Write Python Weather APP on Heroku(8)

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Deploy on Heroku

The deployed version is listed as following:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Set default encoding: utf-8
import sys;
reload(sys);
# Setting the utf-8 format
sys.setdefaultencoding("utf8")

import os
import logging
import string
from celery import Celery
from celery.task import periodic_task
from datetime import datetime,timedelta
from os import environ


# For retrieving temperature/humidity
import pywapi
import urllib2
from urllib2 import ProxyHandler
import re
from BeautifulSoup import BeautifulSoup

# For using database(Postgresql)
# from flash.ext.sqlalchemy import SQLAlchemy
from sqlalchemy import create_engine
from sqlalchemy import MetaData, Column, Table, ForeignKey
from sqlalchemy import Integer, String, DateTime


# redis configuration for celery
### Local, should be change to remote when deploying to heroku
# REDIS_URL = environ.get('REDISTOGO_URL', 'redis://localhost')
### Heroku Ways
REDIS_URL = environ.get('REDISCLOUD_URL')


celery = Celery('tasks', broker=REDIS_URL)

# Fetch 


# Define Periodic Tasks
@periodic_task(run_every=timedelta(minutes=60))
# Funciton for fetching data and store it in Postgres
def fetch_and_store_data():
    # Fetching the weather information from Yahoo. 
    Yahoo_Result = pywapi.get_weather_from_yahoo('CHXX0099')
    Current_Temp = string.lower(Yahoo_Result['condition']['temp'])
    Current_Humi = string.lower(Yahoo_Result['atmosphere']['humidity'])
    Tomorrow_Forecast = Yahoo_Result['forecasts'][0]
    Twenty_Four_Hours = Yahoo_Result['forecasts'][1]
    Fourty_Eight_Hours = Yahoo_Result['forecasts'][2]
    Seventy_Two_Hours = Yahoo_Result['forecasts'][3]
    # !!! comment proxy related for deploying to heroku !!! #
    # proxy = urllib2.ProxyHandler({'http': '1xx.x.xx.xxx:2xxx'})
    # opener = urllib2.build_opener(proxy)
    # urllib2.install_opener(opener)
    # !!! comment out end #
    page = urllib2.urlopen("http://www.pm25.in/nanjing")
    soup = BeautifulSoup(page)                      #
    # Find the detailed table from the soup.        #
    table = soup.find('table', {'id':'detail-data'})#
    # Fetch the XuanWuHu, if not, use MaiGaoQiao ins#tead. 
    rows = table.findAll('tr')                      #
    for subrows in rows:                            #
        if "玄武湖" in subrows.text:                #
            XuanwuLake = subrows                    #
        else:                                       #
            if "迈皋桥" in subrows.text:            #
                XuanwuLake = subrows                #
    XuanwuLake_subitem = XuanwuLake.findAll('td')   #
    # Here we will get an array, fetch out the text #for the content from this array.
    # Fetched origin data, different from cnpm25.cn #
    pm_25_orig = XuanwuLake_subitem[4].text         #
    pm_10_orig = XuanwuLake_subitem[5].text
    # Open the Database
    # Local Engine
    # engine = create_engine('postgresql+psycopg2://Trusty:@localhost:5432/mylocaldb',echo=True)
    # Heroku Engine
    db_conn = environ['DATABASE_URL']
    engine = create_engine(db_conn)

    metadata=MetaData(bind=engine)
    
    # Definition of the weather table
    weather_table=Table('weather',metadata,
    	Column('Insert_Time', DateTime(timezone=True),primary_key=True),
    	Column('Temperature', Integer),
    	Column('Humidity', Integer),
    	Column('PmTen', Integer),
    	Column('PmTwoFive', Integer),
    )

    # Create the table in mylocaldb
    metadata.create_all(checkfirst=True)

    # Record Insertion
    # First generate an insertion sentense:
    ins = weather_table.insert()
    # Really insert into the Database
    # ins = weather_table.insert().values(Insert_Time=datetime.datetime.utcnow(), Temperature=25, Humidity=75, PmTen=100, PmTwoFive=55)   # Example
    ins = weather_table.insert().values(Insert_Time=datetime.utcnow(), Temperature=Current_Temp, Humidity=Current_Humi, PmTen=int(pm_10_orig), PmTwoFive=int(pm_25_orig))
    # Connect to engine and execute.
    conn = engine.connect()
    result = conn.execute(ins)

    #return Current_Temp
    return pm_25_orig


# Every 3 minutes we will see debug information, from heroku log
# @periodic_task(run_every=timedelta(minutes=3))
# @periodic_task(run_every=timedelta(seconds=3))
# def print_fib():
#     #logging.info(fib(30))
#     logging.info("This could be viewed in logging!")

This version use remote service, and it will handle the fetching/updating every 60 minutes.

Prevent Heroku from Sleeping

Register a service at https://uptimerobot.com/, it will automatically ping or get http(s) service from your web apps.

Until now, almost all of the back-end has been set up. We can fetch the data and periodly insert into the database, and our web app will continue to run(Never sleep).
Tomorrow we will try to write a beautiful front-end for our webapp.