在基本模型中包含Pydantic的特殊字符

Question

我正在尝试创建一个Pydantic基本模型，其中包含一个'$'符号。它看起来像这样:

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

则得到SyntaxError: invalid syntax。但我需要保留密钥名称$something，以便在其他部分使用。在这种情况下，有没有一种允许使用美元符号的方法?

Answer 1

您可以使用Field(alias=...)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None的默认值，因为您在代码中有它。

这是一个工作示例(编辑:更新以显示如何获得您的变量名的别名，如果您需要以后使用它):

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)

如果你运行代码，然后发送一个POST正文:

{"$something": "bar"}

你会看到这样的内容:

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