问Django模板: Threes中的分组项目

EN

class GroupPaintingsNode(template.Node):
    def __init__(self, num, varname):
        self.num, self.varname = int(num), varname

    def render(self, context):
        paintings = Painting.objects.all # do your fetching/filtering here.. 
        l = [[] for i in range(len(paintings))]
        i = 0
        while i < len(paintings):
            l[i].append([p.title for p in paintings[i:i+self.num]])
            l[i].append([p.desc for p in paintings[i:i+self.num]])
            i += self.num
        context[self.varname] = l
        return ''

def group_paintings(parser, token):
    tokens = token.contents.split()
    if len(tokens) != 4:
        raise template.TemplateSyntaxError, "'%s' tag requires three arguments" % tokens[0]
    if tokens[2] != 'as':
        raise template.TemplateSyntaxError, "Second argument to '%s' tag must be 'as'" % tokens[0]
    return GroupPaintingsNode(tokens[1], tokens[3])
group_paintings = register.tag(group_paintings)

{% group_paintings 3 as paintings %}
{% for p in paintings %}
    {% for title in p.0 %} {{ title }} {% endfor %}<br>
    {% for desc in p.1 %} {{ desc }} {% endfor %}
{% endfor %}

import itertools

from django import template

register = template.Library()

@register.filter
def chunks(value, chunk_length):
    """
    Breaks a list up into a list of lists of size <chunk_length>
    """
    clen = int(chunk_length)
    i = iter(value)
    while True:
        chunk = list(itertools.islice(i, clen))
        if chunk:
            yield chunk
        else:
            break

{% for chunk in paintings|chunks:3 %}
  <div class="row">
    {% for painting in chunk %}
      <div>{{ painting }}</div>
    {% endfor %}
  </div>
{% endfor %}

{% for p in paintingss %}
    <div class="painting">whatever</div>
    {% if forloop.counter|divisibleby:"3" %}
        <br>
    {% endif %}
{% endfor %}