jinja2忽略取值None

Question

在jinja2的模板中取值{{a.b.c}},
如果a为None的话会跑错误：'None' has no attribute 'a',
能否配置为即使a为None了也能够继续执行下去，使得最后得到None或者其他空着都行。

Answer 1

继承Environment，重写getitem和getattr方法

from jinja2 import Environment
from jinja2.utils import Markup
from jinja2.runtime import Undefined
class ExEnvironment(Environment):
    def getitem(self, obj, argument):
        v = Environment.getitem(self, obj, argument)
        return None if isinstance(v, Undefined) else v
    def getattr(self, obj, attribute):
        v = Environment.getattr(self, obj, attribute)
        return None if isinstance(v, Undefined) else v
jinjaven = ExEnvironment()

后面用jinjaven去做渲染环境就行。

Answer 2

加个判断吧

{% if a%}{{a.b.c}}{%endif%}