第59天： Web 开发 Django 模型

# TestProject/settings.py

# Database
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}

# polls/models.py

from django.db import models


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('发布日期')


class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

# TestProject/settings.py

INSTALLED_APPS = [
    'polls.apps.PollsConfig',   #新增polls路径
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
]

# polls/views.py
from django.shortcuts import render

# Create your views here.
from django.http import HttpResponse
from polls.models import Choice, Question
from django.utils import timezone

def index(request):
    return HttpResponse("你好，这是一个投票页面。")

# 增加问题描述信息
def add(request):
    question = Question(question_text='双十一你在哪个平台剁手？',pub_date=timezone.now())
    question.save();
    return HttpResponse("新增投票成功！")

# polls/urls.py
from django.urls import path
from . import views

urlpatterns = [
    path('', views.index, name='index'),
    path('add', views.add, name='add'),    #新增add路由
]

# polls/views.py
# …… 省略部分代码

def query(request):
    # 通过objects这个模型管理器的all()获得所有数据行，相当于SQL中的SELECT * FROM question
    questionList = Question.objects.all()
    # 获取单个对象
    response2 = Question.objects.get(id=1)
    # 相当于SQL中的WHERE id=1，可设置条件过滤
    response3 = Question.objects.filter(id=1)
    #根据id字段排序
    response5 = Question.objects.order_by("id")

    res = ""
    # 遍历所有对象
    for q in questionList:
        res += str(q.id) + "." + q.question_text + " <br />"
    return HttpResponse("查询所有问题：<br />" + res)

# polls/urls.py
from django.urls import path
from . import views

urlpatterns = [
    path('', views.index, name='index'),
    path('add', views.add, name='add'),  
    path('query', views.query, name='query'),  #新增的query路由
]

# polls/views.py
# …… 省略部分代码

#修改数据
def update(request):
    question1 = Question.objects.get(id=1)
    question1.question_text = '天猫和京东你会选哪个？'
    question1.save()

    # 通过条件过滤的方式也可以更新一条或多条数据
    # Question.objects.filter(id=1).update(question_text='天猫和京东你会选哪个？')

    return HttpResponse("更新id=1：" + question1.question_text)

#删除数据
def delete(request):
    question2 = Question.objects.get(id=2)
    question2.delete()

    # 通过条件过滤的方式也可以删除一条或多条数据
    # Question.objects.filter(id=2).delete()

    # 删除所有数据
    # Question.objects.all().delete()

    res3 = ''
    questionList = Question.objects.all()
    # 遍历所有对象
    for q in questionList:
        res3 += str(q.id) + "." + q.question_text + " <br />"
    return HttpResponse("删除后查询：<br />" + res3)

# polls/urls.py
from django.urls import path
from . import views

urlpatterns = [
    path('', views.index, name='index'),
    path('add', views.add, name='add'),  
    path('query', views.query, name='query'), 
    path('update', views.update, name='update'),  # 新增update路由
    path('del', views.delete, name='del'),  # 新增del路由
]