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模型.py

class KEBReading(models.Model):
    #id = models.AutoField(primary_key=True,db_column='kr_id')
    date=models.DateField()
    time=models.TimeField()
    truepower_reading=models.DecimalField(max_digits=6,
    decimal_places=2,blank=False,null=False)
    apparentpower_reading=models.DecimalField(max_digits=6,
    decimal_places=2,blank=False,null=False)
    truepower_consumed=models.DecimalField(max_digits=6, decimal_places=2)
    voltage_reading=models.IntegerField(blank=False,null=False)
    powerfactor=models.DecimalField(max_digits=3,decimal_places=2)

表格.py

class KEBReading_form(forms.ModelForm):
    class Meta:
        model=KEBReading

        exclude=("truepower_consumed","powerfactor")
        widgets = {

               "date" : forms.widgets.DateInput(format="%d/%m/%Y"),
               "time" : forms.widgets.TimeInput(format="%H:%M")
               }

视图.py

def KEBReading1(request):
    if request.method == "POST":


        form = KEBReading_form(request.POST)
        if form.is_valid():
            prevdate=KEBReading.objects.latest("date")

            print prevdate.date
            print prevdate.time
        # q1 = KEBReading.objects.get(datetime.date.today()-datetime.timedelta(0))

            kr_truepower_reading = form.cleaned_data["truepower_reading"]
            kr_apparentpower_reading = form.cleaned_data["apparentpower_reading"]
            truepower_consumed1=kr_truepower_reading-prevdate.truepower_reading
            powerfactor1=kr_truepower_reading-                                           prevdate.truepower_reading/(kr_apparentpower_reading-prevdate.apparentpower_reading)


            form.save()
            KEBReading.objects.filter().values("date","time","truepower_reading",
            "apparentpower_reading","truepower_consumed","voltage","powerfactor")
            q2=KEBReading.objects.latest("date")

            context={'KEBReading_form':form,'q2':q2}
            return                  render_to_response('keb.html',context,context_instance=RequestContext(request))

        else:
            form = KEBReading_form()

            return render_to_response('keb.html',{'KEBReading_form':form},context_instance=RequestContext(request))

我想将 truepower_consumed aftr 计算保存在数据库中。但它给了我一个错误 truepower_consumed 列不能为空。我在表格中排除了 truepower_consumed。但在数据库中我需要保存该字段

4

2 回答 2

2

您需要保存表单commit=False并将适当的值分配给必填字段，然后再次保存对象。

例子：

def KEBReading1(request):
    if request.method == "POST":
    ....
    #your code till save
    obj = form.save(commit=False)
    #assing your values
    obj.truepower_consumed = truepower_consumed1
    obj.powerfactor = powerfactor1
    obj.save() #save

更多详细信息，请参阅使用表单上的字段子集

于 2013-01-22T06:30:13.387 回答
2

您应该使用form.save(commit=False)而不是form.save()然后计算剩下的两个字段。

请查看以下代码骨架：

## replace form.save() with following lines
obj = form.save(commit=False)
## Assign values to those 2 fields after calculation
## you can add a method on your model to do this
obj.calculate()

## those two values were assigned after call to calculate
## now you can save your obj
obj.save()


## Method to be added in your model
def calculate(self):
    ## Calculate truepower_consumed
    ## Calculate powerfactor
    self.truepower_consumed = <calculated truepower consumed>
    self.powerfactor = <calculated power factor>
于 2013-01-22T06:31:51.400 回答