The Definitive Guide to Django的笔记(6)

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按有用程度 按页码先后 最新笔记

Chapter 3: Views and URLconfs

irachex (去冬天的空岛)
Chapter 3: Views and URLconfs 自己用ASP.NET MVC 2已经很熟练了，所以有关MVC的内容和设计理念都很了解，主要是对语法点的摘抄感觉作者的命名有些奇怪，不知道是django有某种约定俗成还是怎么。按我的理解，书中的'views'指MVC中的Controller，书中的'templates'指MVC中的View，为了符合自己的习惯，我把这章称为Controllers and URLconfs。不知道之后的章节会不会推翻我的习惯 [update:看到Chapter 5，django这种叫MTV框.. (更多)
Chapter 3: Views and URLconfs
自己用ASP.NET MVC 2已经很熟练了，所以有关MVC的内容和设计理念都很了解，主要是对语法点的摘抄
感觉作者的命名有些奇怪，不知道是django有某种约定俗成还是怎么。按我的理解，书中的'views'指MVC中的Controller，书中的'templates'指MVC中的View，为了符合自己的习惯，我把这章称为Controllers and URLconfs。不知道之后的章节会不会推翻我的习惯
[update:看到Chapter 5，django这种叫MTV框架，Model，Template，View]
每个Controller函数至少要有一个参数，通常被叫作request。这是一个触发这个Controller、包含当前Web请求信息的对象，是类django.http.HttpRequest的一个实例。它必须是这个Controller的第一个参数。
```
from django.http import HttpResponse

def hello(request):
    return HttpResponse("Hello world")
```
settings.py包含一个ROOT_URLCONF配置用来指向自动产生的urls.py，用来配置URL。
```
from django.conf.urls.defaults import *
from mysite.views import hello, current_datetime, hours_ahead

urlpatterns = patterns('',
    (r'^$', home),
    (r'^hello/', hello),
    (r'^time/plus/(\d{1,2})/, hours_ahead),
)
```
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2011-03-10 19:58:23 回应

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CH2

Ryan.K (杀人于旷野。)

** The Django Book *** CH2 > django-admin.py startproject mysite __init__.py: A file required for perthon to treat mysite directory as a package. manage.py: A command-line unity that lets you interact with Django project in various ways. settings.py Settings/configuration for Django project. Urls.py: The urls fot the Django project **** Running the Dev Server > python man... (更多)

** The Django Book
*** CH2
> django-admin.py startproject mysite
__init__.py: A file required for perthon to treat mysite directory as a package.
manage.py: A command-line unity that lets you interact with Django project in various ways.
settings.py Settings/configuration for Django project.
Urls.py: The urls fot the Django project
**** Running the Dev Server
> python manage.py runserver
The server was on http://127.0.0.1:8000/
Change the Dev Server's Host or port:
>python manage.py runserver 0.0.0.0:8000
It will alow people visit your site with your IP address
*** CH3 Views and URLcontrol
TO see the sys.path
>>> import sys
>>> print sys.path
**** ragular expression
^ caret: require that the pattern marthes the start of the string
$ dollar: require that the pattern matches the end of string
The root: ('^$', my_homepage_view),
Sample:
^hello/ will match /hello/foo and /hello/bar
hello/$ will match /fool/bar/hello/ and foolhello/
*allow request without a trailing slash*
To set APPEND_SLASH True
else APPEND_SLASH False
# Regexes
.(dot) : any single character
\d : any single digit
[A-Z] : any character between A and Z
[a-z] : any character between a and z
[A-Za-z]: case-insenstive
+ : one or more of prev expression
[^/]+ : one or more charcters untill (and not include) a forward slash
? : zero or one of the prev expression(e.g \d? matches zero or one digits
*- : zero or more
{1,3} : between one and tree or prevexpression (e.g \d{1,3} match one ,two or threee digits)
*** Dynamic Content
(r'^time/plus/(\{1,2})/$', hours_ahead),
r is means a "raw string" -- its contents should not interpret backslashes.
/in normal Python strings, blackslashes are uesd for escaping special characters -such as in the string \n ./
def hours_head(respond,num):
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2011-10-05 00:35:55 回应

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第43页

适兕 (我开始鄙视我自己！)

When you create a Template object, the template system compiles the raw template code into an internal, optimized form, ready for rendering. 网站的Template，这是和程序分离的必要组件。 A Python dictionary is a mapping between known keys and variable values. A Context is similar to a diction- ary, but a Context provides additional functionality, Key, Value.多么永恒的组合。 Django... (更多)

