server.py

import csv
from flask import Flask,redirect, render_template, request
app = Flask(__name__) # 

@app.route('/')
def main():
    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('database.txt', mode='a') as database:
        email = data["email"]
        subject = data["subject"]
        message = data["message"]
        data_to_file = database.write(f'\n{email},{subject},{message}')


def write_to_csv(data):
    with open('database.csv', '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.writeheader
        csv_writer.writerow([email,subject,message])


@app.route('/submit_form', methods=['POST', 'GET'])
def submit_form():

 
    if request.method == 'POST':
        data = request.form.to_dict()
        print(data)
        write_to_csv(data)
        return redirect('/thankyou.html')
    else:
        return 'error! '