根据视图中的条件更改表单中的必填字段（Django）

Question

我有一个表单，LabelingForm() 带有两个多项选择字段，我希望设置所需的 - 参数，以便在按下按钮 A 和 B 时为 False，但在按下按钮 C 时为 True。我尝试使用 initial = False 和required = True 但它不起作用，按下按钮 A 时需要选择字段。

在forms.py中

class LabelingForm(forms.Form):



    First_choices = (('1',''),

             .....
            )

    First_choice = forms.MultipleChoiceField(choices=First_choices, initial=True,required=True)


    Second__choices = (('1',''),

      .....
            )

   Second_choice = forms.MultipleChoiceField(choices=Second_choices, initial=True,required=True)

在views.py中

def function(request, postID):
       if request.method == 'POST':
          form = LabelingForm(request.POST)
          if form.is_valid():

        if "A" in request.POST:
             # required is false 

        if "B" in request.POST:
             # required is false 

        if "C" in request.POST:
             # required is true
           # change required to True 
            form.fields['First_choice'].required = True
            form.fields['Second_choice'].required = True

在模板中

<form  action="" method="post">{% csrf_token %}
 <input type="submit"  name="A" value="Submit A"></input>

 <input type="submit"  name="B" value="Submit B"></input>
 # change so that required is True
 {{ labelingform.first_choice}}{{ labelingform.second_choice}}<input type="submit"  name="C" value="Submit C"></input>

</form>

Answer 1

在调用is_valid()之前更改required属性：

   if request.method == 'POST':
      form = LabelingForm(request.POST)

      required = 'C' in request.POST
      form.fields['First_choice'].required = required
      form.fields['Second_choice'].required = required

      if form.is_valid():
          ...