在基于 Django 类的视图中使用反向关系

Question

我有一个 django 模型如下：

class Category(models.Model):
    category_name = models.CharField(max_length=250, blank=True, null=True)

    class Meta:
        verbose_name = "Category"
        verbose_name_plural = "Categories"

    def __unicode__(self):
        return self.category_name

class Product(models.Model):
    category = models.ForeignKey(Category)
    model_name = models.CharField(max_length=255, blank=True, null=True)

    class Meta:
        verbose_name = "Product"
        verbose_name_plural = "Products"

    def __unicode__(self):
        return self.model_name

在我看来，我有一个 ListView 如下：

class CategoryList(ListView):
    model = Category
    template_name = 'categories.html'

而我的categories.html如下：

{% extends "base.html" %}

{% block content %}
    <div>
        <h2>Categories</h2>

        {% for category in object_list %}
        <div class="panel-group" id="accordion" role="tablist" aria-multiselectable="true">
            <div class="panel panel-default">
                <div class="panel-heading" role="tab" id="h{{category.id}}">
                    <h4 class="panel-title">
                        <a class="collapsed" data-toggle="collapse" data-parent="#accordion" href="#{{category.id}}" aria-expanded="true" aria-controls="{{category.id}}">
                          {{category.category_name}}
                        </a>
                    </h4>
                </div>
                <div id="{{category.id}}" class="panel-collapse collapse" role="tabpanel" aria-labelledby="h{{category.id}}">
                    <div class="panel-body">
                        {{category.category_name}} //trying to change here by displaying all model_names!!
                    </div>
                </div>
            </div>
        </div>
        {% endfor %}
{% endblock %}

现在我正在尝试在模板（即面板正文中）的手风琴内显示一个类别中所有可用产品的列表。如何更改视图以访问这些反向关系？对基于类的视图还很陌生？

Answer 1

您可以使用相关领域经理products_set访问每个类别的相关产品，例如：

{{category.category_name}} //trying to change here by displaying all model_names!!
<ul>
{% for product in category.product_set.all %}
  <li>{{ product.model_name }}</li>
{% endfor %}
</ul>

如果您需要更复杂的过滤，您可以在视图中执行此操作或编写自定义模板标记。在视图中执行它看起来像这样：

class CategoryList(ListView):
    model = Category
    template_name = 'categories.html'

    def get_queryset(self):
        qs = super(CategoryList, self).get_queryset()
        for category in qs:
            category.some_filtered_products = category.product_set.filter(...)
        return qs

这将在查看期间解析查询集，并将过滤后的产品放入每个 Category 实例上的新内存属性中。