标签：john 开发 xtend recent name splay 创建数据库 oom writing
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
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 models
class Reporter(models.Model):
full_name = models.CharField(max_length=70)
def __str__(self): # __unicode__ on Python 2
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): # __unicode__ on Python 2
return self.headline
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
1) 导入
from news.models import Reporter, Article
2) 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.id
1
>>> 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.id
16 1
17
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_name
24 ‘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.reporter
16 >>> r.full_name
17 ‘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 efficient
24 # 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()
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 admin
from . import models
admin.site.register(models.Article)
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 url
from . import views
urlpatterns = [
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‘)
编写范例如下
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)
最后返回的时候的html文件就用到了模板系统
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" }}
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="{% static "images/sitelogo.png" %}" alt="Logo" />
{% block content %}{% endblock %}
</body>
</html>
继承代码为
{% extends "base.html" %}
标签：john 开发 xtend recent name splay 创建数据库 oom writing
原文地址：http://www.cnblogs.com/weihuchao/p/7073769.html
