第六章 Django实例

#打开cmd窗口，在 命令行，mysql中
create database dj_bookmanager

from django.db import models

class Publisher(models.Model):
  pid = models.AutoField(primary_key = True)
  name = models.CharField(max_length=32, unique=True)
  # 后续添加，需要指定默认值
  addr = models.CharField(max_length=32, default=‘xxx‘)
  # 或者更改迁移文件

python manage.py makemigrations
python manage.py migrate
# 插入数据

from django.conf.urls import url
from django.contrib import admin
# 导入视图模块
from app1 import views
# 添加调用关系
urlpatterns = [
    url(r‘^admin/‘, admin.site.urls),
    url(r‘login‘, views.publisher_list),
]

from django.shortcuts import render, HttpResponse, redirect
def publisher_list(request):
  # 业务逻辑
    all_pubulisher = models.Pbulisher.objects.all().order_by(pk)
    return render(request, ‘publisher_list.html‘, {‘all_pubulisher‘:all_pubulisher})

{# for循环中有 forloop.counter 自动记录循环次数 #}
{% for publisher in all_publisher %}
    <tr>
    <td>{{forloop.counter}}</td>
    <td>{{publisher.pid/pk}}</td>
    <td>{{publisher.name}}</td>
    </tr>
{% endfor %}
{# if条件判断 #}
{% if 条件判断 %}
{% else %} / {% elif %}
{% endif %}

# orm插入数据
obj = models.Publisher.objects.create(name=publisher_name)
# publisher object
print(obj)

obj = models.Publisher(name=publisher_name)
obj.save()   # 保存到数据库中
# obj打印结果：Publisher obj
print(obj) 

pk = request.GET.get(‘id‘)
obj_list = models.Publisher.objects.filter(pk=pk)
# 删除对象
if not obj_list:
  return HttpResponse(‘删除数据不存在‘)
obj_list.delete()

# 从url中获取的参数，不是get请求的数据
pk = request.GET.get(‘id‘)
obj_list = models.Publiser.objects.filter(pk=pk)
if not obj_list:
  return HttpResponse(‘编辑数据不存在‘)

obj = obj_list[0]
# 内存中修改
obj.name = publisher_name
# 内存中数据，提交到数据库
obj.save()

class Book(models.Model):
  title = models.CharField(max_length=32)
  pub_id = models.ForeignKey(to=Publisher,on_delete=models.SET(字段))
  # on_delete=models.CASCADE（默认）
  # on_delete=models.SET(‘具体值’)
  # on_delete=models.SET_DEFAULT， defalut=‘xxx‘
  # on_delete=models.SET_NULL
    # on_delete参数在django2.0之后必填
  # 通过反射获取, on_delete默认级联删除
  pub = models.ForeignKey(‘Publisher‘, on_delete=models.SET_NULL)

python manage.py makemigrations
python manage.py migrate
# 外键名django自动加 _id
# django.migrations也会在数据库中创建

for book in all_Book.objects.all():
    # book类中属性
    print(book.pk)
    print(book.title)
    print(book.pub_id)
    print(book.pub, type(book.pub))
    # publisher中属性
    # print(book.pub_id)只需要出版社id，建议使用
    print(book.pub.pk)
    print(book.name)

for+table,自动补全，pycharm提供
# __str__方法
print(book.pub)

def list_book(request):
    all_books = models.Book.objects.all()
    return render(request, ‘list_book.html‘, {‘all_books‘: all_books})

def add_book(request):
    error = ‘‘
    if request.method == ‘POST‘:
        title = request.POST.get(‘book_name‘)
        pk = request.POST.get(‘id‘)
        print(title, pk)
        # 可以使用多个字段进行查找
        book_set = models.Book.objects.filter(title=title, pub_id=pk)
        if book_set:
            error = ‘书籍已存在‘
        if not title: error = ‘请输入书名‘
        if not error:
            models.Book.objects.create(title=title, pub_id=pk)
            return redirect(‘/list_book/‘)
    all_publisher = models.Publisher.objects.all()
    return render(request, ‘add_book.html‘, {‘all_publisher‘: all_publisher, ‘error‘: error})

def del_book(request):
    if request.method == ‘GET‘:
        pk = request.GET.get(‘id‘)
        models.Book.objects.filter(id=pk).delete()
        return redirect(‘/list_book/‘)

def edit_book(request):
    error = ‘‘
    pk = request.GET.get(‘id‘)
    book = models.Book.objects.get(pk=pk)
    if request.method == ‘POST‘:
        title = request.POST.get(‘book_name‘)
        # 获取的 pub_id 是 str 类型，注意和数据库中字段类型一样
        pub_id = request.POST.get(‘id‘)
        print(type(title), type(book.title), type(pub_id), type(book.pub_id))
        # 判断 书名+出版社 是否被修改
        if book.title == title and book.pub_id == int(pub_id):
            error = ‘未做任何修改‘
        if not title: error = ‘请输入书名‘
        # 判断 书名+出版社 是否唯一
        if models.Book.objects.filter(title=title, pub_id=pub_id):
            error = ‘该书籍已存在‘
        if not error:
            book.title = title
            book.pub_id = pub_id
            book.save()
            return redirect(‘/list_book/‘)
    all_publisher = models.Publisher.objects.all().order_by(‘pid‘)
    return render(request, ‘edit_book.html‘, {‘book‘: book, ‘all_publisher‘: all_publisher, ‘error‘: error})