我的模型是这样的:
class Post(models.Model):
user = models.ForeignKey(User)
post = models.CharField(max_length=400)
subject = models.ForeignKey(Subject, blank=True, null=True)
这是我的序列化器:
class PostSerializer(serializers.ModelSerializer):
class Meta:
model = Post
fields = ('user', 'post', 'subject')
def create(self, validated_data):
post = Post(
user = User.objects.get(username='A'),
post = validated_data['post'],
)
此时,我想检查最终用户是否提供了“主题”,如果是,则添加该字段然后保存帖子对象(否则,保存帖子对象而不添加“主题”字段)。我打开了 python shell 并这样做了:
p = PostSerializer(data={'user':16, 'post':'p'})
p.is_valid()
# returned True
if p.validated_data['subject']:
print('exists')
else:
print('does not exist')
这会返回一个错误说:
Traceback (most recent call last):
File "<console>", line 1, in <module>
KeyError: 'subject'
话虽如此,检查验证字段是否存在的正确方法是什么?