### 經常使用的內置過濾器
**abs() ：返回參數的絕對值。**
```
{{-123?|?abs}} -> 123
```
**capitalize(*s*) ：首字母轉大寫**
```
{{?'airvip'|capitalize }} -> Airvip
```
**upper(s)：字母轉大寫**
```
{{?'airvip'|upper}} -> AIRVIP
```
**default(value,default_value=u'',boolean=False)：若果 value 為空，設置默認值**
```
{{?''|default('默認值',?true)?}} -> 默認值
{{?''|d('默認值',?true)?}} -> 默認值
```
**escape(s)：特殊符號正常顯示**
```
{{ '<airvip>'|e }}
-> <airvip>
{{ '<airvip>'|escape }} -> <airvip>
```
**first(seq)：返回序列的第一個元素**
```
{{?['airvip','python','lisy']|first?}} -> airvip
```
**join(value,d=u'',attribute=None)：將序列根據分割分連接**
```
{{ [1, 2, 3]|join('|') }} -> 1|2|3
```
**first(seq)：返回序列的最后一個元素**
```
{{?['airvip','python','lisy']|last}} -> lisy
```
**round(value, precision=0, method='common')**
```
{{ 42.55|round }} -> 43.0
{{ 42.55|round(1, 'floor') }} -> 42.5
```
**replace(s, old, new, count=None)**
```
{{ "Hello World"|replace("Hello", "Goodbye") }} -> Goodbye World
```
**random(seq)**
```
{{?['airvip','lisy','python']|random?}} -> 隨機出現 airvip 或者 lisy 或者 python
```
**length(object)**
```
{{?'airvip'|length?}} -> 6
{{?['airvip','lisy','python']|count?}} -> 3
```
**map()**
```
{{ [{'name':'airvip','age':24},{'name':'python','age':12},{'name':'lisy','age':18}]|map(attribute='name')|join(', ') }}
-> airvip, python, lisy
{{ [{'name':'airvip','age':24},{'name':'python','age':12},{'name':'lisy','age':18}]|map('upper')|join(', ') }}
-> {'NAME': 'AIRVIP', 'AGE': 24}, {'NAME': 'PYTHON', 'AGE': 12}, {'NAME': 'LISY', 'AGE': 18}
```
**reverse(value)**
```
{{?['airvip','python','lisy']|reverse|join(",")?}} -> lisy,python,airvip
```
**sort(value, reverse=False, case_sensitive=False, attribute=None)**
```
{{?['airvip','python','lisy']|sort|join(",")?}} ->airvip,lisy,python
{% for item in [{'name':'airvip','age':24},{'name':'python','age':12},{'name':'lisy','age':18}]|sort(attribute='age') %}
{{item.age}} --- {{item.name}}
{% endfor %}
-> 12 --- python 18 --- lisy 24 --- airvip
```
傳送門：[jinja2模板更多使用說明文檔](http://docs.jinkan.org/docs/jinja2/templates.html#builtin-filters)
