python - 如何解决没有函数与给定名称和参数类型匹配的问题。您可能需要添加显式类型转换

Question

already_transferred = Transfer.objects.all().filter(transferred_by=request.user, account_id=id).aggregate(total=Coalesce(Sum('amount'), 0))

服务器给出了这个错误

function sum(text) does not exist
LINE 1: SELECT COALESCE(SUM("API_insidetransfer"."amount"), 0) AS "a...
                        ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.

这是我的模型

class Transfer(models.Model):
    transferred_by = models.CharField(max_length=120)
    account_id = models.CharField(max_length=120)
    amount = models.CharField(max_length=120, default=0)
    created_on = models.DateTimeField(auto_now=True)

我该如何解决这个问题？

Answer 1

问题是您的amount是一个CharField。你不能对charfields求和。例如，'foo' 和 'bar' 的总和是多少。

因此，您应该在模型级别解决问题:将 amount 设为 DecimalField(或 IntegerField)。例如:

class Transfer(models.Model):
    transferred_by = models.CharField(max_length=120)
    account_id = models.CharField(max_length=120)
    amount = <b>modelsDecimalField(max_digits=12, decimal_places=2, default=0)</b>
    created_on = models.DateTimeField(auto_now=True)