使用Django haystack多值字段迭代搜索结果视图中的项

如果我的一个搜索索引上有一个多值字段,并且我想在搜索结果中显示每个值,我该如何做?似乎有些东西的格式不合适,或者我不知怎么误解了多值字段?

class PageAttachmentIndex(indexes.SearchIndex):
    # This should reference search/indexes/pages/pageattachment_text.txt
    text      = indexes.CharField(document=True, use_template=True)
    title     = indexes.CharField(model_attr='name')
    page      = indexes.IntegerField(model_attr='page_id')
    attrs     = indexes.MultiValueField()
    file      = indexes.CharField(model_attr='file')
    filesize  = indexes.IntegerField(model_attr='file__size')
    timestamp = indexes.DateTimeField(model_attr='timestamp')
    url       = indexes.CharField(model_attr='page')

    def prepare_attrs(self, obj):
        """ Prepare the attributes for any file attachments on the
            current page as specified in the M2M relationship. """
        # Add in attributes (assuming there's a M2M relationship to
        # attachment attributes on the model.) Note that this will NOT
        # get picked up by the automatic schema tools provided by haystack
        attributes = obj.attributes.all()
        return attributes

在我的模板视图中利用此功能:

    {% if result.attrs|length %}
    <div class="attributes">
        <ul>
        {% for a in result.attrs %}
            <li class="{% cycle "clear" "" "" %}"><span class="name">{{ a.name }}</span>: <span class="value">{{ a.value }}</span></li>
        {% endfor %}
        </ul>
        <div class="clear"></div>
    </div>
    {% endif %}

这对我来说似乎什么都没有:(