INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'rango',#添加内容,告诉框架我们新添加了这个应用
]

#edit in rango/views.py
def index(request):
    return HttpResponse("Rango says hey there partner! <br/> <a href='/rango/about'>About</a>")

def about(request):
    return HttpResponse("Rango says here is the about page. <br/> <a href='/rango/'>Index</a>")

#edit in project/urls.py
from django.urls import include, path
from django.contrib import admin
from rango import views
urlpatterns = [
    #将以rango/ 为开头的url交给rango应用处理
    path('rango/', include('rango.urls')),
    path("admin/", admin.site.urls),
]

#edit in rango/urls.py
from django.urls import path
from rango import views

urlpatterns = [
    #只要匹配到"rango/ "空字符串，就会调用views.index()视图函数
    path('', views.index, name='index'),
    path('about/', views.about, name='about'),
]

from django.db import models
from django.template.defaultfilters import slugify
# Create your models here.
#分类模型
class Category(models.Model):
    name=models.CharField(max_length=128,unique=True)
    views=models.IntegerField(default=0)
    likes=models.IntegerField(default=0)
    slug = models.SlugField(default='',blank=True)
    def save(self, *args, **kwargs):
        self.slug = slugify(self.name)
        super(Category, self).save(*args, **kwargs)
    class Meta:
        verbose_name_plural='Categories'

    def __str__(self):
        return self.name
#ForeignKey建立一对多关系 字段需要一个 on_delete 参数,
# 这是 Django 2.0 以后的要求。on_delete 
# 参数用于指定当关联的 Category 对象被删除时,应该如何处理关联的 Page 对象
class Page(models.Model):
    category=models.ForeignKey(Category,models.CASCADE)
    title=models.CharField(max_length=128)
    url=models.URLField()
    views=models.IntegerField(default=0)

    def __str__(self):
        return self.title

import os
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'tango_with_django_project.settings')

import django
django.setup()
from rango.models import Category, Page

def populate():
# 首先创建一些字典,列出想添加到各分类的网页
# 然后创建一个嵌套字典,设置各分类
# 这么做看起来不易理解,但是便于迭代,方便为模型添加数据
    python_pages = [
    {"title": "Official Python Tutorial",
    "url":"http://docs.python.org/2/tutorial/"},
    {"title":"How to Think like a Computer Scientist",
    "url":"http://www.greenteapress.com/thinkpython/"},
    {"title":"Learn Python in 10 Minutes",
    "url":"http://www.korokithakis.net/tutorials/python/"} ]
    django_pages = [
    {"title":"Official Django Tutorial",
    "url":"https://docs.djangoproject.com/en/1.9/intro/tutorial01/"},
    {"title":"Django Rocks",
    "url":"http://www.djangorocks.com/"},
    {"title":"How to Tango with Django",
    "url":"http://www.tangowithdjango.com/"} ]
    other_pages = [
    {"title":"Bottle",
    "url":"http://bottlepy.org/docs/dev/"},
    {"title":"Flask",
    "url":"http://flask.pocoo.org"} ]


    cats = {
    "Python": {"pages": python_pages
    ,"views":128,"likes":64},
    "Django": {"pages": django_pages
    ,"views":64,"likes":32},
    "Other Frameworks": {"pages": other_pages
    ,"views":32,"likes":6} 
    }

    for cat, cat_data in cats.items():
        c = add_cat(cat,cat_data["views"],cat_data["likes"])
        for p in cat_data["pages"]:
            add_page(c, p["title"], p["url"])
        #打印添加的分类
    for c in Category.objects.all():
        for p in Page.objects.filter(category=c):
            print("- {0} - {1}".format(str(c), str(p)))

def add_page(cat, title, url, views=0):
    p = Page.objects.get_or_create(category=cat, title=title)[0]
    p.url=url
    p.views=views
    p.save() #p.save()：这行代码将 Page 对象保存到数据库。
    return p

def add_cat(name,views,likes):
    c = Category.objects.get_or_create(name=name,views=views,likes=likes)[0]
    c.save()
    return c

# 从这开始执行
if __name__ == '__main__':
    print("Starting Rango population script...")
    populate()

from django.urls import path
from django.urls import re_path #用于正则表达式
from rango import views
from django.conf import settings
from django.conf.urls.static import static

urlpatterns = [
    #只要匹配到"rango/ "空字符串，就会调用views.index()视图函数
    path('', views.index, name='index'),
]
if settings.DEBUG:
    urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)

from django.shortcuts import render
from django.http import HttpResponse
from rango.models import Category
from rango.models import Page 

def index(request):
    # 查询数据库，获取目前存储的所有分类
    # 按点赞次数倒序排列分类
    # 获取前 5 个分类（如果分类数少于 5 个，那就获取全部）
    # 把分类列表放入 context_dict 字典
    # 稍后传给模板引擎
    category_list = Category.objects.order_by('-likes')[:5]
    pages_list = Page.objects.order_by('-views')[:5]
    context_dict = {'categories': category_list,
                    'most_liked_category':category_list.first(),
                    'most_viewd_pages':pages_list}
    # 渲染响应，发给客户端
    return render(request, 'rango/index.html', context_dict)
    
def about(request):
    #打印请求方法，GET/POST
    print(request.method)
    #打印用户名
    print(request.user)
    return render(request, "rango/about.html",{})

def show_category(request, category_name_slug):
    # 创建上下文字典，稍后传给模板渲染引擎
    context_dict = {}
    try:
        # 能通过传入的分类别名找到对应的分类吗？
        # 如果找不到，.get() 方法抛出 DoesNotExist 异常
        # 因此 .get() 方法返回一个模型实例或抛出异常
        category = Category.objects.get(slug=category_name_slug)
        # 检索关联的所有网页
        # 注意，filter() 返回一个网页对象列表或空列表
        pages = Page.objects.filter(category=category)
        # 把得到的列表赋值给模板上下文中名为 pages 的键
        context_dict['pages'] = pages
        # 也把从数据库中获取的 category 对象添加到上下文字典中
        # 我们将在模板中通过这个变量确认分类是否存在
        context_dict['category'] = category
    except Category.DoesNotExist:
        # 没找到指定的分类时执行这里
        # 什么也不做
        # 模板会显示消息，指明分类不存在
        context_dict['category'] = None
        context_dict['pages'] = None
        # 渲染响应，返回给客户端
    return render(request, 'rango/category.html', context_dict)      

class Category(models.Model):
    name=models.CharField(max_length=128,unique=True)
    views=models.IntegerField(default=0)
    likes=models.IntegerField(default=0)
    slug = models.SlugField(default='',blank=True)
    def save(self, *args, **kwargs):
        self.slug = slugify(self.name)
        super(Category, self).save(*args, **kwargs)
    class Meta:
        verbose_name_plural='Categories'

    def __str__(self):
        return self.name

from django.urls import path
from django.urls import re_path #用于正则表达式
from rango import views
from django.conf import settings
from django.conf.urls.static import static

urlpatterns = [
    #只要匹配到"rango/ "空字符串，就会调用views.index()视图函数
    path('', views.index, name='index'),
    path('about/', views.about, name='about'),
    re_path(r'^category/(?P<category_name_slug>[\w\-]+)/$',
            views.show_category, name='show_category'),
    #(?P<category_name_slug>[\w\-]+)/$ 是一个正则表达式，
    # 它会匹配 URL 中的一部分，并将其作为 category_name_slug 参数传递给 show_category 视图函数。
]
if settings.DEBUG:
    urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)