# 傳統(tǒng)驗(yàn)證的噩夢(mèng)代碼片段
def create_user(data: dict):
    if 'name' not in data:
        raise ValueError("Missing name")
    if len(data['name']) > 20:
        raise ValueError("Name too long")
    if 'email' not in data:
        raise ValueError("Missing email")
    if not re.match(r"[^@]+@[^@]+\.[^@]+", data['email']):
        raise ValueError("Invalid email")
    # 此處省略20個(gè)字段驗(yàn)證...

from pydantic import BaseModel, EmailStr

class UserCreateRequest(BaseModel):
    name: str  # 自動(dòng)識(shí)別為必填字段！
    email: EmailStr  # 自帶郵箱格式核武器
    age: int = 18  # 默認(rèn)值這么寫太優(yōu)雅了吧？

# 正確數(shù)據(jù)
user_data = {"name": "張三", "email": "zhangsan@example.com"}
user = UserCreateRequest(**user_data)  # 自動(dòng)驗(yàn)證并轉(zhuǎn)換類型！

# 錯(cuò)誤數(shù)據(jù)
bad_data = {"name": "李四", "email": "lisi#wrong.com"}
user = UserCreateRequest(**bad_data)  # 自動(dòng)拋出ValidationError！

{
  "detail": [
    {
      "loc": ["email"],
      "msg": "value is not a valid email address",
      "type": "value_error.email"
    }
  ]
}

from datetime import datetime
from pydantic import HttpUrl, PositiveInt

class Product(BaseModel):
    id: PositiveInt  # 自動(dòng)拒絕負(fù)數(shù)！
    url: HttpUrl      # 自動(dòng)驗(yàn)證URL格式
    created_at: datetime  # 自動(dòng)把字符串轉(zhuǎn)成datetime對(duì)象

from pydantic import validator

class UserProfile(BaseModel):
    username: str
    
    @validator('username')
    def name_must_contain_letter(cls, v):
        if not any(char.isalpha() for char in v):
            raise ValueError('必須包含字母！')
        return v

from fastapi import FastAPI

app = FastAPI()

@app.post("/users")
def create_user(user: UserCreateRequest):  # 此處自動(dòng)完成驗(yàn)證！
    # 直接使用user.name, user.email等強(qiáng)類型屬性
    return {"message": f"用戶{user.name}創(chuàng)建成功"}

# 錯(cuò)誤示范（時(shí)區(qū)炸彈?。?
birthday: datetime  # 可能引發(fā)時(shí)區(qū)混亂

# 正確姿勢(shì)
from datetime import datetime
from pydantic import AwareDatetime

birthday: AwareDatetime  # 強(qiáng)制要求帶時(shí)區(qū)

class Config:
    # 開啟這個(gè)讓解析速度飛起！
    anystr_strip_whitespace = True  
    
    # 禁止多余字段（防惡意傳參?。?
    extra = 'forbid'  

from pydantic import Field

class Payment(BaseModel):
    amount: float = Field(..., gt=0, description="支付金額必須為正數(shù)") 
    card_id: str = Field(..., min_length=16, max_length=19)

# 基礎(chǔ)模型
class UserBase(BaseModel):
    email: EmailStr

# 創(chuàng)建專用
class UserCreate(UserBase):
    password: str

# 響應(yīng)專用（隱藏密碼字段）
class UserResponse(UserBase):
    id: int

# SQLAlchemy模型
class UserModel(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String(50))

# Pydantic模型
class UserResponse(BaseModel):
    id: int
    name: str

    # 添加這個(gè)配置實(shí)現(xiàn)自動(dòng)轉(zhuǎn)換！
    class Config:
        orm_mode = True  # 魔法開關(guān)?。。?

# 使用示例
db_user = session.query(UserModel).first()
response_data = UserResponse.from_orm(db_user)  # 自動(dòng)轉(zhuǎn)換！

from pydantic import SecretStr

class LoginRequest(BaseModel):
    username: str
    password: SecretStr  # 自動(dòng)屏蔽日志輸出！??！

# 使用時(shí)
print(request.password)  # 輸出：**********
real_pwd = request.password.get_secret_value()  # 獲取真實(shí)值

@app.post("/login")
def login(credentials: LoginRequest):
    ...