XML parsing with class will not find the values

Question

I will split a large XML to small branches and than parse only this parts. I search modified timestamp "mod_time" tag which is avaliable in "contacts" tag, but my object function call, doesn't find the value. In some contacts is also some tags missing completly.

I tried iterfind('tag_name'), iter(), findall('tag_name'), but my program shows no result and I can't figure out for hours, where my failure is.

Here is my XML reduced to two elements:

<?xml version="1.0" encoding = "utf-8"?>
<phonebooks>
  <phonebook name="Telefonbuch">
   <contact>
      <category>0</category>
      <person>
        <realName>Dummy, Name, Street</realName>
      </person>
      <telephony nid="1">
        <number type="work" prio="1" id="0">012345678</number>
      </telephony>
      <services />
      <setup />
      <features doorphone="0" />
      <mod_time>1587477163</mod_time>
      <uniqueid>358</uniqueid>
    </contact>
    <contact>
      <category>0</category>
      <person>
        <realName>Foto Name</realName>
      </person>
      <telephony nid="1">
        <number type="home" prio="1" id="0">067856743</number>
      </telephony>
      <services />
      <setup />
      <features doorphone="0" />
      <mod_time>1547749691</mod_time>
      <uniqueid>68</uniqueid>
    </contact>
</phonebook>
</phonebooks>

and her what I have done so fare:

import timeit
import xml.etree.ElementTree as ET

class Phonebook:
    def __init__(self, xml_file, tag_node):
        """Split tree in contact branches """
        self.xml_file = xml_file
        self.tag_node = tag_node
        # For furter parsing
        contacts = []
        i = 0
        events =('start','end','start-ns','end-ns')
        for event, elem in ET.iterparse(self.xml_file, events=events):
            if event == 'end' and elem.tag == self.tag_node[0]:
                #print(elem.tag)
                contacts.append(elem)
                par = Contact(elem, i)
                par.parse_node(elem, i)
                i += 1
            elem.clear()
        print("Amount of contacts:", len(contacts))


class Contact:
    def __init__(self, branch, i):
        self.tree = branch
        #print(i, self.tree)
       
    def parse_node(self, branch, i):
        for node in branch.iterfind('.//mod_time'):
           print(node.text)               
         
def main():
    elem = Phonebook('new _dummy1.xml',['contact'])

    
if __name__ == '__main__':
    """ Input XML file definition """
    starttime=timeit.default_timer()
    main()
    print('Finished')
    print("Runtime:", timeit.default_timer()-starttime)

Output: Amount of contacts: 2 Finished Runtime: 0.0006361000050674193

Expected output:

1587477163 1547749691

Answer 1

Code

import timeit
import xml.etree.ElementTree as ET

class Phonebook:
    def __init__(self, xml_file, selector):
        self.xml_file = xml_file
        self.selector = selector
        root = ET.parse(xml_file)
        contacts = root.findall(selector)  
        print("Amount of contacts:", len(contacts))
        for mod_time in contacts:
            print(mod_time.text)

def main():
    Phonebook('./_dummy1.xml','.//contact/mod_time')

if __name__ == '__main__':
    starttime=timeit.default_timer()
    main()
    print('Finished')
    print("Runtime:", timeit.default_timer()-starttime)

Output

$ python test.py
Amount of contacts: 2
1587477163
1547749691
Finished
Runtime: 0.0006627999973716214

Answer 2

I solved now my issue with the handshake of the object data. I create now an instance of Contact which inherit the values from the parent class Phonbook, instead of call Contact from Phonbook Object. Very helpful was the python documentation about the

super()

function, which refers to this great page. I post my solution, because it's maybe interessting for others who run in similar issues. Thanks to all who tried to help!

My changed code:

import psutil
import timeit

import xml.etree.ElementTree as ET

class Phonebook:
    def __init__(self, file_path):
        """Split tree in contact branches """
        self.file_path = file_path
    
    def contacts_list(self, file_path):    
        contacts = []
        events =('start','end','start-ns','end-ns')
        for event, elem in ET.iterparse(self.file_path, events=events):
            if event == 'end' and elem.tag == 'contact':
                contact = elem
                contacts.append(contact)
        elem.clear()
        return contacts
        #print("Superclass:",contacts)
        
class Contact(Phonebook):
    def __init__(self, file_path):
        super().__init__(file_path)
               
    def search_node(self, contact, searched_tag):
        contact_template =['category','person', 'telephony', 'services', 'setup', 'features', 'mod_time', 'uniqueid' ]
        node_tag_list = []
        list_difference = []
        search_list = []
        for node in contact:
            if node.tag not in node_tag_list:
                node_tag_list.append(node.tag)
        for element in contact_template:
            if element not in node_tag_list:
                list_difference.append(element)
        
        for node in contact:
            if node.tag == searched_tag and node.tag not in list_difference:
                search_list.append(node.text)
                #print(node.text)
            else:
                if len(list_difference) != 0 and searched_tag in list_difference:
                    message = self.missed_tag(list_difference)
                    #print(message)
                    if message not in search_list:
                        search_list.append(message)                
        return  search_list
                        
    def missed_tag(self, list_difference):
        for m in list_difference:
            message = f'{m} - not assigned'
            return message
                    
         
def main():
    con = Contact('dummy.xml')
    contacts = con.contacts_list(('dummy.xml'))
    
    mod_time_list =[]
    for contact in contacts:
        mod_time = con.search_node(contact, 'mod_time')
        mod_time_list.append(mod_time)
    print(len(mod_time_list))
    print(mod_time_list)
    
if __name__ == '__main__':
    """ Input XML file definition """
    starttime=timeit.default_timer()
    main()
    print('Finished')
    # Getting % usage of virtual_memory ( 3rd field)
    print('RAM memory % used:', psutil.virtual_memory()[2])
    # Getting usage of virtual_memory in GB ( 4th field)
    print('RAM Used (GB):', psutil.virtual_memory()[3]/1000000000)
    print("Runtime:", timeit.default_timer()-starttime)