在 Django 模板中聚合相关的整数字段值

Question

我有这个与节点模型相关的模型，

class Views(models.Model):
    related_tree = models.ForeignKey(Node, on_delete=models.CASCADE, blank=True, null=True, related_name='related_views')
    views_count = models.PositiveIntegerField(null=True, blank=True, default=0)
    user = models.ForeignKey(CustomUser, on_delete=models.CASCADE, blank=True, null=True)

    def __str__(self):
        return self.related_tree.name

在模板中，当我查询节点对象列表时，我想聚合每个对象的 'views_count' 的值。

我已经在我的模板中试过了

{% for tree in tree_result|slice:":14" %}
{% for view in tree.related_views.all %}

{{ view.views_count }}
{% endfor %}
{% endfor %}

我有当前树的所有相关 count_view 但我想做的是聚合相关字段的值并在 tree_result.[= 的 for 循环中显示它13=]

有什么建议吗？

编辑：

def ResultSearch(request, search):
    formatted_search = search.split('+$')
    filter = Q()
    cases = {}
    get_result_list = [x for x in search.split('+$') if x != '']
    for i, keyword in enumerate(get_result_list):
        filter |= Q(name__icontains=keyword)
        filter |= Q(Tags__icontains=keyword)
        cases['keyword_match_{}'.format(i)] = Case(
            When(name__icontains=keyword, then=1),
            default=Value(0),
            output_field=models.IntegerField(),
        )
    result = Node.objects.filter(
        filter,
        tree_type='root',
        published=True,
        tunisia_office=True
    ).annotate(
        **cases
    ).annotate(
        total_views=Sum('related_views__views_count'),
        num_bookmarks=Count('bookmarked_by'),
        keywords_matched=reduce(add, (F(name) for name in cases))
    ).order_by('-keywords_matched', '-num_bookmarks')

    context = {
    'searched_keyword': formatted_search,
    'result_list': result,
    }

Answer 1

您应该在视图中注释您的查询集，例如：

from django.db.models import Sum

Node.objects.annotate(
    <b>total_views=Sum('related_views__views_count')</b>
)

从这个查询集产生的 Node 将有一个额外的属性 .total_views，它是相关 Views.[=17 的 views_count 的总和=]

在您的模板中，您可以将其呈现为：

{% for tree in tree_result|slice:":14" %}
    {{ tree<b>.total_views</b> }}
{% endfor %}

Note: please do not aggregate in the template. Templates are not designed to implement business logic. A template should only contain "render logic". By using annotations, you will let the database do the aggregations. Databases are usually optimized to perform such tasks.

在 Django 模板中聚合相关的整数字段值

Aggregate related integer-field values in Django template

django

django-templates

django-related-manager