Python - Django - 模板语言之 Filters（过滤器）
通过管道符 "|" 来使用过滤器，{{ value|过滤器:参数 }}
Django 的模板语言中提供了六十个左右的内置过滤器
urls.py：
from django.conf.urls import url
from django.contrib import admin
from app01 import views
urlpatterns = [
url(r'^filter_test/', views.filter_test),
]
default：
如果一个变量的变量名不存在或者没有给其传值，可以通过 default 使用默认值
views.py：
from django.shortcuts import render, redirect, HttpResponse
from app01 import models
# Filter 测试
def filter_test(request):
name = "Jack"
age = 18
return render(
request,
"filter_test.html",
{
"name": name,
"age": None,
})
这里的 age 变量传了一个空值
filter_test.html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Filter 测试</title>
</head>
<body>
<h1>Filter 测试页面</h1>
<!-- default -->
{{ name }}
<br>
{{ name1|default:"这里不存在" }}
<br>
{{ age|default:"这里也不存在" }}
</body>
</html>
name1 是没有定义的变量
运行效果：
注意：
这里不能带有空格
length：
返回字符串或列表的长度
views.py：
from django.shortcuts import render, redirect, HttpResponse
from app01 import models
# Filter 测试
def filter_test(request):
name = "Jack"
age = 18
hobby = ["Reading", "Basketball", "Movie", "Music"]
return render(
request,
"filter_test.html",
{
"name": name,
"age": None,
"hobby_list": hobby,
})
filter_test.html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Filter 测试</title>
</head>
<body>
<h1>Filter 测试页面</h1>
<!-- default -->
{{ name }}
<br>
{{ name1|default:"这里不存在" }}
<br>
{{ age|default:"这里也不存在" }}
<br>
<!-- length -->
{{ name|length }}
<br>
{{ hobby_list|length }}
<br>
{{ age|length }}
</body>
</html>
运行效果：
这里计算了 name 变量值、hobby_list 列表、age 空值的长度
slice：
slice 是用来进行切片的
views.py：
from django.shortcuts import render, redirect, HttpResponse
from app01 import models
# Filter 测试
def filter_test(request):
name = "Jack"
age = 18
hobby = ["Reading", "Basketball", "Movie", "Music"]
return render(
request,
"filter_test.html",
{
"name": name,
"age": None,
"hobby_list": hobby,
})
filter_test.html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Filter 测试</title>
</head>
<body>
<h1>Filter 测试页面</h1>
<!-- default -->
{{ name }}
<br>
{{ name1|default:"这里不存在" }}
<br>
{{ age|default:"这里也不存在" }}
<br>
<!-- length -->
{{ name|length }}
<br>
{{ hobby_list|length }}
<br>
{{ age|length }}
<br>
<!-- 切片 -->
{{ hobby_list|slice:"0:2" }}
<br>
{{ name|slice:"0:2" }}
</body>
</html>
运行效果：
filesizeformat：
将一串数字格式化成文件格式
views.py：
from django.shortcuts import render, redirect, HttpResponse
from app01 import models
# Filter 测试
def filter_test(request):
name = "Jack"
age = 18
file_size = 988222836293733
hobby = ["Reading", "Basketball", "Movie", "Music"]
return render(
request,
"filter_test.html",
{
"name": name,
"age": None,
"hobby_list": hobby,
"filesize": file_size,
})
filter_test.html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Filter 测试</title>
</head>
<body>
<h1>Filter 测试页面</h1>
<!-- default -->
{{ name }}
<br>
{{ name1|default:"这里不存在" }}
<br>
{{ age|default:"这里也不存在" }}
<br>
<!-- length -->
{{ name|length }}
<br>
{{ hobby_list|length }}
<br>
{{ age|length }}
<br>
<!-- 切片 -->