When you create a Template object, the template system compiles the raw template code
into an internal, optimized form, ready for rendering.
网站的Template，这是和程序分离的必要组件。
A Python dictionary is a mapping between known keys and variable values. A Context is similar to a diction-
ary, but a Context provides additional functionality,
Key, Value.多么永恒的组合。
Django’s template parsing is quite fast. Behind the scenes, most of the parsing hap-
pens via a call to a single regular expression. This is in stark contrast to XML-based template
engines, which incur the overhead of an XML parser and tend to be orders of magnitude
slower than Django’s template-rendering engine.
我非常喜欢Behind the scenes. (收起)

2011-03-17 17:46:03 回应

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第28页

适兕 (我开始鄙视我自己！)

关于页面URL与view的简单描述： just write view functions and map them to URLs via URLconfs. the principle of loose coupling。这句话的意思是：松散都耦合原理。 URLconfs and views are loose coupling in action. one of Django’s core philosophies is that URLs should be beautiful. it’s strongly suggested that you use raw strings any time you’re defining a regu- lar expression in Python.... (更多)

关于页面URL与view的简单描述：
just write view functions and map them to URLs via URLconfs.
the principle of loose coupling。
这句话的意思是：松散都耦合原理。
URLconfs and views are loose coupling in action.
one of Django’s core philosophies is that URLs should be beautiful.
it’s strongly suggested that you use raw strings any time you’re defining a regu-
lar expression in Python.
程序员都是这么较真的吗？
In this example, the URLpattern was written first and the view was written second, but in the previous exam-
ples, the view was written first and then the URLpattern was written. Which technique is better? Well, every
developer is different.
If you’re a big-picture type of person, it might make the most sense to you to write all the URLpatterns
for your application at the same time, at the start of your project, and then code up the views. This has the
advantage of giving you a clear to-do list, and it essentially defines the parameter requirements for the view
functions you’ll need to write.
If you’re more of a bottom-up developer, you might prefer to write the views first and then anchor them
to URLs afterward. That’s OK, too.
In the end, it comes down to which technique fits your brain the best. Both approaches are valid.
不过我还是希望自己是那个有Big-picture的家伙。
each view always takes an HttpRequest object as its first parameter.
这是入口，没有此一切都是浮云。
URLpatterns使用的那个r的意思是 re, 就是我们常用的那个 import re.
urls.py中的每条正则表达式都需要用逗号隔开，如果你没有，那你就得去调试一番。
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2011-03-17 15:33:07 回应

