Django

Question

我正在做一个围绕模型构建的简单调查：

models.py

class Fruits(models.Model):
     author = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
     title = models.CharField(max_length=200, default='')
     text = models.TextField(default='')
     banana = models.BooleanField(default=False)
     grape = models.BooleanField(default=False)
     apple = models.BooleanField(default=False)
     mango = models.BooleanField(default=False)

forms.py

class FruitPicker(ModelForm):
    class Meta:
        model = Fruits
        fields = [
        'title',
        'text',
        'banana',
        'grape',
        'apple',
        'mango'
    ]
    
    widgets = {
        'text': forms.Textarea(attrs={"style": "height:10em;" "width:60em;"}),
        'banana': forms.CheckboxInput(attrs={"style": "margin-left:350px;"}),
        'grape': forms.CheckboxInput(attrs={"style": "margin-left:350px;"}),
        'apple': forms.CheckboxInput(attrs={"style": "margin-left:350px;"}),
        'mango': forms.CheckboxInput(attrs={"style": "margin-left:350px;"})
    }

现在假设我想确保用户必须 select 最少 2 个水果，但最多 3 个。我将如何在后端执行此操作？

Answer 1

您可以覆盖表单的 clean 方法来检查是否检查了两到三个 BooleanField：

from django.core.exceptions import <strong>ValidationError</strong>

class FruitPicker(ModelForm):
     # ⋮

    def <strong>clean</strong>(self, *args, **kwargs):
        data = super().clean(*args, **kwargs)
        total = sum([data[x] for x in ['banana', 'grape', 'apple', 'mango']])
        if not (2 <= total <= 3):
            raise ValidationError('You should select between 2 and 3 fruits.')
        return data

这里sum(…)对boolean求和，False用0，True用1，这样算出True秒。如果该数字不在 2 和 3 之间，则会引发 ValidationError.

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django-models

django-forms

django-model-field