{{ hobby_list|slice:"0:2" }}
<br>
{{ name|slice:"0:2" }}
<br>
<!-- filesizeformat -->
{{ filesize|filesizeformat }}
</body>
</html>
运行结果：
这里会根据大小格式化成 KB，MB，GB 和 TB
cut：
删除字符串或列表中和过滤器参数相同的内容
views.py：
from django.shortcuts import render, redirect, HttpResponse
from app01 import models
# Filter 测试
def filter_test(request):
name = "Jack"
age = 18
file_size = 988222836293733
hobby = ["Reading", "Basketball", "Movie", "Music"]
return render(
request,
"filter_test.html",
{
"name": name,
"age": None,
"hobby_list": hobby,
"filesize": file_size,
})
filter_test.html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Filter 测试</title>
</head>
<body>
<h1>Filter 测试页面</h1>
<!-- default -->
{{ name }}
<br>
{{ name1|default:"这里不存在" }}
<br>
{{ age|default:"这里也不存在" }}
<br>
<!-- length -->
{{ name|length }}
<br>
{{ hobby_list|length }}
<br>
{{ age|length }}
<br>
<!-- 切片 -->
{{ hobby_list|slice:"0:2" }}
<br>
{{ name|slice:"0:2" }}
<br>
<!-- filesizeformat -->
{{ filesize|filesizeformat }}
<br>
<!-- cut -->
{{ name|cut:"ac" }}
<br>
{{ hobby_list|cut:"Movie" }}
</body>
</html>
运行结果：
Jack 被删除了 ac，hobby_list 列表被删除了 Movie
join：
连接字符串
views.py：
from django.shortcuts import render, redirect, HttpResponse
from app01 import models
# Filter 测试
def filter_test(request):
name = "Jack"
age = 18
file_size = 988222836293733
hobby = ["Reading", "Basketball", "Movie", "Music"]
return render(
request,
"filter_test.html",
{
"name": name,
"age": None,
"hobby_list": hobby,
"filesize": file_size,
})
filter_test.html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Filter 测试</title>
</head>
<body>
<h1>Filter 测试页面</h1>
<!-- default -->
{{ name }}
<br>
{{ name1|default:"这里不存在" }}
<br>
{{ age|default:"这里也不存在" }}
<br>
<!-- length -->
{{ name|length }}
<br>
{{ hobby_list|length }}
<br>
{{ age|length }}
<br>
<!-- 切片 -->
{{ hobby_list|slice:"0:2" }}
<br>
{{ name|slice:"0:2" }}
<br>
<!-- filesizeformat -->
{{ filesize|filesizeformat }}
<br>
<!-- cut -->
{{ name|cut:"ac" }}
<br>
{{ hobby_list|cut:"Movie" }}
<br>
<!-- join -->
{{ name|join:"+" }}
<br>
{{ hobby_list|join:"-" }}
</body>
</html>
运行结果：
safe：
Django 模板会自动对 html、js 标签进行转义，safe 可以让 Django 不对标签进行转义
views.py：
from django.shortcuts import render, redirect, HttpResponse
from app01 import models
# Filter 测试
def filter_test(request):
name = "Jack"
age = 18
file_size = 988222836293733
test_html = "<a href='www.baidu.com'>这是一个 html 标签</a>"
hobby = ["Reading", "Basketball", "Movie", "Music"]
return render(
request,
"filter_test.html",
{
"name": name,
"age": None,
"hobby_list": hobby,
"filesize": file_size,
"test_html": test_html,
})
filter_test.html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Filter 测试</title>
</head>
<body>
<h1>Filter 测试页面</h1>
<!-- default -->
{{ name }}
<br>
{{ name1|default:"这里不存在" }}
<br>
{{ age|default:"这里也不存在" }}
<br>
<!-- length -->
{{ name|length }}
<br>
{{ hobby_list|length }}
<br>
{{ age|length }}
<br>
<!-- 切片 -->
{{ hobby_list|slice:"0:2" }}
<br>
