Fluent Alchemy

輕鬆流暢地使用 SQLAclhemy

• Installation
• Quick start
• Features
• Mixins
• Examples

Installation

pip insall fluent-alchemy

Quick start

1. 宣告 Models 並繼承 ActiveRecord

# models.py
from sqlalchemy.orm import DeclarativeBase
from fluent_alchemy import ActiveRecord

class Base(DeclarativeBase, ActiveRecord):
    pass

class User(Base):
    __tablename__ = "users"

    id: Mapped[int] = mapped_column(BigInteger(), primary_key=True)
    email: Mapped[str] = mapped_column(String(), unique=True)
    password: Mapped[str] = mapped_column(String())
    name: Mapped[str] = mapped_column(String(50))
    state: Mapped[bool] = mapped_column(Boolean())

2. 建立 SQLAclhemy Engine, 並指派給 ActiveRecord 內的 session handler

from sqlalchemy import create_engine
from models import Base

engine = create_engine("sqlite://:memory:", echo=True)

Base.set_engine(engine)

3. 開始使用 model 操作 database !

from models import User

users = User.all()

4. 使用完畢後，釋放 Session 資源

from models import Base

Base.remove_scoped_session()

Features

Active Record

利用 QueryBuilder 來處理 SQLAlchemy 的 select() query statement

• Create

  from models import User
  
  user = User.create(
      name="Justin",
      email="corey97@example.org",
      password="NioWe9Wn#+"
  )
  
  # or
  
  user = User(
      name="Justin",
      email="corey97@example.org",
      password="NioWe9Wn#+"
  )
  user.save()
  

• Read

  1. Find by id

     user = User.find(1)
     

  2. 只回傳特定欄位

     user = User.select(User.id, User.name, User.email).first()
     

  3. 透過 where 增加查詢條件

     user = User.where(User.email == "corey97@example.org").first()
     

     users = User.where(User.state.is_(True)).get()
     

• Update

  user = User.find(1)
  user.passwod = "6xjVAY$p&D"
  
  user.save()
  

• Delete

  user = User.find(1)
  user.delete()
  

• Pagenate

  # setting page number and rows count per page
  pagination = User.paginate(page=1, per_page=15)
  
  """
  {
      "total": 100,
      "per_page": 15,
      "current_page": 1,
      "last_page": 7,
      "data": [ ... ], # ussers
  }
  """
  

Mixins

TimestampMixin

讓指定的 Model class 繼承 TimestampMixin，讓該 Model 補上 created_at, updated_at 欄位。

from fluent_alchemy import ActiveRecord, TimestampMixin

class Base(DeclarativeBase, ActiveRecord):
    pass

class User(Base, TimestampMixin):
    __tablename__ = "users"
    ...

###
user = User.find(1)

print(user.created_at)
print(user.updated_at)

SoftDeleteMixin

讓指定的 Model class 繼承 SoftDeleteMixin，就可以讓該 Model 擁有 Soft delete 的能力。

from sqlalchemy.orm import DeclarativeBase
from fluent_alchemy import ActiveRecord, SoftDeleteMixin

class Base(DeclarativeBase, ActiveRecord):
    pass

class User(Base, SoftDeleteMixin):
    __tablename__ = "users"

    id: Mapped[int] = mapped_column(BigInteger(), primary_key=True)
    email: Mapped[str] = mapped_column(String(), unique=True)
    password: Mapped[str] = mapped_column(String())
    name: Mapped[str] = mapped_column(String(50))
    state: Mapped[bool] = mapped_column(Boolean())

SoftDeleteMixin 會自動補上 deleted_at 欄位，依此欄位來處理 soft delete 的資料。

deleted_at: Mapped[Optional[datetime]] = mapped_column(TIMESTAMP(), nullable=True)

設定完成後，之後對此 Model 進行 Query 時，會在 statement 內的 WHERE 條件自動加上 deleted_at IS NULL。

查詢已被標記刪除的資料

users_deleted = User.where(...).get(with_trashed=True)

強制刪除 (Force delete)

user = User.find(1)

user.delete(force=True)

Examples

在 FastAPI 內使用

from contextlib import asynccontextmanager
from fastapi import FastAPI, Depends
from app.models import BaseModel, User

def close_scoped_session():
    """
    Remove the scoped session at the enf of every request.
    """
    yield
    BaseModel.remove_scoped_session()

@asynccontextmanager
async def lifespan(app: FastAPI):
    """
    Set engine to the ScopedSessionHandler when FastAPI app started.
    """
    BaseModel.set_engine(engine)
    yield

app = FastAPI(
    title="MyApp",
    dependencies=[Depends(close_scoped_session)],
    lifespan=lifespan
)

@app.get("/users")
def index():
    return User.all()