如何在Django表单中传递self.request数据？

我希望在表单类中传递self.request数据，目前可在View中访问它，但无法在表单类中访问。

我的视图代码：

class AttendanceCreateView(LoginRequiredMixin, CreateView):
    model = Attendance
    template_name = 'attendance/attendances_new.html'
    form_class = AttendanceForm

    def get_initial(self):
        initial = super().get_initial()
        initial['class_name'] = self.request.GET.get('class', '')
        return initial

我的表单类代码：

class AttendanceForm(forms.ModelForm):
    class_name = forms.ChoiceField(choices=CLASS_NAMES, disabled=True)
    teacher = forms.ModelMultipleChoiceField(
        queryset=Teacher.objects.all().order_by('id'))
    subject_name = forms.ChoiceField(choices=[])
    total_students = forms.IntegerField(initial=0)
    unique_code = forms.IntegerField(initial=0)

    class Meta:
        model = Attendance
        fields = ['class_name', 'teacher', 'subject_name',
                  'total_students', 'unique_code']

    def __init__(self, *args, **kwargs):
        super(AttendanceForm, self).__init__(*args, **kwargs)
        
        # 我需要实现的逻辑
        # if self.request.GET.get('class', '') = 'class1':
        #    self.fields['subject_name'].choices = MY_CHOICES_1 
        # elif self.request.GET.get('class', '') = 'class2':
        #    self.fields['subject_name'].choices = MY_CHOICES_2

我希望根据传入的request值设置subject_name的选项，如class1对应MY_CHOICES_1，class2对应MY_CHOICES_2，获取request数据十分关键。请问能否像设置class_name那样直接在View中设置初始选项？或有什么在表单中实现的建议？

方案一：在View中直接设置字段选项 #

如果逻辑简单、无需在表单中复用，可以直接在View的get_form方法中修改表单字段的选项：

class AttendanceCreateView(LoginRequiredMixin, CreateView):
    model = Attendance
    template_name = 'attendance/attendances_new.html'
    form_class = AttendanceForm

    def get_initial(self):
        initial = super().get_initial()
        initial['class_name'] = self.request.GET.get('class', '')
        return initial
    
    def get_form(self, form_class=None):
        form = super().get_form(form_class)
        # 获取request中的class参数
        class_param = self.request.GET.get('class', '')
        # 根据参数设置subject_name的选项
        if class_param == 'class1':
            form.fields['subject_name'].choices = MY_CHOICES_1
        elif class_param == 'class2':
            form.fields['subject_name'].choices = MY_CHOICES_2
        return form

方案二：将request传递给表单类处理 #

如果需要在表单中复用该逻辑，或者逻辑较为复杂，可以通过get_form_kwargs方法将request传入表单：

第一步：修改View类

class AttendanceCreateView(LoginRequiredMixin, CreateView):
    model = Attendance
    template_name = 'attendance/attendances_new.html'
    form_class = AttendanceForm

    def get_initial(self):
        initial = super().get_initial()
        initial['class_name'] = self.request.GET.get('class', '')
        return initial
    
    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        # 将request添加到表单的参数中
        kwargs['request'] = self.request
        return kwargs

第二步：修改表单类

class AttendanceForm(forms.ModelForm):
    class_name = forms.ChoiceField(choices=CLASS_NAMES, disabled=True)
    teacher = forms.ModelMultipleChoiceField(
        queryset=Teacher.objects.all().order_by('id'))
    subject_name = forms.ChoiceField(choices=[])
    total_students = forms.IntegerField(initial=0)
    unique_code = forms.IntegerField(initial=0)

    class Meta:
        model = Attendance
        fields = ['class_name', 'teacher', 'subject_name',
                  'total_students', 'unique_code']

    def __init__(self, *args, **kwargs):
        # 从kwargs中取出request，需在调用super()之前弹出，避免父类构造器报错
        self.request = kwargs.pop('request', None)
        super(AttendanceForm, self).__init__(*args, **kwargs)
        
        if self.request:
            class_param = self.request.GET.get('class', '')
            if class_param == 'class1':
                self.fields['subject_name'].choices = MY_CHOICES_1 
            elif class_param == 'class2':
                self.fields['subject_name'].choices = MY_CHOICES_2

内容的提问来源于stack exchange，提问作者Vilashkumar Daate