Snippet: Django Columns Filter
I was looking around for an easy way to split lists of items into columns in a way that the number of items in each column would be less than or equal to the number of items in the first column. This prevents a final column with several more items than the others.
I came across an old post from Annie Mullin that established a templatetag to do this using a generator. I liked the idea, but felt that a templatetag was too unwieldy - a filter would be simpler and easier to use in a template. So, I turned it into one:
@register.filter def columns(lst, cols): """ Break a list into ``n`` lists, typically for use in columns. >>> lst = range(10) >>> for list in columns(lst, 3): ... list [0, 1, 2, 3] [4, 5, 6] [7, 8, 9] """ try: cols = int(cols) lst = list(lst) except (ValueError, TypeError): raise StopIteration() start = 0 for i in xrange(cols): stop = start + len(lst[i::cols]) yield lst[start:stop] start = stop
This is then used in a template like this:
{% for column in list|columns:"3" %} <ul> {% for item in column %} <li> <a href="{{ item.get_absolute_url }}">{{ item }}</a> </li> {% endfor %} </ul> {% endfor %}
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Brandon Konkle
I've been creating websites for over 10 years, and I've been using Django since early 2008. I focus on high quality, well-tested, maintainable code and reliable high-performance deployments. Web development is something that I am very excited about, and I love finding elegant and innovative ways to push web applications further.
