Using getattr in Jinja2 gives me an error (jinja2.exceptions.UndefinedError: 'getattr' is undefined)

问题

With regular python, I could get getattr(object, att) but in Jinja2, I get:

jinja2.exceptions.UndefinedError
jinja2.exceptions.UndefinedError: 'getattr' is undefined

How can I use it?

回答1:

Jinja2 is not Python. It uses a Python-like syntax, but does not define the same built-in functions.

Use subscription syntax instead; you can use attribute and subscription access interchangeably in Jinja2:

{{ object[att] }}

or you can use the attr() filter:

{{ object|attr(att) }}

From the Variables section of the template designer documentation:

You can use a dot (.) to access attributes of a variable in addition to the standard Python __getitem__ “subscript” syntax ([]).

The following lines do the same thing:

{{ foo.bar }}
{{ foo['bar'] }}

and further down in the same section, explaining the implementation details:

foo['bar'] works mostly the same with a small difference in sequence:

• check for an item 'bar' in foo. (foo.__getitem__('bar'))
• if there is not, check for an attribute called bar on foo. (getattr(foo, 'bar'))
• if there is not, return an undefined object.

来源：https://stackoverflow.com/questions/35407008/using-getattr-in-jinja2-gives-me-an-error-jinja2-exceptions-undefinederror-ge