问如何返回保存在数据库中的图片(Flask)

EN

@app.route('/upload', methods=['GET','POST'])
@login_required
def upload():
        
    if request.method == "POST":

        if not allowed_image_size(request.cookies.get("filesize")):
            return redirect(request.url)

        file = request.files['image']
        comentaries = request.form['comentaries']

        if not allowed_image(file.filename):
            return('No valid extencion')
            #return redirect(request.url
        else: 
            filename = secure_filename(file.filename)

        newFile = FileContent(client_name=current_user.username, comments=comentaries, data=file.read())
        db.session.add(newFile)
        db.session.commit() 
        return 'Saved ' + file.filename + ' to the database'    
    return render_template('upload.html')

@app.route('/download')
def download():
    file_data = FileContent.query.all()
    return send_file(BytesIO(file_data.data), attachment_filname='egreso.jpg', as_attachment=True)