无法将新值分配给Django模型字段

Question

我有一个calculation = models.FloatField(default=0)字段，我正试图将新值（根据Debugger its 32）分配给它，如下所示：

   def calculate(**kwargs):
       row = ContractorScoring.objects.select_related('client', 'lead', 'budgetOptions', 'techCompatibility',
                                               'availableMen', 'degreeOfElaboration', 'geography',
                                               'nonInHouseReady', 'existingItPartner', 'httpsAvailability',
                                               'monthlyAdsBudget', 'mobilePageLoadSpeed', 'desktopPageLoadSpeed',
                                               'organicTraficTrend', 'payedTraficTrend', 'techStackEquality',
                                               'projectType', 'customerReadiness', 'servicesMeet')

       points_sum = float(row[0].budgetOptions.points + row[0].techCompatibility.points +
                   row[0].availableMen.points + row[0].degreeOfElaboration.points +
                   row[0].geography.points + row[0].nonInHouseReady.points +
                   row[0].existingItPartner.points + row[0].httpsAvailability.points +
                   row[0].monthlyAdsBudget.points + row[0].mobilePageLoadSpeed.points +
                   row[0].desktopPageLoadSpeed.points + row[0].organicTraficTrend.points +
                   row[0].payedTraficTrend.points + row[0].techStackEquality.points +
                   row[0].projectType.points + row[0].customerReadiness.points + row[0].servicesMeet.points)

       row[0].calculation = points_sum
       print(str(row[0].calculation))
       row[0].save(update_fields=['calculation'])

       return row[0].calculation

当我打印row[0].calculation值时，它会给我默认值0,0

你知道我做错了什么吗

Answer 1

您不应该修改仍在查询集中的模型实例（row[0]，其中row有点用词不当）

而是抓住对象本身：

def calculate(**kwargs):
    scoring = ContractorScoring.objects.select_related(...).first()
    points_sum = float(scoring.a + scoring.b + ...)
    scoring.calculation = points_sum
    scoring.save(update_fields=["calculation"])
    return scoring.calculation

请注意，您在ContractorScoring查询中缺少任何类型的过滤器，因此根本无法保证您将获得各种ContractorCoring的哪个对象！那可能不是你想要的