FastAPI to upload .csv and write into Database

csv.py

import csv
import io
from fastapi import FastAPI, File, UploadFile, HTTPException
from sqlalchemy import create_engine, Column, Integer, String, Float, ForeignKey
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import declarative_base, relationship, sessionmaker

# Datenbankkonfiguration
DATABASE_URL = "sqlite:///./sensordaten.db"
engine = create_engine(DATABASE_URL)
Base = declarative_base()

# Tabellen
class Sensor(Base):
    __tablename__ = "sensors"
    id = Column(Integer, primary_key=True)
    sensor_id = Column(String, unique=True)
    measurements = relationship("Measurement", back_populates="sensor")


class Measurement(Base):
    __tablename__ = "measurements"
    id = Column(Integer, primary_key=True)
    sensor_id = Column(Integer, ForeignKey("sensors.id"))
    timestamp = Column(String)
    humidity = Column(Float)
    sensor = relationship("Sensor", back_populates="measurements")


# Tabellen erstellen
Base.metadata.create_all(bind=engine)

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

app = FastAPI()


@app.post("/uploadcsv/")
async def upload_csv(file: UploadFile = File(...)):
    if file.content_type != "text/csv":
        raise HTTPException(status_code=400, detail="File must be in CSV format.")

    content = (await file.read()).decode("utf-8")
    csvfile = csv.reader(io.StringIO(content), delimiter=",")

    session = SessionLocal()
    try:
        for row in csvfile:
            sensor_id, timestamp, humidity = row

            sensor = session.query(Sensor).filter(Sensor.sensor_id == sensor_id).first()
            if not sensor:
                sensor = Sensor(sensor_id=sensor_id)
                session.add(sensor)
                session.flush()

            measurement = Measurement(sensor_id=sensor.id, timestamp=timestamp, humidity=float(humidity))
            session.add(measurement)
            session.flush()

        session.commit()
    except Exception as e:
        session.rollback()
        raise HTTPException(status_code=400, detail=str(e))
    finally:
        session.close()

    return {"status": "success"}


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="127.0.0.1", port=8000)