server.py

from flask import Flask,render_template,request,redirect 
import csv

app = Flask(__name__)

@app.route("/")                                         #This is the default root of the server
def home():
    return render_template('index.html')

@app.route("/<string:page_name>")                                       
def html_page(page_name):
    return render_template(page_name)

def write_to_file(data):
    with open('./Portfolio/database.txt', mode='a') as database:
        email = data['email']
        subject = data['subject']
        message = data['message']
        file = database.write(f'\n{email},{subject},{message}')

def write_to_csv(data):
    with open('./Portfolio/database.csv', mode='a', newline='') as database2:
        email = data['email']
        subject = data['subject']
        message = data['message']
        csv_writer = csv.writer(database2, delimiter=' ',quotechar='|', quoting=csv.QUOTE_MINIMAL)
        csv_writer.writerow([email,subject,message])

@app.route("/submit_form" , methods=['POST','GET'])                                      
def sub_form():
    if request.method=='POST':
        data = request.form.to_dict()
        write_to_csv(data)
        return redirect ('/thankyou.html')
    else:
        return 'Something went wrong. Try again!!!'