XML - Lesson 03: Operations on XML Elements

	Operations on XML Elements

Fundamental Operations

Introduction

So far, to create an XML element, we were directly typing in a file. When such a file had been created and saved, it was ready to be processed. Here is an example of a file named videos.xml:

<?xml version="1.0" encoding="utf-8" ?>
<videos>
  <title>The Distinguished Gentleman</title>
</videos>

In some applications, you will want the user to provide you with the necessary value(s) to create an element.

Fortunately, the XmlDocument, the XmlNode, and the XmlElement classes provide all the necessary properties and methods to perform the routine operations of an XML file, an element, or a node. The operations include locating a node, adding a new element, or deleting a node.

Before performing an operation, you will usually need to decide in what section of the file you want the action to be applied. As it happens, you have the root node, a particular node inside the document, parent of a node, the sibling of a node, etc. To get to a node, you will usually first get a reference to its XmlElement. To do this, you can declare an XmlElement variable and initialize it with that reference.

Practical Learning: Introducing operations on XML Elements

Start Microsoft Visual C# and create a Console Application named SolasPropertyRental1
To add a new form to the application, in the Solution Explorer, right-click SolasPropertyRental1 -> Add -> Windows Form...
Set the Name to Tenants and click Add
From the Toolbox, add a ListView to the form

While the new list view is still selected, in the Properties window, click the ellipsis button of the Columns field and create the columns as follows:

(Name)	Text	TextAlign	Width
colAccountNumber	Account #		65
colFullName	Full Name		120
colMaritalStatus	Marital Status		85
colPhoneNumber	Phone #	Center	85

Design the form as follows:

Control	Text	Name	Other Properties
ListView		lvwTenants	Anchor: Top, Bottom, Left, Right FullRowSelect: True GridLines: True View: Details
Button	New Tenant...	btnNewTenant	Anchor: Bottom, Right
Button	Close	btnClose	Anchor: Bottom, Right

Double-click an unoccupied area of the Tenants form

Implement the Load event as follows:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Xml;

namespace SolasPropertyRental1
{
    public partial class Tenants : Form
    {
        public Tenants()
        {
            InitializeComponent();
        }

        void ShowTenants()
        {
            string Filename = @"C:\Solas Property Rental\tenants.xml";
            XmlDocument docTenants = new XmlDocument();

            if (File.Exists(Filename))
            {
                lvwTenants.Items.Clear();

                docTenants.Load(Filename);
                XmlElement elmTenant = docTenants.DocumentElement;
                XmlNodeList lstTenants = elmTenant.ChildNodes;

                foreach (XmlNode node in lstTenants)
                {
                    ListViewItem lviTenant = new ListViewItem(node.FirstChild.InnerText); // Account Number

                    lviTenant.SubItems.Add(node.FirstChild.NextSibling.InnerText); // Full Name
                    lviTenant.SubItems.Add(node.FirstChild.NextSibling.NextSibling.InnerText); // Phone Number
                    lviTenant.SubItems.Add(node.FirstChild.NextSibling.NextSibling.NextSibling.InnerText); // Marital Status
                    lvwTenants.Items.Add(lviTenant);
                }
            }
        }

        private void Tenants_Load(object sender, EventArgs e)
        {
            ShowTenants();
        }
    }
}

To add another form to the application, in the Solution Explorer, right- click SolasPropertyRental1 -> Add -> Windows Form...
Set the Name to TenantEditor and click Add

Design the form as follows:

Control	Text	Name	Properties
Label	&Account #:
MaskedTextBox		txtAccountNumber	Mask: 00-00-00 Modifiers: public
Label	&Full Name:
TextBox		txtFullName	Modifiers: public
Label	Marital Status:
ComboBox		txtMaritalStatus	Modifiers: public Items: Single Widow Married Divorced Separated
Label	&Phone #:
MaskedTextBox		txtPhoneNumber	Mask: (999) 000-0000 Modifiers: public
Button	OK	btnOK	DialogResult: OK
Button	Cancel	btnCancel	DialogResult: Cancel
Form			AcceptButton: btnOK CancelButton: btnCancel FormBorderStyle: FixedDialog MaximizeBox: False MinimizeBox: False ShowInTaskbar: False

To add a new form to the application, in the Solution Explorer, right- click SolasPropertyRental1 -> Add -> Windows Form...
Set the Name to RentalProperties and press Enter
From the Toolbox, add a ListView to the form

While the new list view is still selected, in the Properties window, click the ellipsis button of the Columns field and create the columns as follows:

