使用modelchoicefield时Django无效的形式

Question

我是 Django 新手，我一直在努力在我的观点中获得 forms.ModelChoiceField 的选定值。我的表单（帖子）无效，我注意到 request.POST 返回了 ModelChoiceField 中的所有可能值。如何仅获取用户选择的模型？提前感谢您的帮助。

型号

我有一个传感器模型和一个测量模型...

class Sensor(models.Model):
    # This contains information about a sensor, type, location, and other
    type = models.CharField(max_length=16)
    ...

class Measurement(models.Model):
    #This contains the measurements of the sensors at a given date
    sensor = models.ForeignKey('Sensor')
    date = models.DateField()
    temperature = models.FloatField()
    pressure = models.FloatField()
    ...
    class Meta:
        unique_together = ('sensor', 'date')

表格

...以及允许用户选择传感器和日期的表单：

class MeasurementForm(forms.ModelForm):
    #the user is allowed to choose any sensor that is related to the measurement table
    sensor = forms.ModelChoiceField(queryset=Sensor.objects.exclude(measurement=None))
    date =  forms.DateField(widget=DateInput(attrs={'format':'%Y-%m-%d'}), initial=datetime.today)

到目前为止一切顺利，这由 get 方法呈现，用户可以选择传感器和日期。但是，提交后，以下视图在帖子中失败：

观看次数

class MeasurementView(View):
    form_class = MeasurementForm
    my_template = "measurement.html"

    def get(self, request, *args, **kwargs):
        form = self.form_class()
        return render(request, self.my_template, {'form': form, 'data':None})

    def post(self, request, *args, **kwargs):
        print(request.POST)
        print(new_form.errors)
        new_form = self.form_class(data=request.POST)
        if new_form.is_valid():
            print('form is valid')
            data = get_data_for_sensor_date(
                        new_form.cleaned_data['sensor'],
                        new_form.cleaned_data['date']))
            return render(request, self.my_template, {'form':new_form, 'data':data})
        else:
            return render(request, self.my_template, {'form':new_form, 'data':None})

控制台输出

<QueryDict: {'sensor': ['', '1'], 
             'csrfmiddlewaretoken': ['YUPfrdhdbQdAa7EyNx2sJeHdbxmQXTTW'], 
             'date': ['2016-11-07']}>

<ul class="errorlist">
  <li>__all__
    <ul class="errorlist nonfield">
      <li>Measurement with this Sensor and Date already exists.
      </li>
    </ul>
  </li>
</ul>

Answer 1

我找到了这个链接Django formview returns object already exists error with a modelform

我引用的内容： “好的。我找到了我的错误的解决方案。导致模型已存在错误的原因是我的 ModelForm CheckProductForm。代号属性是唯一的，所以我的验证总是返回 False。我所做的就是将我的原始 ModelForm 更改为表单。这解决了我的整个问题。对于 form_valid 问题中的 form_invalid。如果产品不存在，我已经覆盖了表单的 clean_codename 函数以引发 ValidationError。"

我仍然不明白为什么我首先会出现错误。但是，将表单更改为下面的代码就成功了。

表格

class MeasurementForm(forms.Form):
    #the user is allowed to choose any sensor that is related to the measurement table
    sensor = forms.ModelChoiceField(queryset=Sensor.objects.exclude(measurement=None))
    date =  forms.DateField(widget=DateInput(attrs={'format':'%Y-%m-%d'}), initial=datetime.today)