Django数据库缓存

我有一个Django表单,它使用一个整型字段按主键查找模型对象。表单有一个 save() 方法,该方法使用整数字段引用的模型对象。模特的经理 get() 方法被调用两次,一次在clean方法中,一次在 保存() 方法:

class MyForm(forms.Form):
    id_a = fields.IntegerField()

    def clean_id_a(user_id):
        id_a = self.cleaned_data['id_a']
        try:
            # here is the first call to get
            MyModel.objects.get(id=id_a)
        except User.DoesNotExist:
            raise ValidationError('Object does not exist')

    def save(self):
        id_a = self.cleaned_data['id_a']
        # here is the second call to get
        my_model_object = MyModel.objects.get(id=id_a)

        # do other stuff

我不确定这是两次还是一次命中数据库,所以我用clean方法返回对象本身,这样就可以避免第二次 获取() 获取()

class MyForm(forms.Form):
    id_a = fields.IntegerField()

    def clean_id_a(user_id):
        id_a = self.cleaned_data['id_a']
        try:
            # here is my workaround
            return MyModel.objects.get(id=id_a)
        except User.DoesNotExist:
            raise ValidationError('Object does not exist')

    def save(self):
        # looking up the cleaned value returns the model object
        my_model_object = self.cleaned_data['id_a']

        # do other stuff