首页 > 代码库 > 02 - 看一眼Django都有啥
02 - 看一眼Django都有啥
Django是源自于fast-paced newsroom environment
因此Django的目的就是为了使得web开发变得简单有效
下面的内容是一个用Django开发的a database-driven Web app
1 设计你的模型
你可以使用没有数据库的Django
但是如果使用数据库的话, 由于Django提供了ORM( object-relational mapper )这个能解决很多数据库问题的数据模型
你可以
mysite/news/models.py
from django.db import modelsclass Reporter(models.Model): full_name = models.CharField(max_length=70) def __str__(self): # __unicode__ on Python 2 return self.full_nameclass 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): # __unicode__ on Python 2 return self.headline2 根据这个模型创建数据库表
python manage.py migrate该命令执行的时候, 会查看所有可用的模型, 然后在数据库中创建相应不存在的表和optionally providing much richer schema control
3 使用Python代码操作数据库
1) 导入
from news.models import Reporter, Article2) 查询所有内容, 返回的是QuerySet对象, 处理类似于集合的处理方式
表名.onjects.all()>>> Reporter.objects.all()<QuerySet [<Reporter: John Smith>]>查询指定列用get()
传入的参数是一个表达式, 可以使用特殊__startswith, __contains来获取以开始, 包含
>>> 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>添加条件过滤用filter()
>>> Article.objects.filter(reporter__full_name__startswith=‘John‘)<QuerySet [<Article: Django is cool>]>3) 新增数据
# Create a new Reporter.>>> r = Reporter(full_name=‘John Smith‘)# Save the object into the database. You have to call save() explicitly.>>> r.save()# Now it has an ID.>>> r.id1>>> from datetime import date>>> a = Article(pub_date=date.today(), headline=‘Django is cool‘,... content=‘Yeah.‘, reporter=r)>>> a.save()# Article objects get API access to related Reporter objects.>>> r = a.reporter>>> r.full_name‘John Smith‘4) 删除数据
# Delete an object with delete().>>> r.delete()对Repoter表的操作
1 # Import the models we created from our "news" app 2 >>> from news.models import Reporter, Article 3 4 # No reporters are in the system yet. 5 >>> Reporter.objects.all() 6 <QuerySet []> 7 8 # Create a new Reporter. 9 >>> r = Reporter(full_name=‘John Smith‘)10 11 # Save the object into the database. You have to call save() explicitly.12 >>> r.save()13 14 # Now it has an ID.15 >>> r.id16 117 18 # Now the new reporter is in the database.19 >>> Reporter.objects.all()20 <QuerySet [<Reporter: John Smith>]>21 22 # Fields are represented as attributes on the Python object.23 >>> r.full_name24 ‘John Smith‘25 26 # Django provides a rich database lookup API.27 >>> Reporter.objects.get(id=1)28 <Reporter: John Smith>29 >>> Reporter.objects.get(full_name__startswith=‘John‘)30 <Reporter: John Smith>31 >>> Reporter.objects.get(full_name__contains=‘mith‘)32 <Reporter: John Smith>33 >>> Reporter.objects.get(id=2)34 Traceback (most recent call last):35 ...36 DoesNotExist: Reporter matching query does not exist.对Article表的操作
1 # Import the models we created from our "news" app 2 >>> from news.models import Reporter, Article 3 4 # Create an article. 5 >>> from datetime import date 6 >>> a = Article(pub_date=date.today(), headline=‘Django is cool‘, 7 ... content=‘Yeah.‘, reporter=r) 8 >>> a.save() 9 10 # Now the article is in the database.11 >>> Article.objects.all()12 <QuerySet [<Article: Django is cool>]>13 14 # Article objects get API access to related Reporter objects.15 >>> r = a.reporter16 >>> r.full_name17 ‘John Smith‘18 19 # And vice versa: Reporter objects get API access to Article objects.20 >>> r.article_set.all()21 <QuerySet [<Article: Django is cool>]>22 23 # The API follows relationships as far as you need, performing efficient24 # JOINs for you behind the scenes.25 # This finds all articles by a reporter whose name starts with "John".26 >>> Article.objects.filter(reporter__full_name__startswith=‘John‘)27 <QuerySet [<Article: Django is cool>]>28 29 # Change an object by altering its attributes and calling save().30 >>> r.full_name = ‘Billy Goat‘31 >>> r.save()32 33 # Delete an object with delete().34 >>> r.delete()4 动态管理接口
Django提供了功能完善的管理接口(administrative interface)
需要在admin.py中添加配置
mysite/news/admin.py
from django.contrib import adminfrom . import modelsadmin.site.register(models.Article)5 URLs的编写(URL调度程序)
这个urls.py文件可以将URL的模式匹配与其相应的回调函数一一对应, 从而分离代码
mysite/news/urls.py
from django.conf.urls import urlfrom . import viewsurlpatterns = [ url(r‘^articles/([0-9]{4})/$‘, views.year_archive), url(r‘^articles/([0-9]{4})/([0-9]{2})/$‘, views.month_archive), url(r‘^articles/([0-9]{4})/([0-9]{2})/([0-9]+)/$‘, views.article_detail),]这些是一些正则匹配来匹配输入的URL
正则表达式中的括号可以获取匹配成功的值
匹配的过程是从前往后依次匹配, 一旦匹配成功, 就会调用相应的view函数处理, 如果到最后都还时没有匹配成功, 那么就会返回特殊的视图404
传递给view函数的有一个请求对象, 和上述中括号正则表达式捕获到的值
/articles/2005/05/39323/news.views.article_detail(request, ‘2005‘, ‘05‘, ‘39323‘)6 编写视图(views)
编写范例如下
mysite/news/views.py
from django.shortcuts import renderfrom .models import Articledef 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)最后返回的时候的html文件就用到了模板系统
7 编写模板
在Django中可以设置一个目录列表, 里面有一个个存放模板的目录(具体设置方法)
当查找模板的时候就依照顺序在这些目录中找
具体模板文件有
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 %}具体语法有
1) 值的获取
{{ year }}可以通过点的方式, 来进行属性查找, 字典的键查找, 索引查找 和 函数调用
{{ article.headline }}2) 模板过滤器(template filter)
变量后面用 | 来进行一下处理的方式, 类似于linux中的管道
格式化时间的方式如下
{{ article.pub_date|date:"F j, Y" }}还可以自定义模板过滤器, 自定义模板标签
3) 模板继承
基本模板( base templates )如下
mysite/templates/base.html
{% load static %}<html><head> <title>{% block title %}{% endblock %}</title></head><body> <img src="http://www.mamicode.com/{% static"images/sitelogo.png" %}" alt="Logo" /> {% block content %}{% endblock %}</body></html>继承代码为
{% extends "base.html" %}
02 - 看一眼Django都有啥
声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉： 投诉/举报 工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。