python Django 表单验证：使“必需”成为条件？
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Django form validation: making "required" conditional?
提问by ChrisW
I'm new to Django (and Python), and am trying to figure out how to conditionalize certain aspects of form validation. In this case, there's a HTML interface to the application where the user can choose a date and a time from widgets. The cleanmethod on the form object takes the values of the time and date fields and turns them back into a datetime.
我是 Django（和 Python）的新手，我正在尝试弄清楚如何对表单验证的某些方面进行条件化。在这种情况下，应用程序有一个 HTML 界面，用户可以在其中从小部件中选择日期和时间。的clean形式对象方法需要的时间和日期字段的值，并把它们放回一个datetime。
In addition to the HTML interface, there's also an iPhone client making calls into the application, and I'd like to pass a UNIX timestamp-style time value in.
除了 HTML 界面，还有一个 iPhone 客户端调用应用程序，我想传入一个 UNIX 时间戳样式的时间值。
My form code looks like this:
我的表单代码如下所示：
class FooForm(forms.ModelForm):
foo_date = forms.CharField(required=True, widget=forms.RadioSelect(choices=DATE_CHOICES))
foo_time = forms.CharField(required=True, widget=SelectTimeWidget())
foo_timestamp = forms.CharField(required=False)
How do I make foo_dateand foo_timerequired unlessfoo_timestampis provided?
除非提供foo_date，否则我如何制作和foo_time要求？foo_timestamp
回答by Benjamin Wohlwend
This is done with the cleanmethod on the form. You need to set foo_dateand foo_timeto required=False, though, because cleanis only called after every field has been validated (see also the documentation).
这是通过clean表单上的方法完成的。你需要设置foo_date并foo_time到required=False，不过，因为clean每个领域已被证实后，才会调用（另见文档）。
class FooForm(forms.Form)
# your field definitions
def clean(self):
data = self.cleaned_data
if data.get('foo_timestamp', None) or (data.get('foo_date', None) and data.get('foo_time', None)):
return data
else:
raise forms.ValidationError('Provide either a date and time or a timestamp')
回答by Elliott
I found myself needing a "standard" way to do this, as my forms have several conditionally required fields. So I created a superclass with the following method:
我发现自己需要一种“标准”的方式来做到这一点，因为我的表单有几个有条件的必填字段。所以我用以下方法创建了一个超类：
def validate_required_field(self, cleaned_data, field_name, message="This field is required"):
if(field_name in cleaned_data and cleaned_data[field_name] is None):
self._errors[field_name] = self.error_class([message])
del cleaned_data[field_name]
And then in my form's clean method I have:
然后在我的表单的干净方法中，我有：
def clean(self):
cleaned_data = super(FormClass, self).clean()
if(condition):
self.validate_required_field(cleaned_data, 'field_name')
It's worked perfectly for me so far.
到目前为止，它对我来说非常有效。