(Name)	Text	TextAlign	Width
colPropertyCode	Prop Code		65
colPropertyType	Property Type		85
colBedrooms	Bedrooms	Right	65
colBathrooms	Bathrooms	Right	65
colMonthlyRent	Monthly Rent	Right	75
colStatus	Status		65

Design the form as follows:

Control	Text	Name	Other Properties
ListView		lvwProperties	View: Details GridLines: True FullRowSelect: True Anchor: Top, Bottom, Left, Right
Button	New Property...	btnNewProperty	Anchor: Bottom, Right
Button	Close	btnClose	Anchor: Bottom, Right

Double-click an unoccupied area of the Rental Properties form and implement the Load event as follows:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Xml;

namespace SolasPropertyRental1
{
    public partial class RentalProperties : Form
    {
        public RentalProperties()
        {
            InitializeComponent();
        }

        void ShowProperties()
        {
            XmlDocument docProperties = new XmlDocument();
            string Filename = @"C:\Solas Property Rental\properties.xml";

            if (File.Exists(Filename))
            {
                lvwProperties.Items.Clear();

                docProperties.Load(Filename);
                XmlElement elmProperty = docProperties.DocumentElement;
                XmlNodeList lstProperties = elmProperty.ChildNodes;

                foreach (XmlNode node in lstProperties)
                {
                    ListViewItem lviProperty = new ListViewItem(node.FirstChild.InnerText); // Property Code

                    lviProperty.SubItems.Add(node.FirstChild.NextSibling.InnerText); // Property Type
                    lviProperty.SubItems.Add(node.FirstChild.NextSibling.NextSibling.InnerText); // Bedrooms
                    lviProperty.SubItems.Add(node.FirstChild.NextSibling.NextSibling.NextSibling.InnerText); // Bathrooms
                    lviProperty.SubItems.Add(node.FirstChild.NextSibling.NextSibling.NextSibling.NextSibling.InnerText); // Monthly Rent
                    lviProperty.SubItems.Add(node.FirstChild.NextSibling.NextSibling.NextSibling.NextSibling.NextSibling.InnerText); // Status
                    lvwProperties.Items.Add(lviProperty);
                }
            }
        }

        private void RentalProperties_Load(object sender, EventArgs e)
        {
            ShowProperties();
        }
    }
}

To add another form to the application, in the Solution Explorer, right- click SolasPropertyRental1 -> Add -> Windows Form...
Set the Name to PropertyEditor and click Add

Design the form as follows:

Control	Text	Name	Properties
Label	Property Code:
MaskedTextBox		txtPropertyCode	Mask: 000-000 Modifiers: Public
Button	OK	btnOK	DialogResult: OK
Label	Property Type:
ComboBox		cbxPropertyTypes	Modifiers: Public Items: Unknown Apartment Townhouse Single Family
Button	Cancel	btnCancel	DialogResult: Cancel
Label	Bedrooms:
TextBox	0	txtBedrooms	TextAlign: Right Modifiers: Public
Label	Bathrooms:
TextBox	0.00	txtBathrooms	TextAlign: Right Modifiers: Public
Label	Monthly Rent:
TextBox	0.00	txtMonthlyRent	TextAlign: Right Modifiers: Public
Label	Occupancy Status:
ComboBox	Unknown	cbxStatus	Modifiers: Public Items: Unknown Available Occupied Needs Repair
Form			AcceptButton: btnOK CancelButton: btnCancel FormBorderStyle: FixedDialog MaximizeBox: False MinimizeBox: False ShowInTaskbar: False

To add a new form to the application, in the Solution Explorer, right-click SolasPropertyRental1 -> Add -> Windows Form...
Set the Name to RentalAllocation and click Add
From the Toolbox, add a ListView to the form

Design the form as follows:

Solas Property Rental: Rental Allocation

Control	Text	Name	Other Properties
Label	Rent Allocation		AutoSize: False BackColor: Gray BorderStyle: FixedSingle ForeColor: White TextAlign: MiddleLeft
Label	Allocation Code:
MaskedTextBox		txtAllocationCode	Mask: 0000-9999 Modifiers: Public
Label	Date Allocated:
DateTimePicker		dtpDateAllocated	Format: Short Modifiers: Public
Label	Tenant		AutoSize: False BackColor: Gray BorderStyle: FixedSingle ForeColor: White TextAlign: MiddleLeft
Label	Property		AutoSize: False BackColor: Gray BorderStyle: FixedSingle ForeColor: White TextAlign: MiddleLeft

