<prompt> Unda seva ya Python FastAPI ambayo hutoa miisho ya shughuli za CRUD kwenye hifadhidata ya PostgreSQL. Tumia SQLAlchemy kwa ORM na uhakikishe uthibitishaji sahihi wa data inayoingia.PLINFORMAT  <response>: kutoka fastapi kuleta FastAPI, HTTPExceptionkutoka kwa pydantic import BaseModelkutoka kwa kuchapa Orodha ya kuingizakuagiza mifanokutoka kwa hifadhidata ya kuingiza SessionLocal, injiniapp FastAPImodel.Base.metadata.create_allbindinjiniclass ItemCreateBaseModel: jina: str maelezo: strclass ItemUpdateBaseModel: kitambulisho: int jina: str maelezo: response_modelmodels.Itemdef create_itemkitu: ItemCreate: db SessionLocal db_item model.Itemjinaitem.name, descriptionitem.description db.ongezadb_item db.commit db.refreshdb_item rudisha kipengee cha response_modelmodels.Itemdef read_itemitem_id: int: db SessionLocal item db.querymodels.Item.chujiomodels.Item.id item_id.kwanza ikiwa sio kitu: ongeza HTTPExceptionstatus_code404, detailsKipengee hakijapatikana kurejesha response_modelOrodhamodels.Itemdef read_items: db SessionLocal vitu db.querymodels.Item.all kurejesha response_modelmodels.Itemdef update_itemitem_id: int, item: ItemUpdate: db SessionLocal db_item db.querymodels.Item.chujiomodels.Item.id item_id.kwanza ikiwa sio db_item: ongeza HTTPExceptionstatus_code404, detailsKipengee hakijapatikana db_item.name item.name db_item.description item.description db.commit rudisha kipengee cha delete_itemitem_id: int: db SessionLocal item db.querymodels.Item.chujiomodels.Item.id item_id.kwanza ikiwa sio kitu: ongeza HTTPExceptionstatus_code404, detailsKipengee hakijapatikana db.futakipengee db.commit return detail: Kipengee kimefutwahifadhidata .pykutoka sqlalchemy import create_enginekutoka sqlalchemy.ext.declarative import declarative_basekutoka sqlalchemy.orm import sessionmakerDATABASE_URL postgresql:username:passwordlocalhostdbnameinjini create_engineDATABASE_URLSessionLocal mtayarishaji kikaoautocommitUongo, autoflushUongo, fungainjiniMsingi declarative_base mifano.pykutoka sqlalchemy kuagiza Safu, Integer, Stringkutoka kwa Msingi wa uagizaji wa hifadhidataKipengee cha darasa Msingi: __tablename__ vitu id Safu wimaNambari, ufunguo_msingiKweli, faharisiKweli jina Safu Kamba, faharisiKweli maelezo Safu wimaKamba 