serializers.py 文件源码

def __getitem__(self, key):
        field = self.fields[key]
        value = self.data.get(key)
        error = self.errors.get(key) if hasattr(self, '_errors') else None
        if isinstance(field, serializers.Serializer):
            return serializers.NestedBoundField(field, value, error)
        return serializers.BoundField(field, value, error)