我可以从注释中的销售表中获取 Sum(amount_sold) 的值吗?

Question

>我正在尝试显示一个用数据库中的总和值填充的 html 表。我有sum_amount_purchased，sum_total_price_purchased工作正常，但我正在努力sum_amount_sold获得我需要查询销售表的这个值。是否可以在注释中执行此操作？我想要该用户的每种货币的所有销售额的总和。任何建议将不胜感激。

下表

{% for transaction in transactions %}
    <tr>
        <td>{{transaction.currency}}</td>
        <td>{{transaction.sum_amount_purchased}}</td>
        <td>{{transaction.sum_total_price_purchased }}</td>
        <td>{{transaction.sum_amount_sold}}</td>
    </tr>
{% endfor %}

交易模式如下

class Transaction(models.Model):
    currency = models.CharField(max_length=20)
    amount = models.IntegerField()
    total_price = models.DecimalField(max_digits=8, decimal_places=2)
    date_purchased = models.DateTimeField()
    note = models.TextField(default="")
    owner = models.ForeignKey(User, on_delete=models.CASCADE)
    amount_per_coin = models.DecimalField(max_digits=8, decimal_places=2, editable=False)

    def save(self, *args, **kwargs):
        self.amount_per_coin = self.total_price / self.amount
        super(Transaction, self).save(*args, **kwargs)
    def __str__(self):
        return str(self.pk)+','+self.currency + ', '+str(self.amount)
    def get_absolute_url(self):
        return reverse('transaction-detail', kwargs={'pk': self.pk})

销售模式如下

class Sale(models.Model):
    amount_sold = models.IntegerField()
    total_price_sold = models.DecimalField(max_digits=8, decimal_places=2)
    date_sold = models.DateTimeField(default=timezone.now)
    note = models.TextField(default="")
    transaction = models.ForeignKey(Transaction, on_delete=models.CASCADE, related_name="sales")
    amount_per_coin_sold = models.DecimalField(max_digits=8, decimal_places=2, editable=False)
    def __str__(self):
        return str(self.pk)+','+str(self.amount_sold) + ', '+self.note
    def save(self, *args, **kwargs):
        self.amount_per_coin_sold = self.total_price_sold / self.amount_sold
        super(Sale, self).save(*args, **kwargs)
    def get_absolute_url(self):
        return reverse('sale-detail', kwargs={'pk': self.pk})

查看下文

@login_required
def portfolio(request):
    context = {
        'transactions': Transaction.objects.filter(owner=request.user).values('currency').annotate(
            sum_amount_purchased=Sum('amount'),
            sum_total_price_purchased=Sum('total_price'),
            sum_amount_sold=Sum('sales')
        ),
    }
    return render(request, 'webapp/portfolio.html', context, {'title': 'Portfolio'})

Answer 1

您需要使用双下划线语法遍历到您实际想要求和的 Sale 字段 - 大概amount_sold：

sum_amount_sold=Sum('sales__amoint_sold')