我能指望Django表单中字段验证的顺序吗?

Django文档声称它是按字段定义的顺序排列的。

但我发现它并不总是能兑现诺言。 资料来源: http://docs.djangoproject.com/en/dev/ref/forms/validation/

如上所述,一次一个字段。那个 在表格中声明的顺序 定义),Field.clean()方法 清洁()。最后,一次 这两种方法在每种情况下都会运行 字段、Form.clean()方法或其 执行覆盖。

.keyOrder 不再有效。我认为应该这样做:

from collections import OrderedDict


class MyForm(forms.ModelForm):
    …

    def __init__(self, *args, **kwargs):
        super(MyForm, self).__init__(*args, **kwargs)
        field_order = ['has_custom_name', 'name']
        reordered_fields = OrderedDict()
        for fld in field_order:
            reordered_fields[fld] = self.fields[fld]
        for fld, value in self.fields.items():
            if fld not in reordered_fields:
                reordered_fields[fld] = value
        self.fields = reordered_fields

有些东西可以改变表单顺序,而不管您如何在表单定义中声明它们。其中之一就是如果你用的是 ModelForm ,在这种情况下,除非在 fields 在下面 class Meta 他们将处于一种不可预测的状态。

有一个可靠的解决方案

可以通过设置 self.fields.keyOrder

下面是一些您可以使用的示例代码:

class MyForm(forms.ModelForm):
    has_custom_name = forms.BooleanField(label="Should it have a custom name?")
    name = forms.CharField(required=False, label="Custom name")

    class Meta:
        model = Widget
        fields = ['name', 'description', 'stretchiness', 'egginess']

    def __init__(self, *args, **kwargs):
        super(MyForm, self).__init__(*args, **kwargs)
        ordered_fields = ['has_custom_name', 'name']
        self.fields.keyOrder = ordered_fields + [k for k in self.fields.keys() if k not in ordered_fields]

    def clean_name(self):
        data = self.cleaned_data
        if data.get('has_custom_name') and not data.get('name'):
            raise forms.ValidationError("You must enter a custom name.")
        return data.get('name')

keyOrder 设置, has_custom_name 将被验证(因此出现在 self.cleaned_data )之前 name 已验证。

不能保证这些字段是按特定顺序处理的。官方建议,任何依赖于多个字段的验证都应该在表单的 clean() 方法,而不是特定于字段的 clean_foo() 方法。

表单子类clean()方法。此方法可以执行任何操作 需要从位于的窗体访问多个字段的验证 一次。在这里你可以输入一些东西来检查 字段B必须包含有效的电子邮件地址等。 此方法返回的数据是最终的数据属性 如果重写此方法(默认情况下,Form.clean()只返回 自我清理(数据)。

https://docs.djangoproject.com/en/dev/ref/forms/validation/#using-validators

这意味着,如果你想检查的东西,如电子邮件的价值和家长的电子邮件是不一样的,你应该在该功能内这样做。即:

from django import forms

from myapp.models import User

class UserForm(forms.ModelForm):
    parent_email = forms.EmailField(required = True)

    class Meta:
        model = User
        fields = ('email',)

    def clean_email(self):
        # Do whatever validation you want to apply to this field.
        email = self.cleaned_data['email']
        #... validate and raise a forms.ValidationError Exception if there is any error
        return email

    def clean_parent_email(self):
        # Do the all the validations and operations that you want to apply to the
        # the parent email. i.e: Check that the parent email has not been used 
        # by another user before.
        parent_email = self.cleaned_data['parent_email']
        if User.objects.filter(parent_email).count() > 0:
            raise forms.ValidationError('Another user is already using this parent email')
        return parent_email

    def clean(self):
        # Here I recommend to user self.cleaned_data.get(...) to get the values 
        # instead of self.cleaned_data[...] because if the clean_email, or 
        # clean_parent_email raise and Exception this value is not going to be 
        # inside the self.cleaned_data dictionary.

        email = self.cleaned_data.get('email', '')
        parent_email = self.cleaned_data.get('parent_email', '')
        if email and parent_email and email == parent_email:
            raise forms.ValidationError('Email and parent email can not be the same')
        return self.cleaned_data