python - 使用 Django Rest Frame 序列化非 django 模型

Question

我正在尝试使用 DRF 构建一个 django 模型，该模型在创建后发送对象状态有效负载，或者发送错误有效负载。当我尝试做类似的事情时，我收到以下错误消息:


File "/Users/user/projects/bowling-game/env/lib/python3.6/site-packages/rest_framework/serializers.py", line 527, in to_representation
ret[field.field_name] = field.to_representation(attribute)
File "/Users/user/projects/bowling-game/env/lib/python3.6/site-packages/rest_framework/serializers.py", line 683, in to_representation
self.child.to_representation(item) for item in iterable
File "/Users/user/projects/bowling-game/env/lib/python3.6/site-packages/rest_framework/serializers.py", line 683, in <listcomp>
self.child.to_representation(item) for item in iterable
File "/Users/user/projects/bowling-game/env/lib/python3.6/site-packages/rest_framework/serializers.py", line 510, in to_representation
fields = self._readable_fields
File "/Users/user/projects/bowling-game/env/lib/python3.6/site-packages/django/utils/functional.py", line 36, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/Users/user/projects/bowling-game/env/lib/python3.6/site-packages/rest_framework/serializers.py", line 376, in _readable_fields
field for field in self.fields.values()
File "/Users/user/projects/bowling-game/env/lib/python3.6/site-packages/rest_framework/serializers.py", line 363, in fields
for key, value in self.get_fields().items():
File "/Users/user/projects/bowling-game/env/lib/python3.6/site-packages/rest_framework/serializers.py", line 997, in get_fields
serializer_class=self.__class__.__name__
AssertionError: Class ErrorSerializer missing "Meta" attribute


我的模型如下:

class BaseModel(models.Model, object):
    # Encapsulates all error objects.
    errors= []

    def add_error(self, error_object):
        """Appends the error to the list of errors."""
        self.errors.append(error_object)

    class Meta:
        abstract = True
        app_label = 'game'


class GameRegistration(BaseModel):
    """Instance of this class represents the user playing the bowling game."""

    game_id = models.CharField(max_length=32,
        help_text='Unique bowling game id', primary_key=True,
        default=functools.partial(random_string, char_length=16))
    #  I will set the request.user to set the details later on, but not now.
    user_name = models.CharField(help_text='unique username', default='test', max_length=32)
    created_timestamp = models.DateTimeField(default=datetime.datetime.now)

    class Meta:
        indexes = [
            models.Index(fields=['game_id'])
        ]


class Error(object):
    """
    An instance of this class encapsulates the error code and the message to be
    returned.
    """
    def __init__(self, error_code, error_message):
        self.error_code = error_code
        self.error_message = error_message

    def __repr__(self):
        return '{}:{}'.format(self.__class__.__name__, self.__dict__)

我的序列化器实现

class BaseSerializer(serializers.ModelSerializer, object):
    pass

class ErrorSerializer(BaseSerializer):
    """Representation of any error resulting in any of the operation."""
    error_code = serializers.IntegerField()
    error_message = serializers.CharField(max_length=200)

    class Meta:
        ordering=('error_code',)

class GameRegistrationSerializer(BaseSerializer):
    """Serializer representation of game instance."""
    game_id = serializers.PrimaryKeyRelatedField(read_only=True)


    def to_representation(self, instance):
        return {
            'game_id': str(instance.game_id),
            'created': instance.created_timestamp
        }

    class Meta:
        model = models.GameRegistration
        fields = ('game_id', 'created')
        read_only_fields = ('game_id', 'created')

我想要一种序列化 errors 的方法有效负载中的 json 数组。它不绑定(bind)到任何 django 模型。它封装了与其他 django 模型相关的所有错误。这个想法是，如果我能够创建 GameRegistration ，然后我将返回以下有效负载


{
'game_id': 'ABCDabcd1234',
'created': '<created stamp>'
}


如果出现错误，我将返回有效负载，如下所示:
{
'errors': {
'error_code': 500,
'error_message': 'Server error'
}
}


Answer 1

从 Serializer 类继承 BaseSerializer，而不是从 ModelSerializer 继承。因此 BaseSerializer 将类似于

class BaseSerializer(serializers.<b>Serializer</b>, object):
    pass

ModelSerializer 的问题是，它期望一个 Meta 类，其中至少有两个字段，其中 fields 和型号