server.py

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


@app.route('/')
def home():
    return render_template('index.html')


@app.route('/<string:page_name>')
def index(page_name):
    return render_template(page_name)


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


def write_to_csv(data):
    with open('database.csv', newline='', mode='a') as database2:
        name = data['name']
        email = data['email']
        subject = data['subject']
        message = data['message']
        if email and subject and message and name != '':
            csv_writer = csv.writer(database2, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL)
            csv_writer.writerow([name, email, subject, message])


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

        try:
            data = request.form.to_dict()
            write_to_csv(data)
            return redirect('/thank_you.html')
        except:
            return 'Wasn\'t saved to database'
    else:
        return 'something went wrong'