从列表中选择值时如何调出值

问：

我们需要聪明人的帮助。 我有以下型号

class PCModel(models.Model):
      PC_name = models.CharField('Названние компьютера', max_length=60)
      CPU = models.ForeignKey('CPUModel', verbose_name='Процессор', on_delete=models.SET_NULL, blank=True, null=True)
      GPU = models.ForeignKey('GPUModel', verbose_name='Видеокарта', on_delete=models.CASCADE, blank=True, null=True)
      RAM = models.ForeignKey('RAMModel', verbose_name='Оперативная память', on_delete=models.CASCADE, blank=True,
                        null=True)
      Motherboard = models.ForeignKey(
    'MotherboardModel', verbose_name='Материнская  плата', on_delete=models.CASCADE, blank=True, null=True
)
      HDD = models.ForeignKey('HDDModel', verbose_name='HDD', on_delete=models.CASCADE, blank=True, null=True)
      SSD = models.ForeignKey('SSDModel', verbose_name='SSD', on_delete=models.CASCADE, blank=True, null=True)
      Power_suppy = models.ForeignKey('Power_suppyModel', verbose_name='Блок питания', on_delete=models.CASCADE,
                                blank=True, null=True)
      Case = models.ForeignKey('CaseModel', verbose_name='Корпус', on_delete=models.CASCADE, blank=True, null=True)
      purchase_price = models.IntegerField('Стоимость покупки', default=0)
      cost_of_sale = models.IntegerField('Стоимость продажи', default=0)
      profit = models.IntegerField('Прибыль', default=0)
      slug = models.SlugField(unique=True, blank=True, null=True)
      sold = models.BooleanField('Статус', default=False)

      def __str__(self):
          return self.PC_name

      def get_absolute_url(self):
          return reverse("pcmodel_detail", kwargs={"slug": self.slug})

      def save(self, *args, **kwargs):
          self.slug = self.slug
          super(PCModel, self).save(*args, **kwargs)

和

class CPUModel(models.Model):
      manufacturer = models.CharField(max_length=15, choices=manufacturer_choice)
      name = models.CharField(max_length=50)
      number_of_cores = models.IntegerField('Количество ядер', choices=number_choice)
      number_of_threads = models.IntegerField('Количество потоков', choices=number_choice)
      base_frequency = models.IntegerField('Базовая частота', choices=frequency_choice)
      turbo_boost = models.IntegerField('Частота Turbo boost', choices=frequency_choice)
      socket = models.IntegerField('Сокет', choices=socket_choice)
      TDP = models.IntegerField('Тепловыделение (TDP)', choices=TDP_choice)
      RAM_type = models.CharField('Поддерживаемый тип памяти', choices=RAM_type_choice, max_length=5)
      purchase_price = models.IntegerField('Цена закупки')
      count = models.IntegerField('Количество')
      in_stock = models.BooleanField('Наличие', default=False)

      def __str__(self):
          return self.name

      def __int__(self):
          return self.purchase_price

      def get_purchase(self):
          return self.purchase_price

有一个表格

class AddPCForm(forms.ModelForm):
      CPUModel = ModelChoiceField(label='', queryset=CPUModel.objects.all(), empty_label='')

      class Meta:
          model = PCModel
          fields = [
              'PC_name', 'CPU', 'GPU', 'RAM', 'Motherboard', 'HDD', 'SSD', 'Power_suppy', 'Case', 'purchase_price', 'sold'
          ]

它看起来像这样

有必要确保在选择处理器时，价格会自动与价格字段绑定。这怎么能做到呢？ 我在考虑CPUModel.objects.raw（SQL查询），它会起作用吗？也许其他人知道如何实现它。 在选择处理器（процессор）时，它的价格必须在价格（цена）字段中自动拉高。