模型中的 Django 累积总和（sqlite）

Question

我的模型是：

class transaction(models.Model):
    transactiondate = models.DateField()
    category = models.ForeignKey(category, on_delete=models.PROTECT, default=0)
    details = models.CharField(max_length=200, null=True)
    amount = models.DecimalField(decimal_places=2, max_digits=10)
    accountid = models.ForeignKey(account, on_delete=models.PROTECT)

并且我使用原始 SQL 查询获得了每个日期的累计总数：

def cumulativebalance():
        query = """SELECT id, transactiondate,
            SUM("amount") 
            OVER (ORDER BY transactiondate) AS "cumsum" 
            FROM "transactions_transaction"
            GROUP BY transactiondate 
            ORDER BY transactiondate ASC, "cumsum" ASC
            """
        return balance = transaction.objects.raw(query)

这 return 我正在寻找的输出。我的问题是 Django 中是否有一种方法可以将其合并到我的模型中而不是将其作为原始 SQL?

我试过的

我确实找到了一个以前的并且我已经将答案修改为我自己的模型：

test = transaction.objects.annotate(
            cumsum=Func(
                Sum('amount'), 
                template='%(expressions)s OVER (ORDER BY %(order_by)s)', 
                order_by="transactiondate"
            ) 
        ).values('transactiondate', 'cumsum').order_by('transactiondate', 'cumsum')

但这给了我一个错误：“OVER”附近的 /transactions/ 处的 OperationalError：语法错误。我不明白这是在告诉我什么。

生成的SQL显示在回溯中。我最好的猜测是 OVER 之后应该是 PARTITION BY 而不是 ORDER BY，但我不知道如何从我的 python 代码中更改它。

('SELECT "transactions_transaction"."transactiondate", '
 'CAST(CAST(SUM("transactions_transaction"."amount") AS NUMERIC) OVER (ORDER '
 'BY transactiondate) AS NUMERIC) AS "cumsum" FROM "transactions_transaction" '
 'GROUP BY "transactions_transaction"."id", '
 '"transactions_transaction"."transactiondate", '
 '"transactions_transaction"."category_id", '
 '"transactions_transaction"."details", "transactions_transaction"."amount", '
 '"transactions_transaction"."accountid_id" ORDER BY '
 '"transactions_transaction"."transactiondate" ASC, "cumsum" ASC')

Answer 1

自 django-2.0, it is possible to work with a Window expressions [Django-doc]:

from django.db.models import F, Sum, <b>Window</b>

transaction.objects.annotate(
    cumsum=<b>Window(</b>Sum('amount'), order_by=F('transactiondate').asc()<b>)</b>
).order_by('transactiondate', 'cumsum')

由此产生的transaction对象会多出一个属性.cumsum。

Note: Models in Django are written in PascalCase, not snake_case, so you might want to rename the model from ~~transaction~~ to Transaction.

模型中的 Django 累积总和（sqlite）

Django cumulative sum in model (sqlite)

sqlite

django

我试过的