Pydantic模型继承解析：从字段继承到多态模型

from pydantic import BaseModel


class UserBase(BaseModel):
    email: str
    is_active: bool = True


class UserCreate(UserBase):
    password: str  # 新增字段
    is_active: bool = False  # 覆盖父类默认值


# 验证示例
user = UserCreate(email="test@example.com", password="secret")
print(user.is_active)  # 输出: False

from pydantic import Field


class StrictUser(UserBase):
    email: str = Field(..., regex=r"^[\w\.]+@[a-zA-Z]+\.[a-zA-Z]+$")
    age: int = Field(ge=18, lt=100)  # 新增约束字段

class ConfigBase(BaseModel):
    timeout: int = 10
    retries: int = 3


class ProductionConfig(ConfigBase):
    timeout: int = 30  # 覆盖默认值
    log_level: str = "ERROR"  # 新增字段

class PaymentBase(BaseModel):
    amount: float


class StrictPayment(PaymentBase):
    amount: confloat(gt=0)  # 强化类型约束

from pydantic import Field


class Animal(BaseModel):
    type: str = Field(..., alias="_type")


class Cat(Animal):
    _type: str = "cat"
    lives: int


class Dog(Animal):
    _type: str = "dog"
    breed: str


def parse_animal(data: dict) -> Animal:
    type_map = {
        "cat": Cat,
        "dog": Dog
    }
    return type_map[data["_type"]](**data)

from pydantic import create_model

DynamicModel = create_model(
    'DynamicModel',
    __base__=UserBase,
    role=(str, Field(regex="^(admin|user)$"))
)

class Parent(BaseModel):
    class Config:
        extra = "forbid"
        anystr_strip_whitespace = True


class Child(Parent):
    class Config(Parent.Config):
        validate_assignment = True

from pydantic import BaseModel, Extra


class FlexibleModel(BaseModel):
    class Config:
        extra = Extra.allow


StrictModel = type(
    'StrictModel',
    (FlexibleModel,),
    {'Config': type('Config', (FlexibleModel.Config,), {'extra': Extra.ignore})}
)

class TimestampMixin(BaseModel):
    created_at: datetime = Field(default_factory=datetime.now)
    updated_at: datetime = Field(default_factory=datetime.now)


class UserWithTime(TimestampMixin, UserBase):
    pass

def create_model_with_extra_fields(base: Type[BaseModel], **fields):
    return create_model(
        f'Extended{base.__name__}',
        __base__=base,
        **fields
    )


ExtendedUser = create_model_with_extra_fields(
    UserBase,
    phone=(str, Field(regex=r"^1[3-9]\d{9}$"))
)

try:
    class InvalidModel(UserBase):
        email: int  # 类型冲突
except TypeError as e:
    print(f"继承错误: {e}")

def print_model_fields(model: Type[BaseModel]):
    for name, field in model.__fields__.items():
        print(f"{name}: {field.type_} (default={field.default})")


print_model_fields(StrictPayment)