第六章 Django实例
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1.1 展示
1. 创建数据库
#打开cmd窗口,在 命令行,mysql中 create database dj_bookmanager
2. settings.py
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BASE_DIR:项目根目录
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debug = True(开发) / False(上线)
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INSTALL_APPS:注册app
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TEMPLATES:模版文件目录
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DATABASES:配置mysql数据库(6)
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STATICFILES_DIRS:配置静态文件
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在__init.py中导入pymysql模块,替换默认链接方式
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并创建model类,并指定约束
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models.AutoField(primary_key = True) #自增并指定主键
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models.CharField(max_length=32, unqiue/default=xxx)
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models.IntegerField(default=0)
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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})
7. xxx.html
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这里使用的是django的渲染语法(在创建app也可以指定jinja2)
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{{变量}},{% for 循环%}{%endfor%}(需要闭合)
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{# 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 %}
1.2 新增
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models.类名.objects.create(字段=值)
# orm插入数据 obj = models.Publisher.objects.create(name=publisher_name) # publisher object print(obj)
- 实例化方式
obj = models.Publisher(name=publisher_name) obj.save() # 保存到数据库中 # obj打印结果:Publisher obj print(obj)
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obj.delete(),obj_list.delete()
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对像和对象列表都有delete方法
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()
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obj.字段=值
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obj.save() 更新数据到数据库
# 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()
2. 书籍管理
1. book表
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name、作者、出版社、出版时间
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
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models.py
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models中的pub是被关联类的对象
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django会自动生成 pub_id
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})
2.4 新增
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})
2.5 删除
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数据库查询到的对象 或 query set 都可以使用delete方法直接删除数据
def del_book(request): if request.method == ‘GET‘: pk = request.GET.get(‘id‘) models.Book.objects.filter(id=pk).delete() return redirect(‘/list_book/‘)
2.6 修改
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获取的 pub_id 是 str 类型,注意和数据库中字段类型一样
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})
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