有关某些不同对象的相关名称在 Django 中不起作用

Question

I have trouble about calling related models. my models:

class Product(models.Model):
    product_model = models.CharField(max_length=255, default='')
    product_url = models.SlugField(max_length=200, default='')
    product_category = models.ForeignKey(Category,
        on_delete=models.CASCADE,
        default='',
        null=True,
        related_name="products",
    )
    product_subcategory = models.ForeignKey(Subcategory,
        on_delete=models.CASCADE,
        default='',
        null=True,
        related_name="products",
    )
    description = tinymce_models.HTMLField(verbose_name="text")
    product_img = models.ImageField(upload_to="product_imgs/" ,default='')

class Stock(models.Model):
    ONE = '1'
    TWO = '2'
    FREE = 'free'
    PRODUCT_SIZES = [
        (ONE, '1'),
        (TWO, '2'),
        (FREE, 'free'),
    ]
    size = models.CharField(max_length=60,default=" ", choices=PRODUCT_SIZES)
    quantity = models.PositiveIntegerField(default=0)
    price = models.FloatField(default=0, null=True)
    product = models.ForeignKey(Product, on_delete=models.CASCADE, related_name="pro")

each product can has 3 stock object with different sizes, I want show a product quantity in stock with all sizes, for example (size1 has 10, size2 has 10, sizefree has 10, I want show 30)

my views:

def products(request):
    if request.user.is_staff or request.user.is_superuser:
        products = Product.objects.all()
        ctx = {'products':products}
        return render(request, 'staff/products_list.html',ctx)       
    else:
        return redirect('/staff') 

and my html

                {% for product in products %}
                  <td class="text-info">
                    {% for product in product.pro.quantity.all %}
                      {{product}}
                    {% endfor %}
                  </td>
                {% endfor %}

how can I solve this problem ?

Answer 1

You have set related_name="pro" this means pro is a " Related Manager ". Hence writing product.pro.quantity does not make any sense. Instead you want to write something like product.pro.all and loop over it to get the related instances:

{% for product in products %}
    <td class="text-info">
        {% for stock in product.pro.all %}
            {{ stock.quantity }}
        {% endfor %}
    </td>
{% endfor %}

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Note : Furthermore pro does not make much sense as the related name here, even the default stock_set was a better related name here. Consider changing the related name to something more descriptive, example: stocks .