如何从蛇案例转变为骆驼案例 post pydantic 模式验证

Question

我可以找到一种方法，使用 Alias Generator 将基于 camelcase 类型的请求正文转换为 snake case one，但是对于我的响应，我再次想将 snake case 类型转换为 camel case 类型 post到架构验证。有什么办法可以实现吗？

示例：我确实有一个 python 字典，如下所示，

{
 "title_name": "search001",
 "status_type": "New" 
}

并且 post 到 pydantic 模式验证我的字典应该将蛇形大小写类型转换为驼峰大小写，如下所示，

{
 "titleName": "search001",
 "statusType": "New" 
}

如何定义一个 pydantic 模式来解决上述问题？

提前致谢。

Answer 1

我强烈推荐你可以试试 this.Using marshmallow.

from marshmallow import Schema, fields


def camelcase(s):
    parts = iter(s.split("_"))
    return next(parts) + "".join(i.title() for i in parts)


class CamelCaseSchema(Schema):
    """Schema that uses camel-case for its external representation
    and snake-case for its internal representation.
    """

    def on_bind_field(self, field_name, field_obj):
        field_obj.data_key = camelcase(field_obj.data_key or field_name)


# -----------------------------------------------------------------------------


class UserSchema(CamelCaseSchema):
    first_name = fields.Str(required=True)
    last_name = fields.Str(required=True)


schema = UserSchema()
loaded = schema.load({"firstName": "David", "lastName": "Bowie"})
print(loaded)  # => {'last_name': 'Bowie', 'first_name': 'David'}
dumped = schema.dump(loaded)
print(dumped)  # => {'lastName': 'Bowie', 'firstName': 'David'}

您可以在文档中了解更多信息 https://marshmallow.readthedocs.io/en/stable/examples.html

Answer 2

您可以使用Alias Generator

from pydantic import BaseModel


def to_snake_case(string: str) -> str:
    return ''.join(['_' + i.lower() if i.isupper() else i for i in string]).lstrip('_')


class MyModel(BaseModel):
    titleName: str
    statusType: str

    class Config:
        alias_generator = to_snake_case


data = {
    "title_name": "search001",
    "status_type": "New"
}
print(MyModel(**data).dict()) # {'titleName': 'search001', 'statusType': 'New'}

Answer 3

您可以在 .json 或 .dict:

中结合使用别名生成器和 kwarg by_alias

from pydantic import BaseModel,Field

def to_camel(string: str) -> str:
    string_split = string.split('_')
    return string_split[0]+''.join(word.capitalize() for word in string_split[1:])


class Foo(BaseModel):
    title_name:str
    status_type:str
    class Config:
        alias_generator = to_camel

f = Foo.parse_raw("""
{
 "titleName": "search001",
 "statusType": "New" 
}
""")
print(f) # title_name='search001' status_type='New'
print(f.json(by_alias=True)) # {"titleName": "search001", "statusType": "New"}
print(f.json()) # {"title_name": "search001", "status_type": "New"}

另外，你可以在Config中加上allow_population_by_field_name=True class 这样你就可以parse/initialize model 的原始字段名或别名

Answer 4

如果您使用的是 fastapi，则可以按如下方式利用 fastapi_camelcase 包：

import uvicorn
from fastapi import FastAPI
from fastapi_camelcase import CamelModel


class User(CamelModel):
    first_name: str
    last_name: str
    age: int


app = FastAPI()


@app.get("/user/get", response_model=User)
async def get_user():
    return User(first_name="John", last_name="Doe", age=30)


@app.post("/user/create", response_model=User)
async def create_user(user: User):
    return user


if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8000)

如何从蛇案例转变为骆驼案例 post pydantic 模式验证

How to inflect from snake case to camel case post the pydantic schema validations

python

pydantic