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Posts Tagged ‘xml’

Check Gmail for new messages

September 8, 2012 Leave a comment

Problem
I want to check my new Gmail messages periodically. When I get a message from a specific sender (with a specific Subject), I want to trigger some action. How to do that?

Solution
Fortunately, there is an atom feed of unread Gmail messages at https://mail.google.com/mail/feed/atom. All you have to do it is visit this page, send your login credentials, fetch the feed and process it.

import urllib2

FEED_URL = 'https://mail.google.com/mail/feed/atom'

def get_unread_msgs(user, passwd):
    auth_handler = urllib2.HTTPBasicAuthHandler()
    auth_handler.add_password(
        realm='New mail feed',
        uri='https://mail.google.com',
        user='{user}@gmail.com'.format(user=user),
        passwd=passwd
    )
    opener = urllib2.build_opener(auth_handler)
    urllib2.install_opener(opener)
    feed = urllib2.urlopen(FEED_URL)
    return feed.read()

##########

if __name__ == "__main__":
    import getpass

    user = raw_input('Username: ')
    passwd = getpass.getpass('Password: ')
    print get_unread_msgs(user, passwd)

For reading XML I use the untangle module:

import untangle    # sudo pip install untangle

xml = get_unread_msgs(USER, PASSWORD)
o = untangle.parse(xml)
try:
    for e in o.feed.entry:
        title = e.title.cdata
        print title
except IndexError:
    pass    # no new mail

Links

Categories: python Tags: , , , ,

Serializations: data <-> XML, data <-> JSON, XML <->JSON

January 20, 2012 Leave a comment

Problems

  1. Python data to XML and back
  2. Python data to JSON and back
  3. XML to JSON and back

Solution

import json
import xmlrpclib
from xml2json import Xml2Json

def data_to_xmlrpc(data):
    # http://www.reddit.com/r/Python/comments/ole01/dictionary_to_xml_in_20_lines/
    """Return value: XML RPC string."""
    return xmlrpclib.dumps((data,)) # arg. is tuple

def xmlrpc_to_data(xml):
    # http://www.reddit.com/r/Python/comments/ole01/dictionary_to_xml_in_20_lines/
    """Return value: python data."""
    return xmlrpclib.loads(xml)[0][0]

def data_to_json(data):
    """Return value: JSON string."""
    data_string = json.dumps(data)
    return data_string

def json_to_data(data_string):
    """Return value: python data."""
    data = json.loads(data_string)
    return data

def xml_to_json(xml):
    """Return value: JSON string."""
    res = Xml2Json(xml).result
    return json.dumps(res)

def json_to_xmlrpc(data_string):
    """Return value: XML RPC string."""
    data = json.loads(data_string)
    return data_to_xmlrpc(data)

def xmlrpc_to_json(xmlrpc):
    """Return value: JSON string."""
    data = xmlrpc_to_data(xmlrpc)
    return data_to_json(data)

The full source code (serialize.py) together with the imported xml2json.py are available here. This work is part of my jabbapylib library.

Examples
Unit tests are here, they show you how to use these functions. Examples with comments are here.

Categories: python Tags: , , ,

Read XML painlessly

October 30, 2011 3 comments

Problem
I had an XML file (an RSS feed) from which I wanted to extract some data. I tried some XML libraries but I didn’t like any of them. Is there a simple, brain-friendly way for this? After all, it’s Python, so everything should be simple.

Solution
Yes, there is a simple library for reading XML called “untangle“, developed by Chris Stefanescu. It’s in PyPI, so installation is very easy:

sudo pip install untangle

For some examples, visit the project page.

Use Case
Let’s see a simple, real-world example. From the RSS feed of Planet Python, let’s extract the post titles and their URLs.

#!/usr/bin/env python

import untangle

#XML = 'examples/planet_python.xml'     # can read a file too
XML = 'http://planet.python.org/rss20.xml'

o = untangle.parse(XML)
for item in o.rss.channel.item:
    title = item.title.cdata
    link = item.link.cdata
    if link:
        print title
        print '   ', link

It couldn’t be any simpler :)

Limitations
According to Chris, untangle doesn’t support documents with namespaces (yet).

Related posts

Alternatives (update 20111031)
Here are some alternatives (thanks reddit).

lxml and amara are heavyweight solutions and are built upon C libraries so you may not be able to use them everywhere. untangle is a lightweight parser that can be a perfect choice to read a small and simple XML file.

Categories: python Tags: , , , , ,

Write XML to file

April 4, 2011 2 comments

Problem

I wanted to create an XML file. The file was simple but I wanted to avoid producing it with “print” commands. Which API should be used for this purpose? The produced XML should be human readable, i.e. pretty printed (indented).

Solution

This post is based on the thread Best XML writing tool for Python.

(1) elementtree.SimpleXMLWriter (no indenting)

The SimpleXMLWriter module contains a simple helper class for applications that need to generate well-formed XML data. The interface is very simple:

#!/usr/bin/env python

from elementtree.SimpleXMLWriter import XMLWriter
import sys

w = XMLWriter(sys.stdout)
html = w.start("html")

w.start("head")
w.element("title", "my document")
w.element("meta", name="generator", value="my application 1.0")
w.end()

w.start("body")
w.element("h1", "this is a heading")
w.element("p", "this is a paragraph")

w.start("p")
w.data("this is ")
w.element("b", "bold")
w.data(" and ")
w.element("i", "italic")
w.data(".")
w.end("p")

w.close(html)

However, the output is not indented and as I saw, this feature is missing :( Here is the output of the code above:

<html><head><title>my document</title><meta name="generator" value="my application 1.0" /></head><body><h1>this is a heading</h1><p>this is a paragraph</p><p>this is <b>bold</b> and <i>italic</i>.</p></body></html>

If we prettify it, it will look like this:

<?xml version="1.0"?>
<html>
  <head>
    <title>my document</title>
    <meta name="generator" value="my application 1.0"/>
  </head>
  <body>
    <h1>this is a heading</h1>
    <p>this is a paragraph</p>
    <p>this is <b>bold</b> and <i>italic</i>.</p>
  </body>
</html>

You can install elementtree from PyPI.

(2) lxml.etree (can do indenting)

This is what I chose for my project. This API is also very easy to use and it can do indenting. Documentation is here.

Example:

#!/usr/bin/env python

from lxml import etree as ET

root = ET.Element('background')
starttime = ET.SubElement(root, 'starttime')
hour = ET.SubElement(starttime, 'hour')
hour.text = '00'
minute = ET.SubElement(starttime, 'minute')
minute.text = '00'
second = ET.SubElement(starttime, 'second')
second.text = '01'

print ET.tostring(root, pretty_print=True, xml_declaration=True)
# write to file:
# tree = ET.ElementTree(root)
# tree.write('output.xml', pretty_print=True, xml_declaration=True)

Output:

<?xml version='1.0' encoding='ASCII'?>
<background>
  <starttime>
    <hour>00</hour>
    <minute>00</minute>
    <second>01</second>
  </starttime>
</background>

Installation:
On PyPI, you can find lxml here. However, you will have to install some additional packages too:

sudo apt-get install libxml2-dev
sudo apt-get install libxslt-dev
# until Ubuntu 10.10:
sudo apt-get install python2.6-dev
# from Ubuntu 11.04:
sudo apt-get install python2.7-dev

Then, you can install the library with “sudo pip install lxml“.

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