FastAPI Web框架 [Pydantic]

Posted 2022-06-18 weixin_45253622

学习一下，做个记录。

Starlette，Pydantic 与 FastAPI 的关系

• Python 的类型提示 type hints
• Pydantic 是一个基于 Python 类型提示来定义数据验证，序列化和文档（使用JSON 模式）库。
• Starlette 是一种轻量级的 ASGI 框架/工具包，是构建高性能 Asyncio 服务的理想选择。
  

from datetime import datetime,date
from pydantic import BaseModel,ValidationError, constr
from pathlib import Path
from typing import List, Optional

from sqlalchemy import Column, Integer, String      #ORM
from sqlalchemy.dialects.postgresql import ARRAY
from sqlalchemy.ext.declarative import declarative_base

class User(BaseModel):
    id: int     #必填字段
    name: str = "John Snow"     #有默认值，选填字段
    signup_ts: Optional[datetime] = None    #有默认值，选填字段
    friends: List[int] = []     # 列表中的元素是int类型或者可以直接转换为int类型

external_data = 
    "id": "123",
    "signup_ts": "2022-6-16 11:15",
    "friends": [1,2,"3"]


user = User(**external_data)
print(user.name,user.friends)       # 实例化后调用属性
print(repr(user.signup_ts))         # repr() 函数将对象转化为供解释器读取的形式。
print(user.dict())

try:
    User(id=1, signup_ts=datetime.today(), friends=[1,2,"not number"])
except ValidationError as e:
    print(e.json())


print(user.dict())
print(user.json())
print(user.copy())      # 浅拷贝
print(User.parse_obj(obj=external_data))
print(User.parse_raw('"id": 123, "name": "John Snow1", "signup_ts": "2022-06-16T11:15:00", "friends": [1, 2, 3]'))

path = Path('pydantic_test.json')
path.write_text('"id": 123, "name": "John Snow1", "signup_ts": "2022-06-16T11:15:00", "friends": [1, 2, 3]')
print(User.parse_file(path))

print(user.schema())
print(user.schema_json())

user_data = "id": "error", "name": "John Snow1", "signup_ts": "2022-06-16T11:15:00", "friends": [1, 2, 3]
print(User.construct(**user_data))      #construct()不校验数据直接创建模型类，不建议在construct方法中传入未经验证的数据

print(User.__fields__.keys())       #查看所有字段，定义模型类的时候，所有字段都注明类型，字段顺序就不会乱

class Sound(BaseModel):
    sound: str

class Dog(BaseModel):
    birthday: date
    weight: float = Optional[None]
    sound: List[Sound]      #不同的狗有不同的叫声。递归模型（Recursive Models）就是指一个嵌套一个

dogs = Dog(birthday=date.today(), weight=6.66, sound=[
    "sound": "wang wang",
    "sound": "ying ying"
])
print(dogs.dict())

Base = declarative_base()

class CompanyOrm(Base):
    __tablename__ = 'companies'         #表名
    id = Column(Integer, primary_key=True, nullable=False)      #主键，不能为空
    public_key = Column(String(20), index=True, nullable=False, unique=True)
    name = Column(String(63), unique=True)
    domains = Column(ARRAY(String(255)))

class CompanyMode(BaseModel):
    id: int
    public_key: constr(max_length=20)
    name: constr(max_length=63)
    domains: List[constr(max_length=255)]

    class Config:
        orm_mode = True

# 数据表模型类的实例
co_orm = CompanyOrm(
    id = 123,
    public_key = 'forbar',
    name = 'Testing',
    domains = ['example.com', 'test.com']
)
print(CompanyMode.from_orm(co_orm))

学习：https://www.bilibili.com/video/BV1iN411X72b?p=7&spm_id_from=pageDriver&vd_source=06af20c53d413fe5fafd741f14bacbf1