不属于表单的字段的Perfom Django验证

问题描述

我想基于Django模型中的字段之一引发ValidationError，而不必将各个字段作为ModelForm的一部分提交。经过一番搜寻后，我发现模型验证器的概念。因此，我尝试执行以下操作：

def minimumDuration(value):
    if value == 0:
        raise ValidationError("Minimum value accepted is 1 second!")

class PlaylistItem(models.Model):
    position = models.IntegerField(null=False)
    content = models.ForeignKey(Content,null=True,on_delete=models.SET_NULL)
    item_duration = models.IntegerField(validators = [minimumDuration],default = 5,blank=True)
    playlist = models.ForeignKey(Playlist,on_delete=models.CASCADE)

但是，当我在各个字段中引入0时，没有错误出现。从Django的文档中，我发现保存模型时不会自动应用验证器。它将我重定向到this page，但我并不真正了解如何应用这些内容。有想法吗？

解决方法

以下是在模型外部具有这样的自定义字段的表单示例：

class ExampleForm(forms.ModelForm):
    custom_field = forms.BooleanField(
        label='Just non model field,replace with the type you need',required=False
    )

    class Meta:
        model = YourModel

    def __init__(self,*args,**kwargs):
        super().__init__(*args,**kwargs)
        # optional: further customize field widget
        self.fields['restrict_countries'].widget.attrs.update({
            'id': self.instance.pk + '-custom_field','class': 'custom-field-class'
        })
        # optional: further customize field widget
        self.fields['restrict_countries'].initial = self._get_custom_initial()

    def _get_custom_initial(self):
        # compute initial value based on self.instance and other logic
        return True

    def _valid_custom_field(value):
        # validate your value here
        # return Boolean

    def clean(self):
        """
        The important method: override clean to hook your validation
        """
        super().clean()
        custom_field_val = self.cleaned_data.get('custom_field')
        if not self._valid_custom_field(custom_field_val):
            raise ValidationError(
                'Custom Field is not valid')