2014_07_28_Django環境安裝以及 Django Book Chapter 4: Templates

Mac 環境安裝 &
Chapter 4: Templates
2014.07.28 @NCU BY LOUIS

Mac
• Mac OS 10
• python 2.7.8
• virtualenv & virtualenvwrapper
• ipython
• Django

安裝python
• 官網下載dkg

virtualenv & virtualenvwrapper
• 介紹
• 安裝
– sudo pip install virtualenv
– sudo pip install virtualenvwrapper
– source /usr/local/bin/virtualenvwrapper.sh
• 使用方式
– $ virtualenv ENV
http://www.openfoundry.org/tw/tech-column/8516-pythons-virtual-environment-
and-multi-version-programming-tools-virtualenv-and-pythonbrew

ipython
• sudo pip install readline ipython

Chapter 4: Templates
• View 與 python的銜接(Templates)
• 基本的tags
• Views V.S. Templates
• Using templates

Why do we use a template?
• hard-code HTML 的缺點
– 若版面更改，往往會需要動道Python code
– 開發中Python coders 與 HTML/CSS coders 幾乎
是分開的
– 利用templates將會更有效率

Template System Basics
<html>
<head><title>Ordering notice</title></head>
<body>
<h1>Ordering notice</h1>
Dear {{ person_name }},
Thanks for placing an order from {{ company }}. It's scheduled to
ship on {{ ship_date|date:"F j, Y" }}.
Here are the items you've ordered:

<ul>
{% for item in item_list %}
<li>{{ item }}</li>
{% endfor %}
</ul>
{% if ordered_warranty %}
Your warranty information will be included in the packaging.
{% else %}
You didn't order a warranty, so you're on your own when
the products inevitably stop working.
{% endif %}
Sincerely, {{ company }}
</body>
</html>

Using the Template System
• Create a Template object
• Call the render() with a given variables(the
context)
>>> from django import template
>>> t = template.Template('My name is {{ name }}.')
>>> c = template.Context({'name': 'Adrian'})
>>> print t.render(c)
My name is Adrian.
>>> c = template.Context({'name': 'Fred'})
>>> print t.render(c)
My name is Fred.

An example of template
compilation & rendering
>>> from django.template import Template, Context
>>> raw_template = """Dear {{ person_name }},
...
... Thanks for placing an order from {{ company }}. It's scheduled to
... ship on {{ ship_date|date:"F j, Y" }}.
...
... {% if ordered_warranty %}
... Your warranty information will be included in the packaging.
... {% else %}
... You didn't order a warranty, so you're on your own when
... the products inevitably stop working.
... {% endif %}
...
... Sincerely, {{ company }}"""

>>> t = Template(raw_template)
>>> import datetime
>>> c = Context({'person_name': 'John Smith',
... 'company': 'Outdoor Equipment',
... 'ship_date': datetime.date(2009, 4, 2),
... 'ordered_warranty': False})
>>> t.render(c)
u"Dear John Smith,nnThanks for placing an order from Outdoor
Equipment. It's scheduled tonship on April 2, 2009.nnnYou
didn't order a warranty, so you're on your own whennthe products
inevitably stop working.nnnSincerely, Outdoor Equipment
"

Multiple Contexts, Same Template
>>> t = Template('Hello, {{ name }}')
>>> print t.render(Context({'name': 'John'}))
Hello, John
>>> print t.render(Context({'name': 'Julie'}))
Hello, Julie
>>> print t.render(Context({'name': 'Pat'}))
Hello, Pat
# Bad
for name in ('John', 'Julie', 'Pat'):
t = Template('Hello, {{ name }}')
print t.render(Context({'name': name}))
# Good
t = Template('Hello, {{ name }}')
for name in ('John', 'Julie', 'Pat'):
print t.render(Context({'name': name}))

>>> person = {'name': 'Sally', 'age': '43'}
>>> t = Template('{{ person.name }} is {{ person.age }} years old.')
>>> c = Context({'person': person})
>>> t.render(c)
u'Sally is 43 years old.'

Tags & Filters
• if/else
– {% if %}…{% endif %}
• for
– {% for %}…{% endfor %}
– {% for athlete in athlete_list reversed %}
• ifqual/ifnotequal
– {% ifequal variable value%}
• Comments
– {# This is a comment#}
• Filters
– {{ ship_date|date:"F j, Y" }}

WEB SERVER
VIEW LAYER
TEMPLATES
MODEL LAYER & ORM
DATABASE
Django

Using Templates in Views
from django.http import HttpResponse
import datetime
def current_datetime(request):
now = datetime.datetime.now()
html = "<html><body>It is now %s.</body></html>" %
now
return HttpResponse(html)
from django.template import Template, Context
import datetime
t = Template("<html><body>It is now {{ current_date
}}.</body></html>")
html = t.render(Context({'current_date': now}))
from django.template import Template, Context
import datetime
# Simple way of using templates from the filesystem.
# This is BAD because it doesn't account for missing files!
fp = open('/home/djangouser/templates/mytemplate.html')
t = Template(fp.read())
fp.close()

Template Loading
• settings.py -> TEMPLATE_DIRS
– TEMPLATE_DIRS = (
'/home/django/mysite/templates’,
)
from django.template.loader import get_template
from django.template import Context
import datetime
t = get_template('current_datetime.html')

• render_toresponse()
from django.shortcuts import render_to_response
import datetime
return render_to_response('current_datetime.html',
{'current_date': now})

2014_07_28_Django環境安裝以及 Django Book Chapter 4: Templates

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