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Python 101: Interactively learn how to program with Python 3

Working with minidom

Explore how to use Python's minidom module to parse XML files, extract elements like appointments and book titles, and handle XML data in Python programs. This lesson guides you through reading XML content, managing nodes, and processing text to help you work confidently with XML in Python.

We'll cover the following...

To start out, well need some actual XML to parse. Take a look at the following short example of XML:

XML
<?xml version="1.0" ?>
<zAppointments reminder="15">
    <appointment>
        <begin>1181251680</begin>        
        <uid>040000008200E000</uid>
        <alarmTime>1181572063</alarmTime>
        <state></state>
        <location></location>
        <duration>1800</duration>
        <subject>Bring pizza home</subject>
    </appointment>
</zAppointments>

This is fairly typical XML and actually pretty intuitive to read. There is some really nasty XML out in the wild that you may have to work with. Anyway, save the XML code above with the following name: appt.xml

Let’s spend some time getting acquainted with how to parse this file using Python’s minidom module. This is a fairly long piece of code, so prepare yourself.

Python 3.5
import xml.dom.minidom
import urllib.request
class ApptParser(object):
    def __init__(self, url, flag='url'):
        self.list = []
        self.appt_list = []        
        self.flag = flag
        self.rem_value = 0
        xml = self.getXml(url)             
        self.handleXml(xml)
    def getXml(self, url):
        try:
            print(url)
            f = urllib.request.urlopen(url)
        except:
            f = url
        doc = xml.dom.minidom.parse(f)
        node = doc.documentElement        
        if node.nodeType == xml.dom.Node.ELEMENT_NODE:
            print('Element name: %s' % node.nodeName)
            for (name, value) in node.attributes.items():
                print('    Attr -- Name: %s  Value: %s' % (name, value))
        return node
    def handleXml(self, xml):
        rem = xml.getElementsByTagName('zAppointments')        
        appointments = xml.getElementsByTagName("appointment")
        self.handleAppts(appointments)
    def getElement(self, element):
        return self.getText(element.childNodes)
    def handleAppts(self, appts):
        for appt in appts:
            self.handleAppt(appt)
            self.list = []
    def handleAppt(self, appt):
        begin     = self.getElement(appt.getElementsByTagName("begin")[0])
        duration  = self.getElement(appt.getElementsByTagName("duration")[0])
        subject   = self.getElement(appt.getElementsByTagName("subject")[0])
        location  = self.getElement(appt.getElementsByTagName("location")[0])
        uid       = self.getElement(appt.getElementsByTagName("uid")[0])
        self.list.append(begin)
        self.list.append(duration)
        self.list.append(subject)
        self.list.append(location)
        self.list.append(uid)
        if self.flag == 'file':
            try:
                state     = self.getElement(appt.getElementsByTagName("state")[0])
                self.list.append(state)
                alarm     = self.getElement(appt.getElementsByTagName("alarmTime")[0])
                self.list.append(alarm)
            except Exception as e:
                print(e)
        self.appt_list.append(self.list)        
    def getText(self, nodelist):
        rc = ""
        for node in nodelist:
            if node.nodeType == node.TEXT_NODE:
                rc = rc + node.data
        return rc
if __name__ == "__main__":
    appt = ApptParser("appt.xml")
    print(appt.appt_list)

This code is loosely based on an example from the Python documentation and I have to admit that I think my mutation of it is a bit ugly. Let’s break this code down a bit. The url parameter you see in the ApptParser ...