如何通过点使用pydantic json字段

Question

我有这样的模型、枚举、字段：

from pydantic import BaseModel, Json

class SlotActionEnum(Enum):
    NORMAL = 'normal'
    REASK = 'reask'


class ChannelMessage(Json):
    answerText: str
    slot_action: SlotActionEnum = SlotActionEnum.NORMAL 


class Request(BaseModel):
    conversationId: str
    channelMessage: ChannelMessage



o = Request(**{
    "conversationId": "id10",
    "channelMessage": "{\"answerText\": \"sadfg\", \"slot_action\": \"reask\"}"
})

这里有两个问题：

1. slot_action不能像这样访问：o.channelMessage.slot_action

这会导致AttributeError：

AttributeError: 'dict' object has no attribute 'slot_action'

如果我通过方括号访问此字段：

1. slot_action中的值不是slotaconenum，而是类似于reask或normal的值

2. slot_action可以是空字符串。如何将空字符串替换为normal

我应该如何处理这些问题？我是否应该这样做：

class ChannelMessage(BaseModel):
    answerText: str
    slot_action: SlotActionEnum = SlotActionEnum.NORMAL

class Request(BaseModel):
    conversationId: str
    channelMessage: ChannelMessage

    def __init__(__pydantic_self__, **data: Any) -> None:
        channel_message = json.loads(data.pop('channelMessage'))
        if channel_message['slot_action'] == '':
            channel_message['slot_action'] = SlotActionEnum.NORMAL.value
        channel_message['slot_action'] = SlotActionEnum(channel_message['slot_action'])
        super().__init__(**data, channelMessage=channel_message)

?？好吧，这很管用，但看起来很难看

Answer 1

from pydantic import BaseModel, validator
from enum import Enum


class SlotActionEnum(Enum):
    NORMAL = 'normal'
    REASK = 'reask'


class ChannelMessage(BaseModel):
    answerText: str
    slot_action: SlotActionEnum = SlotActionEnum.NORMAL

    @validator("slot_action", pre=True)
    def valid_slot_action(cls, v):
        if v == "":
            return SlotActionEnum.NORMAL
        return v


class Request(BaseModel):
    conversationId: str
    channelMessage: ChannelMessage

    @validator("channelMessage", pre=True)
    def valid_channel_message(cls, v):
        if isinstance(v, str):
            return ChannelMessage.parse_raw(v)
        return v


o = Request(**{
    "conversationId": "id10",
    "channelMessage": "{\"answerText\": \"sadfg\", \"slot_action\": \"reask\"}"
})