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Chapter 4: Templates

irachex (去冬天的空岛)
Chapter 4: Templates 我很喜欢Django的Templates的设计哲学：业务逻辑应该和表现逻辑相对分开。我们将模板系统视为控制表现及表现相关逻辑的工具，仅此而已。模板系统不应提供超出此基本目标的功能。像.NET，php等耦合不够松。 Django 模板解析非常快捷。大部分的解析工作都是在后台通过对简短正则表达式一次性调用来完成。基于 XML 的模板引擎往往比 Django 模板渲染引擎要慢上几个数量级。所以使用同一template源渲染... (更多)
Chapter 4: Templates
我很喜欢Django的Templates的设计哲学：业务逻辑应该和表现逻辑相对分开。我们将模板系统视为控制表现及表现相关逻辑的工具，仅此而已。模板系统不应提供超出此基本目标的功能。像.NET，php等耦合不够松。
Django 模板解析非常快捷。大部分的解析工作都是在后台通过对简短正则表达式一次性调用来完成。基于 XML 的模板引擎往往比 Django 模板渲染引擎要慢上几个数量级。
所以使用同一template源渲染多个context，只进行一次模板创建然后多次调用render()方法渲染会更为高效
{{ variable }} 变量后可以加 . ，跟属性或方法（不加括号），但方法不能有参数，.也可以用于访问索引，{{ list.1 }}。.的查找顺序为字典、属性、方法、列表
下面的例子是使方法不能被模版调用
```
def delete(self):
    # Delete the account
delete.alters_data = True
```
{% template tag %}
if else endif，{% if %} 接受and,or,not关键字来对多个变量做判断，但不允许在同一个标签中同时使用 and和or
```
{% if today_is_weekend %}
    Welcome to the weekend!
{% else %}
    Get back to work.
{% endif %}
```
for endfor
```
{% for athlete in athlete_list reversed %}
    {{ athlete.name }}
{% empty %}
    There are no athletes. Only computer programmers.
{% endfor %}
反向迭代:reversed
列表为空:empty
forloop.counter：从1开始计循环次数
forloop.counter0：从0开始
forloop.revcounter：剩余
forloop.first ：布尔值，第一次循环时为True
forloop.last ：布尔值，最后一次循环时为True
forloop.parentloop：指向当前循环的上一级循环的 forloop 对象的引用（嵌套循环时）
```
ifequal/ifnotequal，只有模板变量，字符串，整数和小数可以作为 {% ifequal %} 标签的参数，其他任何类型，例如Python的字典类型、列表类型、布尔类型，不能用
```
{% ifequal section 'sitenews' %}
    <h1>Site News</h1>
{% else %}
    <h1>No News Here</h1>
{% endifequal %}
```
注释
```
{# single line comment #}
{% comment %}
{% endcomment %}
```
filter
```
{{ my_list|first|upper }}
{{ bio|truncatewords:"30" }}
```
配置templates目录，在settings.py中
```
import os.path
TEMPLATE_DIRS = (
    os.path.join(os.path.dirname(__file__), 'templates').replace('\\','/'),
)
```
渲染模版
```
from django.template.loader import get_template
from django.template import Context
from django.http import HttpResponse
import datetime

def current_datetime(request):
    now = datetime.datetime.now()
    t = get_template('current_datetime.html')
    html = t.render(Context({'current_date': now}))
    return HttpResponse(html)
```
简化
```
from django.shortcuts import render_to_response
import datetime

def current_datetime(request):
    now = datetime.datetime.now()
    return render_to_response('current_datetime.html', {'current_date': now})
```
包含其他template
```
{% include 'nav.html' %}
```
template继承
母板
```
<!DOCTYPE html> 
<html lang="en">
<head>
    <title>{% block title %}{% endblock %}</title>
</head>
<body>
    <h1>My helpful timestamp site</h1>
    {% block content %}{% endblock %}
    {% block footer %}
    <hr>
    <p>Thanks for visiting my site.</p>
    {% endblock %}
</body>
</html>
```
继承
```
{% extends "base.html" %}

{% block title %}The current time{% endblock %}

{% block content %}
<p>It is now {{ current_date }}.</p>
{% endblock %}
```
{% extends %} ，必须保证其为模板中的第一个模板标记
如果你需要访问父模板中的块的内容，使用 {{ block.super }}这个标签
多数情况下， {% extends %} 的参数应该是字符串，但是如果直到运行时方能确定父模板名，这个参数也可以是个变量。
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2011-03-10 20:17:14 回应

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Chapter 2: Getting Started

irachex (去冬天的空岛)
Chapter 2: Getting Started Django自带对PostgreSQL，SQLite 3，MySQL，Oracle的支持，作者推荐PostgreSQL 因为一个值得注意的例外是Django的可选GIS支持，它为PostgreSQL提供了强大的功能。）如果你不准备使用一些老旧系统，而且可以自由的选择数据库后端，我们推荐你使用PostgreSQL，它在成本、特性、速度和稳定性方面都做的比较平衡。 /代码内容已省略/ 从子目录中import时，在目.. (更多)
Chapter 2: Getting Started
Django自带对PostgreSQL，SQLite 3，MySQL，Oracle的支持，作者推荐PostgreSQL
因为
一个值得注意的例外是Django的可选GIS支持，它为PostgreSQL提供了强大的功能。）如果你不准备使用一些老旧系统，而且可以自由的选择数据库后端，我们推荐你使用PostgreSQL，它在成本、特性、速度和稳定性方面都做的比较平衡。
```
django-admin.py startproject mysite
python manage.py runserver 8080
```
从子目录中import时，在目录中建立__init__.py空文件
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2011-03-10 19:33:25 回应

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笔记是你写在书页留白边上的内容；是你阅读中的批注、摘抄及随感。

笔记必须是自己所写，不欢迎转载。摘抄原文的部分应该进行特殊标明。

>The Definitive Guide to Django

The Definitive Guide to Django的笔记(6)

按有用程度 按页码先后 最新笔记

Chapter 3: Views and URLconfs

CH2

第43页

第28页

Chapter 4: Templates

Chapter 2: Getting Started

按有用程度按页码先后最新笔记