{{ name|slice:"0:2" }}
<br>
<!-- filesizeformat -->
{{ filesize|filesizeformat }}
<br>
<!-- cut -->
{{ name|cut:"ac" }}
<br>
{{ hobby_list|cut:"Movie" }}
<br>
<!-- join -->
{{ name|join:"+" }}
<br>
{{ hobby_list|join:"-" }}
<br>
<!-- safe -->
{{ test_html }}
<br>
{{ test_html|safe }}
</body>
</html>
运行效果：
没加 safe 的话就被 Django 默认转义了，加了 safe，a 标签就没被转义
truncatechars：
通过参数指定截断字符数，将多于指定的字符数的字符串字符进行截断，被截断的内容用 “...” 来代替
views.py:
from django.shortcuts import render, redirect, HttpResponse
from app01 import models
# Filter 测试
def filter_test(request):
name = "Jack"
age = 18
file_size = 988222836293733
test_html = "<a href='www.baidu.com'>这是一个 html 标签</a>"
hobby = ["Reading", "Basketball", "Movie", "Music"]
text = "abcdefghijklmnopqrstuvwxyz"
return render(
request,
"filter_test.html",
{
"name": name,
"age": None,
"hobby_list": hobby,
"filesize": file_size,
"test_html": test_html,
"text": text,
})
filter_test.html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Filter 测试</title>
</head>
<body>
<h1>Filter 测试页面</h1>
<!-- default -->
{{ name }}
<br>
{{ name1|default:"这里不存在" }}
<br>
{{ age|default:"这里也不存在" }}
<br>
<!-- length -->
{{ name|length }}
<br>
{{ hobby_list|length }}
<br>
{{ age|length }}
<br>
<!-- 切片 -->
{{ hobby_list|slice:"0:2" }}
<br>
{{ name|slice:"0:2" }}
<br>
<!-- filesizeformat -->
{{ filesize|filesizeformat }}
<br>
<!-- cut -->
{{ name|cut:"ac" }}
<br>
{{ hobby_list|cut:"Movie" }}
<br>
<!-- join -->
{{ name|join:"+" }}
<br>
{{ hobby_list|join:"-" }}
<br>
<!-- safe -->
{{ test_html }}
<br>
{{ test_html|safe }}
<br>
<!-- truncatechars -->
{{ text|truncatechars:10 }}
</body>
</html>
运行结果：
date：
对时间进行格式化
views.py：
from django.shortcuts import render, redirect, HttpResponse
from app01 import models
import datetime
# Filter 测试
def filter_test(request):
name = "Jack"
age = 18
file_size = 988222836293733
test_html = "<a href='www.baidu.com'>这是一个 html 标签</a>"
hobby = ["Reading", "Basketball", "Movie", "Music"]
text = "abcdefghijklmnopqrstuvwxyz"
now_time = datetime.datetime.now()
return render(
request,
"filter_test.html",
{
"name": name,
"age": None,
"hobby_list": hobby,
"filesize": file_size,
"test_html": test_html,
"text": text,
"now_time": now_time,
})
filter_test.html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Filter 测试</title>
</head>
<body>
<h1>Filter 测试页面</h1>
<!-- default -->
{{ name }}
<br>
{{ name1|default:"这里不存在" }}
<br>
{{ age|default:"这里也不存在" }}
<br>
<!-- length -->
{{ name|length }}
<br>
{{ hobby_list|length }}
<br>
{{ age|length }}
<br>
<!-- 切片 -->
{{ hobby_list|slice:"0:2" }}
<br>
{{ name|slice:"0:2" }}
<br>
<!-- filesizeformat -->
{{ filesize|filesizeformat }}
<br>
<!-- cut -->
{{ name|cut:"ac" }}
<br>
{{ hobby_list|cut:"Movie" }}
<br>
<!-- join -->
{{ name|join:"+" }}
<br>
{{ hobby_list|join:"-" }}
<br>
<!-- safe -->
{{ test_html }}
<br>
{{ test_html|safe }}
<br>
<!-- truncatechars -->
{{ text|truncatechars:10 }}
<br>
<!-- 时间 -->
{{ now_time|date:"Y-m-d H:i:s"}}
</body>
</html>
运行结果：
