Django 自定义表单验证最佳实践？

Question

我有一个包含 5 对位置和描述的表单。我有三组验证需要完成

• 您至少需要输入一个位置
• 对于第一个位置，您必须有描述
• 对于每对剩余的位置和描述

阅读 Django 文档后，我想出了以下代码来进行这些自定义验证

def clean(self):
    cleaned_data = self.cleaned_data
    location1 = cleaned_data.get('location1')
    location2 = cleaned_data.get('location2')
    location3 = cleaned_data.get('location3')
    location4 = cleaned_data.get('location4')
    location5 = cleaned_data.get('location5')
    description1 = cleaned_data.get('description1')
    description2 = cleaned_data.get('description2')
    description3 = cleaned_data.get('description3')
    description4 = cleaned_data.get('description4')
    description5 = cleaned_data.get('description5')
    invalid_pairs_msg = u"You must specify a location and description"

    # We need to make sure that we have pairs of locations and descriptions
    if not location1:
        self._errors['location1'] = ErrorList([u"At least one location is required"])

    if location1 and not description1:
        self._errors['description1'] = ErrorList([u"Description for this location required"])

    if (description2 and not location2) or (location2 and not description2):
        self._errors['description2'] = ErrorList([invalid_pairs_msg])

    if (description3 and not location3) or (location3 and not description3):
        self._errors['description3'] = ErrorList([invalid_pairs_msg])

    if (description4 and not location4) or (location4 and not description4):
        self._errors['description4'] = ErrorList([invalid_pairs_msg])

    if (description5 and not location5) or (location5 and not description5):
        self._errors['description5'] = ErrorList([invalid_pairs_msg])

    return cleaned_data     

现在，它可以工作了但是它看起来真的很难看。我正在寻找一种更“Pythonic”和“Djangoist”（？）的方式来做到这一点。提前致谢。

Answer 1

您可以做的第一件事是简化测试，以查看是否只填充了两个字段中的一个。你可以这样实现逻辑xor：

if bool(description2) != bool(location2): 

或者这样：

if bool(description2) ^ bool(location2):

我还认为，如果您分别为每个字段实现一个干净的方法，这会更清楚，如the docs 中所述。这可以确保错误将显示在正确的字段中，并且让您只需引发 forms.ValidationError 而不是直接访问 _errors 对象。

例如：

def _require_together(self, field1, field2):
    a = self.cleaned_data.get(field1)
    b = self.cleaned_data.get(field2)
    if bool(a) ^ bool(b):
        raise forms.ValidationError(u'You must specify a location and description')
    return a

# use clean_description1 rather than clean_location1 since
# we want the error to be on description1
def clean_description1(self):
    return _require_together('description1', 'location1')

def clean_description2(self):
    return _require_together('description2', 'location2')

def clean_description3(self):
    return _require_together('description3', 'location3')

def clean_description4(self):
    return _require_together('description4', 'location4')

def clean_description5(self):
    return _require_together('description5', 'location5')

为了获得需要location1 的行为，只需将required=True 用于该字段，它将被自动处理。

Answer 2

至少可以减少一些代码。有 'location1' 和 'description1' Required=True （正如 TM 和 stefanw 指出的那样）。那么，

def clean(self):
   n=5
   data = self.cleaned_data
   l_d = [(data.get('location'+i),data.get('description'+i)) for i in xrange(1,n+1)]
   invalid_pairs_msg = u"You must specify a location and description"

   for i in xrange(1,n+1):
      if (l_d[i][1] and not l_d[i][0]) or (l_d[i][0] and not l_d[i][1]):
         self._errors['description'+i] = ErrorList([invalid_pairs_msg])
   return data

虽然还是很丑...