如何在python jinja模板中輸出loop.counter？

Question

我想能夠輸出當前循環迭代到我的模板。

根據文檔：http://wsgiarea.pocoo.org/jinja/docs/loops.html，有一個loop.counter變量，我試圖使用。

我有以下幾點：

<ul> 
{% for user in userlist %} 
    <li> 
     {{ user }} {{loop.counter}} 
    </li> 
     {% if loop.counter == 1 %} 
      This is the First user 
     {% endif %} 
{% endfor %} 
</ul> 

雖然沒有什麼是被輸出到我的模板。什麼是正確的語法？

Answer 1

循環中的計數器變量在jinja2中被稱爲loop.index。

>>> from jinja2 import Template 

>>> s = "{% for element in elements %}{{loop.index}} {% endfor %}" 
>>> Template(s).render(elements=["a", "b", "c", "d"]) 
1 2 3 4 

請參閱http://jinja.pocoo.org/docs/templates/瞭解更多信息。

Answer 2

在for循環塊中，您可以訪問一些特殊變量，包括loop.index - 但沒有loop.counter。從the official docs：

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. See the explanation below. 
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). 

Answer 3

此外，您還可以把標籤上的循環結構，你會得到你的櫃檯。

<ol> 
    {% for i in users %} 
     <li>ITEM</li> 
    {% endfor%} 
    </ol>