如何使 RadioSelect 非强制并删除 ModelForm 中的默认选项？

Question

编辑我的问题与可能的重复问题不同的原因是因为这并没有解决使其非 manditory 同时还删除了默认选项“-------”

我想在forms.ModelForm 中提出一个RadioSelect 调查问题非强制性

要使用RadioSelect，我将在我的ModelForm（下）中添加小部件，因为Djangos 模型不提供RadioSelect 或Select 小部件。

执行此操作的标准方法是将Blank=True 作为参数传递。然而，正如我在另一个问题中发现的那样，我问了it turns out that if you pass blank=True as an argument from models.CharField to the forms.RadioSelect widget it will leave the default option "-------" in place even if you use default=None.

我必须删除默认选项“-------”。

那么，如何在不包括默认选项“-------”的同时使 RadioSelect 问题成为非强制性问题？

谢谢

forms.py

class SurveyFormB(forms.ModelForm): 

    class Meta:
        model = Person
        fields = ['internet_usage', 'smart_phone_ownership', 'smart_phone_usage']        

        widgets = {'internet_usage' : forms.RadioSelect,
                   'smart_phone_ownership' : forms.Select,
                   'smart_phone_usage' : forms.RadioSelect,
                   }

models.py

#How often do you use the Internet?  
INTERNET_LESS_THAN_ONE_HOUR_A_DAY = 'Less than one hour per day'
INTERNET_ONE_TO_TWO_HOURS_A_DAY = '1 - 2 hours per day'
INTERNET_TWO_TO_FOUR_HOURS_A_DAY = '2 - 4 hours per day'
INTERNET_FOUR_TO_SIX_HOURS_A_DAY = '4 - 6 hours per day'
INTERNET_SIX_TO_EIGHT_HOURS_A_DAY = '6 - 8 hours per day'
INTERNET_EIGHT_PLUS_HOURS_A_DAY = '8 + hours per day'

INTERNET_USAGE = (
    (INTERNET_LESS_THAN_ONE_HOUR_A_DAY, 'Less than one hour a day'),
    (INTERNET_ONE_TO_TWO_HOURS_A_DAY, '1 - 2 hours a day'),
    (INTERNET_TWO_TO_FOUR_HOURS_A_DAY, '2 - 4 hours a day'),
    (INTERNET_FOUR_TO_SIX_HOURS_A_DAY, '4 - 6 hours a Day'),
    (INTERNET_SIX_TO_EIGHT_HOURS_A_DAY, '6 - 8 hours a day'),
    (INTERNET_EIGHT_PLUS_HOURS_A_DAY, '8 + hours a day'),
           )

internet_usage = models.CharField(null=True, max_length=100, default=None, choices=INTERNET_USAGE, verbose_name='How long do you spend on the Internet each day?')

Answer 1

考虑NickJ 的答案并使用RadioSelectNotNull 如下：

forms.py

from itertools import chain
from django.forms import RadioSelect
from django.utils.encoding import force_unicode

class RadioSelectNotNull(RadioSelect):

    def get_renderer(self, name, value, attrs=None, choices=()):
        """Returns an instance of the renderer."""
        if value is None: value = ''
        str_value = force_unicode(value) # Normalize to string.
        final_attrs = self.build_attrs(attrs)
        choices = list(chain(self.choices, choices))
        if choices[0][0] == '':
            choices.pop(0)
        return self.renderer(name, str_value, final_attrs, choices)


class SurveyFormB(forms.ModelForm): 

    class Meta:
        model = Person
        fields = ['internet_usage', 'smart_phone_ownership', 'smart_phone_usage']        

        widgets = {'internet_usage' : RadioSelectNotNull,
                   'smart_phone_ownership' : forms.Select,
                   'smart_phone_usage' : RadioSelectNotNull,
                   }

请注意，如果您还可以将选项字段修改为：

models.py

INTERNET_USAGE = (
    ("One", 'Less than one hour a day'),
    ( "Two", '1 - 2 hours a day'),
    ( "Three", '2 - 4 hours a day'),
    ( "Four", '4 - 6 hours a Day'),
    ( "Five", '6 - 8 hours a day'),
    ( "Six", '8 + hours a day'),
)

internet_usage = models.CharField(null=True, max_length=100, default=None, choices=INTERNET_USAGE, verbose_name='How long do you spend on the Internet each day?')