如何让 Django FormSet 接受 m2m 但将它们存储为多个 FK 记录?

Question

我需要为学生提供一个测试，但有些问题接受多个答案。

我可以让它创建多个记录来存储多个答案而不是使用 M2M 吗？

例如，如果学生为问题选择 A 和 B，则操作如下：

StudentAnwer.objects.create(question=question, answer=answer_a)
StudentAnwer.objects.create(question=question, answer=answer_b)

formsets.py

from django import forms
StudentAnswerFormSet = forms.inlineformset_factory(
Student,
StudentAnswer,
fields=['question', 'answer', ],
formset=forms.BaseInlineFormSet)

models.py

class Question(BaseModel):
title = models.CharField(max_length=250)
is_multiple = models.BooleanField(default=False)
class StudentAnswer(BaseModel):
student = models.ForeignKey(Student, related_name='answers')
question = models.ForeignKey(Question, related_name='student_answers')
answer = models.ForeignKey(Answer, related_name='student_answers')

views.py

from formtools.wizard.views import SessionWizardView
class StudentWizardView(SessionWizardView):
...
def get_answer_form(self, step=None, data=None, files=None):
...
question_list = get_question_list()
return forms.inlineformset_factory(
Student,
StudentAnswer,
fields=['question', 'answer', ],
extra=len(question_list),
formset= forms.BaseInlineFormSet)
def get_form(self, step=None, data=None, files=None):
form = super(StudentWizardView, self).get_form(step, data, files)
# determine the step if not given
if step is None:
step = self.steps.current
if step == self.STEP_ANSWER:
initial_dict = self.get_form_initial(step)
prev_form_data = self.get_cleaned_data_for_step(self.STEP_PROFILE)
form = self.get_answer_form(step, data, files)
for form_index in range(len(initial_dict.keys())):
question = initial_dict[form_index]['question']
answer_list = question.get_answer_list()
if question.is_multiple:
form.forms[form_index].fields['answer'] = ModelMultipleChoiceField(queryset=answer_list,
             widget=CheckboxSelectMultiple)
else:
form.forms[form_index].fields['answer'].widget.choices.queryset = answer_list

我试图避免使用 M2M，以便更轻松地在模板上显示每个问题的可能答案。

{{ wizard.management_form }}
{{ wizard.form.management_form }}
{% for answer_form in wizard.form.forms %}
{{ answer_form.question }}
{{ answer_form.answer }}
{% for hidden in answer_form.hidden_fields %}
{{ hidden }}
{% endfor %}
{% endfor %}

Answer 1

通过使用原始form.data而不是form.cleaned_data解决了这个问题，因此可以在清理之前访问同一字段的多个值。

这是有风险的，但您可以仅针对您希望它起作用的部分复制清理方法。

还通过以下方式制作了自定义复选框列表：

{% for choice in field.field.choices %}
<input type="checkbox" id="id_{{ field.html_name }}_{{ forloop.counter }}" name="{{ field.html_name }}" value="{{ choice.id }}"{% if choice.id in field.value %} checked="checked"{% endif %}> {{ choice }}
{% endfor %}

并删除了自定义表单字段，因此它们都是：

form.forms[form_index].fields['answer'].widget.choices.queryset = answer_list