Template syntax of filters and labels

filter:

Somewhat similar to a small filter method.

Features: will | The first argument of the left as a filter when the | current filter to the right of the second parameter

Filter (|)
(front-end code does not have to write you can write the backend passed to the front page at the front)
front and rear end unescaping
the front
| safe
back-end

views

def login(request):
    n = 123
    f = 12.12
    s = '你妹的 真难'
    l = [1,2,3,4,5,6]
    d = {'username':'jason','password':[123,222,444]}
    t = (1,2,3,4,5)
    se = {1,2,3,4}
    b = True
    ctime = datetime.now()
    file_size = 342384234234
    w = '奥术 大师件 大事肯德 基按 实际对 拉 螺栓空当接 龙'
    w1 = 'asdash ashd jkh sadas asdjjs had sjklad j a kjkjdsklas dkjsakldj dlsjakld '
    w2 = 'he llow ord wqe asdsad sadsadsa dsadasds adasds adsadsadsada sdsad'
    obj = MyClass()
    sss = "<h1>下午上课 一脸懵逼</h1>"
    sss1 = "<script>alert(123)</script>"
    sss2 = "<a href='http://www.xiaohuar.com'>下午上课 需要激情</a>"
    res = mark_safe(sss2)
    xo = '123213213'
    xo1 = 222
    yyy = {'user_list':[1,'22',{'username':['jason','egon']}]}
    return render(request,'login.html',locals())

html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<p>{{ file_size|filesizeformat }}</p>  <!--会自动帮你转化-->
<p>截取10个字符 三个点也算{{ w1|truncatechars:10 }}</p>
<p>截取10个字符 三个点也算{{ w|truncatechars:10 }}</p>
<p>安装空格截取单词 三个点不算{{ w1|truncatewords:6 }}</p>
<p>安装空格截取单词 三个点不算{{ w|truncatewords:6 }}</p>
<p>安装空格截取单词 三个点不算{{ w2|truncatewords:6 }}</p>

<p>{{ l|slice:'0:5' }}</p>  <!--切片 -->
<p>{{ l|slice:'0:5:2' }}</p>

<p>{{ ctime|date:'Y-m-d' }}</p> <!--日期-->
<p>{{ ctime|date:'Y年/m月' }}</p>


<p>{{ sss|safe }}</p> <!--使得后端传来的<h1>表现不会变成字符串-->
<p>{{ sss1|safe }}</p>
<p>{{ res }}</p>


<p>{{ xo|default:'' }} <!--有值就拿值 没值就用后面默认的-->
</body>
</html>

result:

318.9 GB

截取10个字符 三个点也算asdash ...

截取10个字符 三个点也算奥术 大师件 ...

安装空格截取单词 三个点不算asdash ashd jkh sadas asdjjs had ...

安装空格截取单词 三个点不算奥术 大师件 大事肯德 基按 实际对 拉 ...

安装空格截取单词 三个点不算he llow ord wqe asdsad sadsadsa ...

[1, 2, 3, 4, 5]

[1, 3, 5]

2019-10-23

2019年/10月

下午上课 一脸懵逼（其实很大，只是这里显示不出来，他是<h1>标签）
下午上课 需要激情

123213213

Template grammar symbols on two kinds of
relevant variables {} {}
{} Logical associated %%

label

html

{% for foo in l %}
    <p>{{ forloop }}</p>
{% endfor %}

This forloop it comes inside

Print out the contents of such

{'parentloop': {}, 'counter0': 0, 'counter': 1, 'revcounter': 6, 'revcounter0': 5, 'first': True, 'last': False}

{'parentloop': {}, 'counter0': 1, 'counter': 2, 'revcounter': 5, 'revcounter0': 4, 'first': False, 'last': False}

{'parentloop': {}, 'counter0': 2, 'counter': 3, 'revcounter': 4, 'revcounter0': 3, 'first': False, 'last': False}

{'parentloop': {}, 'counter0': 3, 'counter': 4, 'revcounter': 3, 'revcounter0': 2, 'first': False, 'last': False}

{'parentloop': {}, 'counter0': 4, 'counter': 5, 'revcounter': 2, 'revcounter0': 1, 'first': False, 'last': False}

{'parentloop': {}, 'counter0': 5, 'counter': 6, 'revcounter': 1, 'revcounter0': 0, 'first': False, 'last': True}

You can see the value of counter0 and counter1 growing, starting with 0 and 1 until 5 and 6, first only the first cycle when the guess is True, last and only time in the last cycle will be True.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

{% for foo in l %}
    <p>{{ forloop }}</p>
    {% if forloop.first %}
        <p>这是我的第一次</p>
    {% elif forloop.last %}
        <p>这是最后一次了啊</p>
    {% else %}
        <p>嗨起来 大宝贝~</p>
    {% endif %}
{% endfor %}


{% for foo in xo %}
    <p>{{ forloop.counter }}:{{ foo }}</p> <!--这里的‘：’只是一个普通的字符-->
    {% empty %} <!--在xo是空的时候才会走，才能走下面那一句-->
    <p>你给我的对象是个空的没法进行for循环</p>
{% endfor %}


{% for foo in d.items %}
    <p>{{ foo }}</p>
{% endfor %}

{% for foo in d.keys %}
    <p>{{ foo }}</p>
{% endfor %}

{% for foo in d.values %}
    <p>{{ foo }}</p>
{% endfor %}
</body>
</html>

result:

这是我的第一次

嗨起来 大宝贝~

嗨起来 大宝贝~

嗨起来 大宝贝~

嗨起来 大宝贝~

这是最后一次了啊

1:1

2:2

3:3

4:2

5:1

6:3

7:2

8:1

9:3

('username', 'jason')

('password', [123, 222, 444])

username

password

jason

[123, 222, 444]

Custom filters and labels

Step:
1 In the application name below to create a new templatetags folder (must be that name)
2 to create a new name in any change folder py file
3 fixed to write two lines of code in the py file
from django.template import Library

Then py files in your new templatetags file can create a custom filter

such as:

from django.template import Library

register = Library()

@register.filter(name='myplus')
def index(a,b):
    return a+b

Then you can call up at the front, called by

{% load my_tag %} #固定写法，你新建的py文件叫什么，这里就写什么
{{ 123|myplus:123}}

result:

Similarly, a custom label is written in the same position

@register.simple_tag(name='mysm')
def login(a,b,c,d):
    return '%s/%s/%s/%s'%(a,b,c,d)

Invocation:

{% load my_tag %}
{% mysm 1 2 3 4 %}

result:

1/2/3/4

区别 标签不能再if中使用
            {% if 0|myplus:123 %}  可以用
                <p>有值</p>
            {% endif %}


            {% if mysm 1 2 3 4 %}  不能用
                <p>有值</p>
            {% endif %}