id = request.GET.get("id")如果用户提交使用URL拼接id，那么从URL里面取id参数request.GET.get("id")
    if request.method == "POST":    #如果是post请求，表示用户已经编辑好了，向服务端提交修改后的新数据
        edit_id = request.POST.get("edit_id")  # 拿到已经修改的出版社id
        new_name = request.POST.get("name")    # 拿到修改之后的出版社的名字
        edit_obj = models.Publisher.objects.get(id=edit_id)#通过id找到数据行对象
        edit_obj.name = new_name
        edit_obj.save()                      #保存修改，提交数据库
        return redirect("/publisher_list/")    # 修改成功，让用户跳转到出版社列表页面，更新页面
​
    #如果不是post请求，则返回edit_publisher.html页面给用户修改出版社
    edit_id = request.GET.get("id")                #先获取编辑的出版社的ID值
    obj = models.Publisher.objects.get(id=edit_id)  #根据id值去数据库找对应的行数据对象
    return render(request, "edit_publisher.html", {"publisher": obj})#将数据想要编辑的出版社显示出来，等待用户编辑

<body>
<table border="1">
    <thead>
    <tr>
        <th>#</th>
        <th>出版社名称</th>
    </tr>
    </thead>
    <tbody>
    {% for publisher in publisher_list %}
    <tr>
        <td>{{ publisher.id }}</td>     #{{ forloop.counter }计数表格中的数据条数，从而删除后更新id
        <td>{{ publisher.name }}</td>
        <td class="text-center">
            <a class="btn btn-info btn-sm" href="/edit_publisher/?id={{ publisher.id }}">
            <i class="fa fa-pencil fa-fw" aria-hidden="true"></i> 编辑 </a>
            <a class="btn btn-danger btn-sm" href="/delete_publisher/?id={{ publisher.id }}">
            <i class="fa fa-trash-o fa-fw" aria-hidden="true"></i>删除 </a>
        </td>
    </tr>
    {% endfor %}
    </tbody>
</table>
</body>