##5.模板 ###5.1基本概念模板是一个文本用于分离文档的表现形式和和内容。模板定义了占位符以及各种用于规范改如何显示的各部分基本逻辑(模板标签)。模板通常用于产生HTML，Django的文档可以产生任何基于文档格式的文档。 >{{ varible }}变量 {% template_tag %}模板标签，仅通知模板系统完成某些工作例如：{% if true %} if标签 {% for i in item %} for标签 ####5.2使用模板系统 >Python中使用django模板的基本方式： >- 创建一个Template对象，Django同样支持用指定模板文件路径的方式来创建Template对象 >- 调用模板对象的render方法，并且传入一套context。返回一个基于模板的展现字符串，模板中的变量的标签会被context值替换 ``` $ python >>> from django import template >>> from django import settings >>> settings.configure() >>> t = template.Template('My name is {{ name }}.') >>> c = template.Context({'name': 'Adrian'}) >>> print t.render(c) My name is Adrian ``` **言归正传** 进入由django-admin startproject创建的mysite文件夹 ``` shiyanlou:mysite/ $ python manage.py shell ``` python manage.py shell，它将自动帮你处理DJANGO_SETTINGS_MODULE。在当前的这些示例中，我们鼓励你使用 python manage.py shell 这个方法，这样可以免去你大费周章地去配置那些你不熟悉的环境变量。 1. 创建模板对象 ``` >>> from django.template import Template >>> t = Template('My name is {{ name }}.') ``` 2.模板渲染 ```python >>> c = context({'name': 'marco'}) >>> t.render(c) u'My name is marco.' ``` t.render(c)返回的是一个Unicode对象，不是python字符串，'u'来区分。 Django对Unicode的支持 3.字典和Contexts ``` >>> from django.template import Template, Context >>> raw_template = """

Dear {{ person_name }},

... # """可以多行输入 ...

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,

\n\n

Thanks for placing an order from Outdoor Equipment. It's scheduled to\nship on April 2, 2009.

\n\n\n

You didn't order a warranty, so you're on your own when\nthe products inevitably stop working.

\n\n\n

Sincerely,
Outdoor Equipment

" ``` 第一行导入(import)类Template和Context，都在模块django.template中 16行把raw_template作为Template类构造函数的参数 18行创建一个Context对象c，Context构造的参数是字典数据类型。 22行Template的实例化对象t调用render()方法，传递context参数，渲染模板。 **使用Django模板系统的基本规则：写模板，创建 Template 对象，创建 Context ，调用 render() 方法。** ###5.3同一模板，多个上下文只进行一次模板创建然后多次调用render()方法渲染 **下面的对比Why？** ``` # 这是不好的写法 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})) ``` ###5.4 深度变量的查找每个python字符串都有upper()和isdigit()方法 ``` >>> from django.template import Template, Context >>> t = Template('{{ var }} -- {{ var.upper }} -- {{ var.isdigit }}') >>> t.render(Context({'var': 'hello'})) u'hello -- HELLO -- False' >>> t.render(Context({'var': '123'})) u'123 -- 123 -- True' ``` >句点查找规则可概括为当模板系统在变量名中遇到点时，按照以下顺序尝试进行查找： >>1.字典类型查找（比如 foo["bar"] ) >2.属性查找 (比如 foo.bar ) >3.方法调用（比如 foo.bar() ) >4.列表类型索引查找 (比如 foo[bar] ) 句点查找可以多级深度嵌套 ``` >>> from django.template import Template, Context >>> person = {'name': 'Sally', 'age': '43'} >>> t = Template('{{ person.name.upper }} is {{ person.age }} years old.') >>> c = Context({'person': person}) >>> t.render(c) u'SALLY is 43 years old.' ``` [1]: https://dn-anything-about-doc.qbox.me/django/2-4-1.png [2]: https://dn-anything-about-doc.qbox.me/django/5-1-1.png [3]: https://dn-anything-about-doc.qbox.me/django/5-1-2.png [4]: https://dn-anything-about-doc.qbox.me/django/3-2-1.png ![](https://dn-simplecloud.qbox.me/d7c28249d2731b228ce44df2d4578d18?watermark/1/image/aHR0cDovL3N5bC1zdGF0aWMucWluaXVkbi5jb20vaW1nL3dhdGVybWFyay5wbmc=/dissolve/60/gravity/SouthEast/dx/0/dy/10-wm) ![](https://dn-simplecloud.qbox.me/ab6c24f8ecc63d7143fda4c64a450d68?watermark/1/image/aHR0cDovL3N5bC1zdGF0aWMucWluaXVkbi5jb20vaW1nL3dhdGVybWFyay5wbmc=/dissolve/60/gravity/SouthEast/dx/0/dy/10-wm) ![](https://dn-simplecloud.qbox.me/5426b042d2d8624cfe7bfededaf254cc?watermark/1/image/aHR0cDovL3N5bC1zdGF0aWMucWluaXVkbi5jb20vaW1nL3dhdGVybWFyay5wbmc=/dissolve/60/gravity/SouthEast/dx/0/dy/10-wm)

“Python Django Web框架”实验报告