2019独角兽企业重金招聘Python工程师标准>>> 
地址：
https://docs.djangoproject.com/en/2.0/intro/overview/
设计模型，可以通过模型做增删改查，而不用面向数据库
列：
from django.db import models
class Reporter(models.Model):
full_name = models.CharField(max_length=70)
def __str__(self):
return self.full_name
class Article(models.Model):
pub_date = models.DateField()
headline = models.CharField(max_length=200)
content = models.TextField()
reporter = models.ForeignKey(Reporter, on_delete=models.CASCADE)
def __str__(self):
return self.headline
python manage.py migrate
migrate 能根据模型在数据中创建不存在的表。
于是就能愉快的使用api来操作数据库。
1，获取所有对象：
Reporter.objects.all()
2，创建对象 后会自己生成id号
r = Reporter(full_name='John Smith')
r.save()
# Now it has an ID. >>> r.id 1
3，查询单个对象，通过id或者匹配内容
>>> Reporter.objects.get(id=1)
<Reporter: John Smith>
>>> Reporter.objects.get(full_name__startswith='John')
<Reporter: John Smith>
>>> Reporter.objects.get(full_name__contains='mith')
<Reporter: John Smith>
>>> Reporter.objects.get(id=2)
Traceback (most recent call last):
...
DoesNotExist: Reporter matching query does not exist.
3，创建关联对象
>>> from datetime import date >>> a = Article(pub_date=date.today(), headline='Django is cool', ... content='Yeah.', reporter=r) >>> a.save()
4，查关联对象
>>> r = a.reporter >>> r.full_name 'John Smith'
5，通过类方法，查询
>>> Article.objects.filter(reporter__full_name__startswith='John') <QuerySet [<Article: Django is cool>]>
6，删除对象
# Delete an object with delete(). >>> r.delete()
7，通过在admin内容管理注册你的模型，便可在admin页面里面管理模型对应数据的增删改查，方法如下。这里的设计理论是为了做简单管理内容。django 快速开发内容管理后台就是用到这里，非常快捷方便的实现用户，内容管理。
mysite/news/admin.py
from . import models admin.site.register(models.Article)
8，url地址对应关系设置
mysite/news/urls.py
from django.urls import path
from . import views
urlpatterns = [
path('articles/<int:year>/', views.year_archive),
path('articles/<int:year>/<int:month>/', views.month_archive),
path('articles/<int:year>/<int:month>/<int:pk>/', views.article_detail),
]
For example, if a user requested the URL “/articles/2005/05/39323/”, Django would call the functionnews.views.article_detail(request, year=2005, month=5, pk=39323).
9,编写view 对应方法，返回一个response或者http404,这里使用了模板
mysite/news/views.py
from django.shortcuts import render
from .models import Article
def year_archive(request, year):
a_list = Article.objects.filter(pub_date__year=year)
context = {'year': year, 'article_list': a_list}
return render(request, 'news/year_archive.html', context)
10，设计模板，需要在setting列出模板的路径dirs的列表，一个没找到会在下一个里面寻找。
mysite/news/templates/news/year_archive.html
加载基础html,对象循环
mysite/news/templates/news/year_archive.html
{% extends "base.html" %}
{% block title %}Articles for {{ year }}{% endblock %}
{% block content %}
<h1>Articles for {{ year }}</h1>
{% for article in article_list %}
<p>{{ article.headline }}</p>
<p>By {{ article.reporter.full_name }}</p>
<p>Published {{ article.pub_date|date:"F j, Y" }}</p>
{% endfor %}
{% endblock %}
{{ article.pub_date|date:"F j, Y" }} uses a Unix-style “pipe” (the “|” character). This is called a template filter, and it’s a way to filter the value of a variable. In this case, the date filter formats a Python datetime object in the given format，模组里面的filter
mysite/templates/base.html
{% load static %}
<html>
<head>
<title>{% block title %}{% endblock %}</title>
</head>
<body>
<img src="{% static "images/sitelogo.png" %}" alt="Logo" />
{% block content %}{% endblock %}
</body>
</html>
base.html里面里面是一些通用的元素
其他特征：
1，缓存框架的后台
2，一个联合框架，使得创建RSS和Atom提要和编写一个小Python类一样容易。