小编zym*_*mud的帖子

问题:如何在表单和序列化器中编写用于字段验证的DRY代码？

示例:我有简单的django应用程序与模型形式,它验证passengers字段为Order:

def clean_passengers(self):
    passengers = self.cleaned_data['passengers']
    if passengers > self.flight.available_seats:
        raise forms.ValidationError(
            _(u'''Passengers count can`t be greater then seats count'''))
    return passengers

和Order串行器中的验证相同的代码:

def validate_passengers(self, attrs, source):
    passengers = attrs[source]
    if passengers > self.flight.available_seats:
        raise serializers.ValidationError(
            _(u'''Passengers count can`t be greater then seats count'''))
    return attrs

这不是干的,我写了两次相同的逻辑.我怎么能避免这个？也许我可以从表单或类似的东西继承序列化程序.

我有mixin和型号:

class Mixin(object):
    field = GenericRelation('ModelWithGR')

class MyModel(Mixin, models.Model):
   ...

但是django不会把GenericRelation场变成GenericRelatedObjectManager:

>>> m = MyModel()
>>> m.field
<django.contrib.contenttypes.fields.GenericRelation>

当我将字段放入模型本身或抽象模型时 - 它工作正常:

class MyModel(Mixin, models.Model):
   field = GenericRelation('ModelWithGR')

>>> m = MyModel()
>>> m.field
<django.contrib.contenttypes.fields.GenericRelatedObjectManager at 0x3bf47d0>

我怎样才能GenericRelation在mixin中使用？