python - 在 Jinja2 的子模板中访问父循环范围

Question

父类.txt

{% for dict in list_of_dictionaries %}
    {% block pick_dictionary_element %}
    {% endblock %}
{% endfor %}

child_one.txt

{% extends "parent.txt" %}
{% block pick_dictionary_element %}
    {{ dict.a }}
{% endblock %}

child_two.txt

{% extends "parent.txt" %}
{% block pick_dictionary_element %}
    {{ dict.b }}
{% endblock %}

然后:

from jinja2 import Template, Environment, FileSystemLoader
e = Environment(loader=FileSystemLoader("./"))
e.get_template("child_one.txt").render(list_of_dictionaries=[{'a': 'a', 'b': 'b'}])

产生空输出。如何从父 for 循环访问 dict var？我有点想像 jinja 只是内联 pick_dictionary_element 并且子项具有其父项的 for 循环范围？

Answer 1

您要执行的操作的关键是使用 scoped您街区的关键字:

{# parent.txt #}
{% for dict in list_of_dictionaries %}
    {% block pick_dictionary_element scoped %}
    {% endblock %}
{% endfor %}

为什么这很难调试？

你在循环中错误地使用了名称 dict:

{% for dict in list_of_dictionaries %}

这样做的副作用是子模板不会轻易提示，因为符号 dict 存在于它的上下文中。相反，如果你做了类似的事情:

{# parent.txt #}
{% for a_dict in list_of_dictionaries %}
    {% block pick_dictionary_element %}
    {% endblock %}
{% endfor %}

{# child_one.txt #}
{% extends "parent.txt" %}
{% block pick_dictionary_element %}
    {{ a_dict.a }}
{% endblock %}

你会被告知:

jinja2.exceptions.UndefinedError: 'a_dict' is undefined