[guest@localhost testflaskapp]$ cat app.py 

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

import pgsqlconn

app = Flask(__name__)

@app.route('/')
def index():
    return render_template('index.html', title="Index")

@app.route('/db')
def get_database_data():
    data = pgsqlconn.get_data()
    return render_template('database.html', title="Database", data=data)

@app.route('/dbupdate', methods=['POST'])
def update_database_data():
    message = request.form['record']
    if message:
        data = pgsqlconn.get_data()
        number = len(data) + 1
        pgsqlconn.append_data(number, message)
    return redirect(url_for('get_database_data'))

@app.route('/dbclean')
def clean_database():
    pgsqlconn.clean_all_data()
    return redirect(url_for('get_database_data'))
[guest@localhost testflaskapp]$

[guest@localhost testflaskapp]$ cat pgsqlconn.py 
#!/usr/bin/env python3

import psycopg2

def get_data():
    conn = psycopg2.connect(
        host='hostname.amazonaws.com',
        port='5432',
        dbname='databasename',
        user='username',
        password='password'
                 'password')
    conn.set_client_encoding('utf-8')
    cur = conn.cursor()
    cur.execute('select * from tab')
    out = cur.fetchall()
    conn.close()
    return out

def append_data(number, message):
    conn = psycopg2.connect(
        host='hostname.amazonaws.com',
        port='5432',
        dbname='databasename',
        user='username',
        password='password'
                 'password')
    conn.set_client_encoding('utf-8')
    cur = conn.cursor()
    cur.execute("insert into tab values (%s, %s)", (number, message))
    conn.commit()
    conn.close()
    return True

def clean_all_data():
    conn = psycopg2.connect(
        host='hostname.amazonaws.com',
        port='5432',
        dbname='databasename',
        user='username',
        password='password'
                 'password')
    cur = conn.cursor()
    cur.execute("delete from tab")
    conn.commit()
    conn.close()
    return True

def main():
    print(get_data())

if __name__ == '__main__':
    main()
[guest@localhost testflaskapp]$

 @route('/')
@route('/index.html')
def index():
    return "<a href='/hello'>Go to Hello World page</a>"