我希望能够将当前循环迭代输出到我的模板。
根据文件，有个循环。计数器变量，我试图使用:
<ul>
{% for user in userlist %}
<li>
{{ user }} {{loop.counter}}
</li>
{% if loop.counter == 1 %}
This is the First user
{% endif %}
{% endfor %}
</ul>
而是被输出到我的模板中。正确的语法是什么?
循环内部的计数器变量称为循环。Jinja2索引。
>>> from jinja2 import Template
>>> s = "{% for element in elements %}{{loop.index}} {% endfor %}"
>>> Template(s).render(elements=["a", "b", "c", "d"])
1 2 3 4
除了循环。指数，也有
循环。Index0(从0开始的索引) 循环。Revindex(反向索引;结束于1) 循环。Revindex0(反向索引;结束于0) 更多信息请访问http://jinja.pocoo.org/docs/templates/。
在for-loop块内部，您可以访问一些特殊的变量，例如loop。索引(但不是loop.counter)。官方文件显示:
| Variable | Description |
|---|---|
loop.index |
The current iteration of the loop. (1 indexed) |
loop.index0 |
The current iteration of the loop. (0 indexed) |
loop.revindex |
The number of iterations from the end of the loop (1 indexed) |
loop.revindex0 |
The number of iterations from the end of the loop (0 indexed) |
loop.first |
True if first iteration. |
loop.last |
True if last iteration. |
loop.length |
The number of items in the sequence. |
loop.cycle |
A helper function to cycle between a list of sequences. |
loop.depth |
Indicates how deep in a recursive loop the rendering currently is. Starts at level 1 |
loop.depth0 |
Indicates how deep in a recursive loop the rendering currently is. Starts at level 0 |
loop.previtem |
The item from the previous iteration of the loop. Undefined during the first iteration. |
loop.nextitem |
The item from the following iteration of the loop. Undefined during the last iteration. |
loop.changed(*val) |
True if previously called with a different value (or not called at all). |
如果你正在使用Django，请使用forloop。用Counter代替loop.counter:
<ul>
{% for user in userlist %}
<li>
{{ user }} {{forloop.counter}}
</li>
{% if forloop.counter == 1 %}
This is the First user
{% endif %}
{% endfor %}
</ul>
在Python代码中:
env = Environment(loader=FileSystemLoader("templates"))
env.globals["enumerate"] = enumerate
在模板中:
{% for idx, val in enumerate(list) %}
{{ idx }}. {{val}}
{% endfor %}
现实生活中的例子:
{% for image in item['images'] %}
{% set image_id = item_id ~ '-preview-' ~ loop.index0 %}
<div id="{{ image_id }}" class="overlay">
<a class="cancel" href="#{{ item_id }}"></a>
<div class="popup">
{% set src = image if image.startswith('http') else '/static/images/store/' ~ item_id ~ '/' ~ image %}
<a href="{{ src }}"><img class="modal-img" src="{{ src }}"/></a>
</div>
</div>
{% endfor %}
