为什么是我的形式。当我尝试在表单中访问时,清理的数据不同。clean_field方法?

我的表单中的数据清理有问题。在我的单个字段清理方法中调用调试器时,清理后的版本中有一半数据丢失。下面是代码的简化版本:

class MealForm(forms.Form):
    def __init__(self, *args, **kwargs):
        # call super(), do some stuff, then declare some fields:
        self.fields['meal'] = forms.CharField(required=True, max_length=255)
        self.fields['sugar'] = forms.CharField(required=False, max_length=255)
        self.fields['salt'] = forms.CharField(required=False, max_length=255)

    def clean_meal(self):
        pdb.set_trace() # insert a breakpoint to inspect self.cleaned_data.keys() and self.data.keys()
        meal_value = self.cleaned_data['meal']
        # dict of all the various utility functions because python doesn't have 'switch'
        process_meal_type = {
            'dessert': self.process_sugar,
            'main course': self.process_salt,
        }
        try:
            process_meal_type[meal_value]()
        except KeyError:
            raise forms.ValidationError( "Incorrect meal type: " + str(meal_value) )
        return meal_value

   def process_sugar(self):
       if not self.cleaned_data.get('sugar'):
           raise ValidationError ( "Desserts must contain sugar")
       else:
           do_something_with_the_sugar_data()

如果我发表评论 clean_meal 并在 clean ,我注意到 self.cleaned_data 如预期的那样:所有表单字段都存在并已入账。我不是给个人打电话 clean_* 方法。

发生什么事?