Question

我有一个基本模型，该模型被其他两个模型继承。如何在保持ProcurementRow关系不变的情况下将Tender对象更改为OfferRequest对象？我的目的是根据需要将投标转换为OfferRequest。

class Procurement(models.Model):
    pass

class ProcurementRow(models.Model)
    procurement = models.ForeignKey(Procurement)

class Tender(Procurement):
    pass

class OfferRequest(Procurement):
    pass

Answer 1

您可以遍历ClassCastException的字段，然后使用getattr / setattr复制这些字段。我还建议通过两者之间的Procurement建立牢固的关系，以便您可以跟踪事情的发生情况。

ForeignKeyField

Answer 2

我已经通过原始sql查询解决了我的问题。

def convert_procurement(request, procurement_id):
    procurement = get_object_or_404(Procurement, id=procurement_id).parent()
    from django.db import connection
    with connection.cursor() as cursor:
        if isinstance(procurement, Tender):
            cursor.execute("INSERT INTO procurement_offerrequest(procurement_ptr_id) VALUES (%s)", [procurement.id])
            cursor.execute("DELETE FROM procurement_tender WHERE procurement_ptr_id=(%s)", [procurement.id])
            return redirect('procurement:create_offer_request', procurement.id)
        elif isinstance(procurement, OfferRequest):
            cursor.execute("INSERT INTO procurement_tender(procurement_ptr_id) VALUES (%s)", [procurement.id])
            cursor.execute("DELETE FROM procurement_offerrequest WHERE procurement_ptr_id=(%s)", [procurement.id])

            return redirect('procurement:create_tender', procurement.id)

如何更改对象的子类

2 个答案: