Pydantic 对我的类型和他们的联合感到困惑

Question

我有以下 Pydantic 模型类型方案规范：

class RequestPayloadPositionsParams(BaseModel):
    """
    Request payload positions parameters
    """

    account: str = Field(default="COMBINED ACCOUNT")
    fields: List[str] = Field(default=["QUANTITY", "OPEN_PRICE", "OPEN_COST"])


class RequestPayloadPositions(BaseModel):
    """
    Request payload positions service
    """

    header: RequestPayloadHeader = Field(
        default=RequestPayloadHeader(service="positions", id="positions", ver=0)
    )
    params: RequestPayloadPositionsParams = Field(
        default=RequestPayloadPositionsParams()
    )


class RequestPayloadOrdersParams(BaseModel):
    """
    Request payload orders parameters
    """

    account: str = Field(default="COMBINED ACCOUNT")
    types: List[str] = Field(default=["WORKING", "FILLED", "CANCELED"])


class RequestPayloadOrders(BaseModel):
    """
    Request payload orders service
    """

    header: RequestPayloadHeader = Field(
        default=RequestPayloadHeader(service="order_events", id="order_events", ver=0)
    )
    params: RequestPayloadOrdersParams = Field(default=RequestPayloadOrdersParams())


class RequestPayload(BaseModel):
    """
    Request payload data
    """

    payload: List[Union[RequestPayloadPositions, RequestPayloadOrders]] = Field(...)

现在，我想为订单和头寸服务创建一个负载对象：

positions = requests.RequestPayload(payload=[requests.RequestPayloadPositions()])
orders = requests.RequestPayload(payload=[requests.RequestPayloadOrders()])

现在，positions 的类型为 requests.RequestPayload[payload= requests.RequestPayloadPositions ... 但 orders 没有 requests.RequestPayload[payload= requests.RequestPayloadOrders，但与 positions 相同。这是错误的。

我可以通过将模型规范从 payload: List[Union[RequestPayloadPositions, RequestPayloadOrders]] = Field(...) 更改为 payload: List[Any] = Field(...) 来解决此问题...但我想明确定义允许的类型。

知道如何解决这个问题，或者我应该解释得更详细吗？你明白我的问题了吗？

编辑工作代码示例，显示最后一行中的第二个断言失败，但不应失败...

from typing import List, Union
from pydantic import BaseModel, Field


class RequestPayloadHeader(BaseModel):
    """
    Request payload header
    """

    service: str = Field(...)
    id: str = Field(...)
    ver: int = Field(...)


class RequestPayloadLoginParams(BaseModel):
    """
    Request payload login parameters
    """

    domain: str = Field(default="TOS")
    platform: str = Field(default="PROD")
    token: str = Field(...)
    accessToken: str = Field(default="")
    tag: str = Field(default="TOSWeb")


class RequestPayloadLogin(BaseModel):
    """
    Request payload login service
    """

    header: RequestPayloadHeader = Field(
        default=RequestPayloadHeader(service="login", id="login", ver=0)
    )
    params: RequestPayloadLoginParams = Field(...)


class RequestPayloadPositionsParams(BaseModel):
    """
    Request payload positions parameters
    """

    account: str = Field(default="COMBINED ACCOUNT")
    fields: List[str] = Field(default=["QUANTITY", "OPEN_PRICE", "OPEN_COST"])


class RequestPayloadOrdersParams(BaseModel):
    """
    Request payload orders parameters
    """

    account: str = Field(default="COMBINED ACCOUNT")
    types: List[str] = Field(default=["WORKING", "FILLED", "CANCELED"])


class RequestPayloadService(BaseModel):
    """
    Request payload service
    """

    header: RequestPayloadHeader = Field(...)
    params: Union[RequestPayloadPositionsParams, RequestPayloadOrdersParams] = Field(
        ...
    )


class RequestPayload(BaseModel):
    """
    Request payload data
    """

    payload: List[Union[RequestPayloadLogin, RequestPayloadService]] = Field(...)


if __name__ == "__main__":
    positions = RequestPayload(
        payload=[
            RequestPayloadService(
                header=RequestPayloadHeader(service="positions", id="positions", ver=0),
                params=RequestPayloadPositionsParams(),
            )
        ]
    )
    assert isinstance(positions.payload[0].params, RequestPayloadPositionsParams)
    orders = RequestPayload(
        payload=[
            RequestPayloadService(
                header=RequestPayloadHeader(
                    service="order_events", id="order_events", ver=0
                ),
                params=RequestPayloadOrdersParams(),
            )
        ]
    )
    assert isinstance(orders.payload[0].params, RequestPayloadOrdersParams)

EDIT2 当我有两个字段名称相同但类型不同的模型时，Alex 的解决方案不涵盖这种情况，如下所示：

class ResponseReplacePatchStr(BaseModel):
    op: str = Field(default="replace")
    path: str = Field(...)
    value: str = Field(...)

    class Config:
        extra = "forbid"

class ResponseReplacePatchFloat(BaseModel):
    op: str = Field(default="replace")
    path: str = Field(...)
    value: float = Field(...)

    class Config:
        extra = "forbid"

如果 ResponseReplacePatchStr 是

中提到的第一个类型，则 value 字段总是转换为类型 str

Union[
            ResponseReplacePatchStr, ResponseReplacePatchFloat
        ]

我怎样才能解决这个问题，让 Pydantic 照顾我的类型？

Answer 1

这是 Pydantic 匹配的功能之一 Union，即 described 如：

However, as can be seen above, pydantic will attempt to 'match' any of the types defined under Union and will use the first one that matches.[...]

As such, it is recommended that, when defining Union annotations, the most specific type is included first and followed by less specific types.

同时，默认情况下会忽略额外的字段，并在您的案例中使用声明字段的默认值。

因此，解决方案可能是添加 extra = 'forbid' 模型 config 选项：

class RequestPayloadPositionsParams(BaseModel):
    """
    Request payload positions parameters
    """
    account: str = Field(default="COMBINED ACCOUNT")
    fields: List[str] = Field(default=["QUANTITY", "OPEN_PRICE", "OPEN_COST"])

    class Config:
        extra = 'forbid'



class RequestPayloadOrdersParams(BaseModel):
    """
    Request payload orders parameters
    """
    account: str = Field(default="COMBINED ACCOUNT")
    types: List[str] = Field(default=["WORKING", "FILLED", "CANCELED"])

    class Config:
        extra = 'forbid'

Pydantic 对我的类型和他们的联合感到困惑

Pydantic is confused with my types and their union

python

types

pydantic