Problem with uploading files

[ghada aissa]

I'm new to flask and i am trying to upload files i have as attributes filename data and ext(meaning extension of the file) this is my app.py code :

import base64

from fileinput import filename

from io import BytesIO

from optparse import Values

import string

from typing import Any

from flask_cors import CORS, cross_origin

from flask import Flask , render_template, request , send_file, jsonify

from flask_sqlalchemy import SQLAlchemy

from flask_restful import Api, Resource, reqparse

from werkzeug.utils import secure_filename

import os

app= Flask(__name__)

CORS(app)

app.config['SQLALCHEMY_DATABASE_URI']='sqlite:///data.db'

app.config['SQLALCHEMY_TRACK_MODIFICATIONs'] = False

db = SQLAlchemy(app)

api = Api(app)

app.secret_key = "caircocoders-ednalan"

UPLOAD_FOLDER = 'static/uploads'

app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER

app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 * 1024

ALLOWED_EXTENSIONS = set(['txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif', 'docx', 'pptx' , 'xlsx'])

def allowed_file(filename):

    return '.' in filename and filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS

class Upload(db.Model):

    id=db.Column(db.Integer, primary_key=True)

    filename = db.Column(db.String(50))

    data = db.Column(db.LargeBinary)

    ext = db.Column(db.String(50))

    def __init__(self, filename, data, ext):

        self.filename = filename

        self.ext = ext

   

    def json(self):

        return {"id":self.id , "filename":self.filename , "ext":self.ext }

@app.route('/upload' , methods=['POST'])

def upload_file():

    # check if the post request has the file part

    if 'files[]' not in request.files:

        resp = jsonify({'message' : 'No file part in the request'})

        resp.status_code = 400

        return resp

    files = request.files.getlist('files[]')

    errors = {}

    success = False

    for file in files:      

        if file and allowed_file(file.filename):

            filename = secure_filename(file.filename)

            ext = os.path.splitext(filename)

            file.ext = ext[1]

            file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))

            success = True

            upload = Upload(filename=file.filename, ext=file.ext, data=base64.b64encode(file.read()))

            db.session.add(upload)

            db.session.commit()

            return f'Uploaded: {file.ext}'

        else:

            errors[file.filename] = 'File type is not allowed'

    if success and errors:

        errors['message'] = 'File(s) successfully uploaded'

        resp = jsonify(errors)

        resp.status_code = 500

        return resp

    if success:

        upload = Upload(filename=file.filename, ext=file.ext, data=base64.b64encode(file.read()))

        db.session.add(upload)

        db.session.commit()

        """return f'Uploaded: {file.filename}'"""

        resp = jsonify({'message' : 'Files successfully uploaded'})

        resp.status_code = 201

        return resp

    else:

        resp = jsonify(errors)

        resp.status_code = 500

        return resp

when I try to upload a file I get the success message but when i check my DB i get the file as null 
I'm lost any help would be much appreciated 

thank you!