在 Pydantic 的 Basemodel 中包含特殊字符

Question

我正在尝试使用包含“$”符号的键创建一个 Pydantic 基础模型。它看起来像这样：

class someModel(BaseModel):
    $something:Optional[str] = None

然后我得到SyntaxError: invalid syntax。但是我需要保留键名 $something 以便在其他部分使用。在这种情况下有没有办法允许美元符号？

Answer 1

您可以使用 Field(alias=...) 来使用不同的（有效的）变量名。

from pydantic import BaseModel, Field

class SomeModel(BaseModel):
    something: Optional[str] = Field(alias="$something", default=None)

我还添加了一个默认值 None，因为您的代码中有它。

这是一个工作示例（编辑：已更新以显示如何获取变量名称的别名，如果您以后需要使用它）：

import logging
from typing import Optional
from fastapi import FastAPI, Request
from pydantic import BaseModel, Field

logging.basicConfig(level=logging.INFO, format="%(levelname)-9s %(asctime)s - %(name)s - %(message)s")
LOGGER = logging.getLogger(__name__)

app = FastAPI()


class SomeModel(BaseModel):
    something: Optional[str] = Field(alias="$something", default=None)


@app.post("/")
async def root(request: Request, parsed_body: SomeModel):

    # A dict of all the model fields and their properties
    LOGGER.info(f"SomeModel.__fields__: {SomeModel.__fields__}")

    # To get the alias of the variable name
    something_alias = SomeModel.__fields__["something"].alias
    LOGGER.info(f"something_alias: {something_alias}")

    # Edit: prefer to use "parsed_body_by_alias" than raw_body. Leaving here to show the difference.
    raw_body: bytes = await request.body()
    LOGGER.info(f"raw_body: {raw_body}")

    # Edit: This is better as you get validated / parsed values, including defaults if applicable.
    parsed_body_by_alias = parsed_body.dict(by_alias=True)
    LOGGER.info(f"parsed_body_by_alias: {parsed_body_by_alias}")

    # If you just want "something" instead of "$something"
    LOGGER.info(f"parsed_body: {parsed_body}")
    LOGGER.info(f"parsed_body.something: {parsed_body.something}")

    return 1


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app, host="127.0.0.1", port=8080)

如果您运行代码然后发送 POST 正文：

{"$something": "bar"}

您会看到如下内容：

INFO      xxx - __main__ - SomeModel.__fields__: {'something': ModelField(name='something', type=Optional[str], required=False, default=None, alias='$something')}
INFO      xxx - __main__ - something_alias: $something
INFO      xxx - __main__ - raw_body: b'{"$something": "bar"}'
INFO      xxx - __main__ - parsed_body_by_alias: {'$something': 'bar'}
INFO      xxx - __main__ - parsed_body: something='bar'
INFO      xxx - __main__ - parsed_body.something: bar
INFO:     127.0.0.1:xxxxx - "POST / HTTP/1.1" 200 OK

在 Pydantic 的 Basemodel 中包含特殊字符

Including special character in Basemodel for Pydantic

python

pydantic

fastapi