Desktop Notifier in Python

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This article demonstrates how to create a simple Desktop Notifier application using Python.

A desktop notifier is a simple application which produces a notification message in form of a pop-up message on desktop.

Notification content

In the example we use in this article, the content that will appear as notification on desktop is the top news headlines of the day.

So, in order to fetch the top headlines, we will be using this Python script to scrape news headlines:

import requests 
import xml.etree.ElementTree as ET 

# url of news rss feed 
RSS_FEED_URL = "http://www.hindustantimes.com/rss/topnews/rssfeed.xml"  

def loadRSS(): 
    ''' 
    utility function to load RSS feed 
    '''
    # create HTTP request response object 
    resp = requests.get(RSS_FEED_URL) 

    # return response content 
    return resp.content 

def parseXML(rss): 
    ''' 
    utility function to parse XML format rss feed 
    '''
    # create element tree root object 
    root = ET.fromstring(rss) 

    # create empty list for news items 
    newsitems = [] 

    # iterate news items 
    for item in root.findall('./channel/item'): 
        news = {} 

        # iterate child elements of item 
        for child in item: 

            # special checking for namespace object content:media 
            if child.tag == '{http://search.yahoo.com/mrss/}content': 
                news['media'] = child.attrib['url'] 
            else: 
                news[child.tag] = child.text.encode('utf8') 
        newsitems.append(news) 

    # return news items list 
    return newsitems 

def topStories(): 
    ''' 
    main function to generate and return news items 
    '''
    # load rss feed 
    rss = loadRSS() 

    # parse XML 
    newsitems = parseXML(rss) 
    return newsitems

It is a simple Python script which parses the news headlines available in XML format.

Note: To understand how XML parsing works, please refer this article: XML parsing in Python

A sample news item generated by above Python script looks like this:

{'description': 'Months after it was first reported, the feud between Dwayne Johnson and 
                 Vin Diesel continues to rage on, with a new report saying that the two are 
                 being kept apart during the promotions of The Fate of the Furious.',
 'link': 'http://www.hindustantimes.com/hollywood/vin-diesel-dwayne-johnson-feud-rages-
on-they-re-being-kept-apart-for-fast-8-tour/story-Bwl2Nx8gja9T15aMvcrcvL.html',
 'media': 'http://www.hindustantimes.com/rf/image_size_630x354/HT/p2/2017/04/01/Pictures
/_fbcbdc10-1697-11e7-9d7a-cd3db232b835.jpg',
 'pubDate': b'Sat, 01 Apr 2017 05:22:51 GMT ',
 'title': "Vin Diesel, Dwayne Johnson feud rages on; they're being deliberately kept apart"}

Save this Python script as topnews.py (as we import it by this name in our desktop notifier app).

Installations

Now, in order to create a desktop notifier, you need to install a third party Python module, notify2.

You can install notify2 using a simple pip command:

pip install notify2

Desktop notifier app

Now, we write the Python script for our desktop notifier.

Consider the code below:

import time 
import notify2 
from topnews import topStories 

# path to notification window icon 
ICON_PATH = "put full path to icon image here"

# fetch news items 
newsitems = topStories() 

# initialise the d-bus connection 
notify2.init("News Notifier") 

# create Notification object 
n = notify2.Notification(None, icon = ICON_PATH) 

# set urgency level 
n.set_urgency(notify2.URGENCY_NORMAL) 

# set timeout for a notification 
n.set_timeout(10000) 

for newsitem in newsitems: 

    # update notification data for Notification object 
    n.update(newsitem['title'], newsitem['description']) 

    # show notification on screen 
    n.show() 

    # short delay between notifications 
    time.sleep(15)

Let us try to analyze above code step by step:

• Before we can send any notifications, we need to initialize a D-Bus connection. D-Bus is a message bus system, a simple way for applications to talk to one another. So, D-Bus connection for notify2 in current Python script is initialized using:

  notify2.init("News Notifier")

  Here, the only argument we passed is the app name. You can set any arbitrary app name.

• Now, we create a notification object,

n

using:

n = notify2.Notification(None, icon = ICON_PATH)

The general syntax for above method is:

notify2.Notification(summary, message='', icon='')

Here,

• summary: The title text
• message: The body text

• icon: Path to an icon image

  Currently, we have set summary as None and passed the ICON_PATH as icon argument.

  Note: You need to pass complete path of the icon image.

• You can optionally set the urgency level of notifications using

set_urgency

method:

n.set_urgency(notify2.URGENCY_NORMAL)

The available constants are:

• notify2.URGENCY_LOW
• notify2.URGENCY_NORMAL
• notify2.URGENCY_CRITICAL

• Another optional utility is

set_timeout

method using which, you can explicitly set the display duration in milliseconds as shown below:

n.set_timeout(10000)

• Now, as we iterate through each news item one by one, we need to update notification object with a new

summary

and

message

using

update

method:

n.update(newsitem['title'], newsitem['description'])

• In order to display a notification, simply call

show()

method of Notification object like this:

n.show()

A sample screen shot of desktop when you run above Python script:

Github repository for this desktop notifier application: Desktop-Notifier-Example

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原文链接：codingdict.net

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