Label	Account #:
MaskedTextBox		txtTenantAcntNbr	Mask: 00-00-00 Modifiers: Public
Label	Property #:
MaskedTextBox		txtPropertyCode	Mask: 000-000 Modifiers: Public
Label	Tenant Name
TextBox		txtTenantName	Modifiers: Public
Label	Property Type:
TextBox		txtPropertyType	Modifiers: Public
Label	Marital Status:
TextBox		txtMaritalStatus	Modifiers: Public
Label	Monthly Rent:
TextBox		txtMonthlyRent
Label	Allocation Evaluation		AutoSize: False BackColor: Gray BorderStyle: FixedSingle ForeColor: White TextAlign: MiddleLeft
Label	Contract Length:
ComboBox		cbxContractLength	Items: Monthly 3 Months 6 Months 12 Months Modifiers: Public
Label	Rent Start Date:
DateTimePicker		dtpRentStartDate	Modifiers: Public
Button	OK	btnOK	DialogResult: OK
Button	Close	btnClose	DialogResult: Cancel
Form			AcceptButton: btnOK CancelButton: btnClose FormBorderStyle: FixedDialog MaximizeBox: False MinimizeBox: False ShowInTaskbar: False

On the form, click the Account # text box and, in the Properties window, double-click Leave

Implement the event as follows:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Xml;

namespace SolasPropertyRental1
{
    public partial class RentalAllocation : Form
    {
        public RentalAllocation()
        {
            InitializeComponent();
        }

        private void txtTenantAcntNbr_Leave(object sender, EventArgs e)
        {
            string Filename = @"C:\Solas Property Rental\tenants.xml";
            XmlDocument docTenants = new XmlDocument();

            if (File.Exists(Filename))
            {
                docTenants.Load(Filename);
                XmlElement elmTenant = docTenants.DocumentElement;
                XmlNodeList lstTenants = elmTenant.ChildNodes;
                bool TenantFound = false;

                for (int i = 0; i < lstTenants.Count; i++)
                {
                    XmlNode node = lstTenants[i];

                    if (node.FirstChild.InnerText == txtTenantAcntNber.Text)
                    {
                        TenantFound = true;
                        txtTenantName.Text = node.FirstChild.NextSibling.InnerText;
                        txtMaritalStatus.Text = node.FirstChild.NextSibling.NextSibling.InnerText;
                    }
                }

                if (TenantFound == false)
                {
                    MessageBox.Show("There is no tenant with that account number");
                    txtTenantAcntNber.Text = "";
                }
            }
            else
                MessageBox.Show("There is no list of tenants to check.");
        }
    }
}

Return to the Rent Allocation form and click the Property Code text box
In the Events section of the Properties window, double-click Leave

Implement the event as follows:

private void txtPropertyCode_Leave(object sender, EventArgs e)
{
    string Filename = @"C:\Solas Property Rental\properties.xml";
    XmlDocument docProperties = new XmlDocument();

    if (File.Exists(Filename))
    {
        docProperties.Load(Filename);
        XmlElement elmProperty = docProperties.DocumentElement;
        XmlNodeList lstProperties = elmProperty.ChildNodes;
        bool PropertyFound = false;

        for (int i = 0; i < lstProperties.Count; i++)
        {
            XmlNode node = lstProperties[i];

            if (node.FirstChild.InnerText == txtPropertyCode.Text)
            {
                PropertyFound = true;
                txtPropertyType.Text = node.FirstChild.NextSibling.InnerText;
                txtMonthlyRent.Text = node.FirstChild.NextSibling.NextSibling.NextSibling.NextSibling.InnerText;
            }
        }

        if (PropertyFound == false)
        {
            MessageBox.Show("There is no Property with that code");
            txtPropertyType.Text = "";
        }
    }
    else
        MessageBox.Show("There is no list of properties to check.");
}

To add a new form to the application, in the Solution Explorer, right- click SolasPropertyRental1 -> Add -> Windows Form...
Set the Name to RentalAllocations and press Enter
From the Toolbox, add a ListView to the form

While the new list view is still selected, in the Properties window, click the ellipsis button of the Columns field and create the columns as follows:

(Name)	Text	TextAlign	Width
colAllocationCode	Alloc Code		65
colDateAllocated	Date Allocated	Center	85
colTenantAccount	Tenant #	Center	65
colTenantName	Tenant Name		100
colPropertyCode	Prop Code	Center	65
colPropertyType	Prop Type		75
colContractLength	Contract Length		88
colRentStartDate	Rent Start Date	Center	88
colMonthlyRent	Monthly Rent	Right	76

Design the form as follows:

  
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
    
    
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
                
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                            
                Control
                Text
                Name
                Other Properties
              
                               
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                                 
                ListView
                lvwAllocations
                View: Details  GridLines: True
FullRowSelect: True
                  Anchor: Top, Bottom, Left, Right