Python CRUD Operations With XML File

Using Python XML.etree.ElementTree module to do CRUD operations with an XML file.

Introduction

 

In this blog, we will learn how to perform basic CRUD application using Python and an XML file. We will also learn how to create a Python module and use it. 

 

Prerequisite 

 

VS Code or any other IDE for development.

 

Step 1

 

Create an XML file. Here, I have created a contact.xml with the following structure.

<data>
    <contact id="1">
        <name>john doe</name>
        <address>unknown</address>
        <phone>007</phone>
    </contact>
    <contact id="2">
        <name>Test2</name>
        <address>Test Address2</address>
        <phone>1002</phone>
    </contact>
</data>

Step 2

 

Creating Python module for CRUD operations.We will be using Python xml.etree.ElementTree module for creating and reading  the XML data. I have created two files - myxml.py which is the application file and mymodules.py which has all functions of CRUD. We will import mymodules.py in our application file. I have included comments in the code for better understanding. The code is as below,

 

mymodules.py

myroot=''
def setXml(root,tree):
    global myroot
    global mytree
    myroot=root
    mytree=tree
# Function to list all xml elements
def readContact():
    global myroot
    for contact in myroot.findall('contact'):
        contactId=contact.attrib['id']
        name=contact.find('name').text
        address=contact.find('address').text
        phone=contact.find('phone').text
        print("  Name =",name,"\n"," Address =",address,"\n",
        " Phone =",phone,"\n"," Id =",contactId)
        print("----------------------------")
    input("Press any key to continue...")
# Function to return next element id
def getId():
    global myroot
    temp = 0
    for contact in myroot.findall('contact'):
        id= int(contact.attrib['id'])
        if id>temp:
            temp=id
    return temp+1
# Function to create a new element
def newContact(ET):
    global myroot
    global mytree
    print("Create a record")
    name=input("Name:")
    address=input("Address:")
    phone=input("Phone:")
    nextId=getId()
    newrecord = ET.SubElement(myroot, "contact",id=str(nextId))
    ET.SubElement(newrecord, "name", name="name").text = name
    ET.SubElement(newrecord, "address", name="address").text = address
    ET.SubElement(newrecord, "phone", name="phone").text = phone
    mytree.write("contact.xml")
    print("Contact created...")
# Function to delete a element
def deleteContact():
    global myroot
    global mytree
    deleteRecord=int(input("Enter the id of the contact you want to delete: "))
    #loop through all id's
    for contact in myroot.findall('contact'):
        delid= int(contact.attrib['id'])
        if delid == deleteRecord:
            myroot.remove(contact)
            mytree.write("contact.xml")
            print("Contact deleted...")
# Function to update a element
def updateContact():
    global myroot
    global mytree
    updateRecord=int(input("Enter the id of contact you want to update: "))
    for contact in myroot.findall('contact'):
        upid= int(contact.attrib['id'])
        if upid == updateRecord:
            #first we will select all current values
            name = contact.find('name').text
            address = contact.find('address').text
            phone = contact.find('phone').text
           #update..the or input means if input is empty keep old value
            name = input("Please enter name:") or name
            contact.find('name').text= name
            address = input("Please enter address:") or address
            contact.find('address').text= address
            phone = input("Please enter phone:") or phone
            contact.find('phone').text= phone
            mytree.write("contact.xml")
            print("Contact updated...")

myxml.py

import xml.etree.ElementTree as ET
import sys
#importing module we created as myfun
import mymodules as myfun
try:
    mytree = ET.parse('contact.xml')
    myroot = mytree.getroot()
    choice=int(input('What you want to do..?\n 1.List\n 2.Insert \n 3.Update \n 4.Delete \n'))
    myfun.setXml(myroot,mytree)
    #using python conditional statement..calls function according to choice
    myfun.newContact(ET) if choice ==2 else ""
    myfun.updateContact() if choice ==3 else ""
    myfun.deleteContact() if choice ==4 else ""
    myfun.readContact() if choice ==1 else ""
except OSError as err:
    print("OS error: {0}".format(err))
except:
    print("Unexpected error:", sys.exc_info()[0])
    raise

Step 3

 

Run the myxml.py in the terminal. The screenshot of output as in vscode is as below.