Pydantic中serialization_alias的实现

# 简化版序列化别名处理逻辑
def get_serialization_key(field: FieldInfo, by_alias: bool) -> str:
    if by_alias:
        if field.serialization_alias is not None:
            return field.serialization_alias
        elif field.alias is not None:
            return field.alias
    return field.name

from pydantic import BaseModel, Field

class User(BaseModel):
    first_name: str = Field(serialization_alias='firstName')  # 蛇形→驼峰
    last_name: str = Field(serialization_alias='lastName')
    email_address: str = Field(serialization_alias='email')  # 长名→短名

# 序列化时启用别名
user = User(first_name='John', last_name='Doe', email_address='john@example.com')
print(user.model_dump())  # 默认输出原始字段名
#> {'first_name': 'John', 'last_name': 'Doe', 'email_address': 'john@example.com'}

print(user.model_dump(by_alias=True))  # 启用别名输出
#> {'firstName': 'John', 'lastName': 'Doe', 'email': 'john@example.com'}

print(user.model_dump_json(by_alias=True))  # JSON序列化同样生效
#> {"firstName":"John","lastName":"Doe","email":"john@example.com"}

from pydantic import BaseModel, Field

class Product(BaseModel):
    # 输入：兼容API v1的product_id和v2的id；输出：统一为productId
    id: int = Field(
        validation_alias=AliasChoices('id', 'product_id'),  # 多输入别名
        serialization_alias='productId'  # 统一输出别名
    )
    # 输入：蛇形命名；输出：帕斯卡命名
    unit_price: float = Field(serialization_alias='UnitPrice')
    # 输入输出保持一致（无别名）
    stock_count: int

# 解析v1版本数据
product_v1 = Product.model_validate({'product_id': 123, 'unit_price': 99.9, 'stock_count': 100})
# 解析v2版本数据
product_v2 = Product.model_validate({'id': 456, 'unit_price': 199.9, 'stock_count': 50})

# 统一输出格式
print(product_v1.model_dump(by_alias=True))
#> {'productId': 123, 'UnitPrice': 99.9, 'stock_count': 100}
print(product_v2.model_dump(by_alias=True))
#> {'productId': 456, 'UnitPrice': 199.9, 'stock_count': 50}

from pydantic import BaseModel, ConfigDict, Field

class BaseAPIModel(BaseModel):
    model_config = ConfigDict(
        alias_generator=lambda field_name: field_name.title().replace('_', ''),  # 全局转帕斯卡命名
        serialize_by_alias=True,  # 模型级别默认启用序列化别名
        validate_by_name=True  # 模型级别同时支持字段名和别名验证
    )

class User(BaseAPIModel):
    first_name: str  # 使用全局别名生成器→FirstName
    last_name: str   # 使用全局别名生成器→LastName
    email: str = Field(serialization_alias='EMail')  # 局部覆盖→EMail

user = User(first_name='Alice', last_name='Smith', email='alice@example.com')
print(user.model_dump())  # 无需by_alias=True，模型配置已启用
#> {'FirstName': 'Alice', 'LastName': 'Smith', 'EMail': 'alice@example.com'}

# FastAPI示例：后端蛇形命名→前端驼峰命名
from fastapi import FastAPI
from pydantic import BaseModel, Field

app = FastAPI()

class UserIn(BaseModel):  # 输入模型：兼容多种命名
    user_name: str = Field(validation_alias=AliasChoices('user_name', 'username', 'userName'))
    user_age: int = Field(validation_alias=AliasChoices('user_age', 'age'))

class UserOut(BaseModel):  # 输出模型：严格驼峰命名
    user_name: str = Field(serialization_alias='userName')
    user_age: int = Field(serialization_alias='userAge')
    is_active: bool = Field(serialization_alias='isActive')

@app.post("/users", response_model=UserOut)
def create_user(user: UserIn) -> UserOut:
    # 业务逻辑处理...
    return UserOut(**user.model_dump())  # 自动完成命名转换

from pydantic import BaseModel, Field, field_serializer

class Model(BaseModel):
    value: int = Field(serialization_alias='FormattedValue')
    
    @field_serializer('value')
    def serialize_value(self, v) -> str:
        return f"${v:,}"  # 序列化时同时格式化值

m = Model(value=1000)
print(m.model_dump(by_alias=True))  # {'FormattedValue': '$1,000'}

class BaseResponse(BaseModel):
    model_config = ConfigDict(serialize_by_alias=True)
    status: str = Field(serialization_alias='Status')
    code: int = Field(serialization_alias='Code')

class DataResponse(BaseResponse):
    data: dict = Field(serialization_alias='Data')  # 自动继承序列化配置