Question

我试图在DATABASE中创建一行，如果存在，则使用DJANGO将旧值更新为new + old。类似PHP的东西：

$sql= "IF EXISTS(SELECT * FROM April_sales WHERE label='".$product."') THEN
            BEGIN
            UPDATE francais SET sold=sold+'".$sold."'  WHERE label='".$product."';
            END;
            ELSE
            BEGIN
            INSERT INTO April_sales (sold,sold) VALUES('".$sold."','".$product."');
            END;
            END IF;";

我正在接收新行，尝试此操作：

query = April_sales.objects.get_or_create(product=product, sold= new_amount, date= timezone.now())
sum_value = query.sold + new_amount
query = April_sales(product=product, sold=sum_value , date=timezone.now()) 
query.save()

Answer 1

我找到了以下解决方案，它不漂亮而且有点长：如果有人有更好的建议，请随时改进。

try:
    query = April_sales.objects.get(product=product)
    query.sold = query.sold + new_amount
    query.date = timezone.now()
    query.save()
except April_sales.DoesNotExist:
    query = April_sales(product=product, sold=new_amount, date=timezone.now())
    query.save()

Answer 2

django的

get_or_create总是返回一个元组，你需要两个变量来捕捉你想要的东西：

试试这个：

query, created = April_sales.objects.get_or_create(product=product)
if created:
    query.sold = new_amount
else:
    query.sold += new_amount
query.date = timezone.now()
query.save()

update_or_create与Django一起用于旧行

2 个答案: