WPF Data Binding Tutorial 2

  We already saw basics of WPF Binding in Chapter 1 (refer WPF Data Binding Tutorial 1)

    Now we would see the next topic i.e. Using C#[INotifyPropertyChanged].In this chapter, I would cover  usage of INotifyPropertyChanged and how to bind data in WPF. What is the purpose, we need to use INotifyPropertyChanged?  Event is fired  whenever a property Changed. In the following example we see how the UI can know that this event is fired.

           We achieve same resulst in implemented the INotifyPropertyChanged interface in the Student class to generate an event every time the value in the  object's property changes.I have highlighted some codes in below example that"s need to be added to implement INotifyPropertyChanged.

 create class the class name is Student

Student.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
using System.Windows;
using System.ComponentModel;
using System.Data;

namespace WPF_Tutorial
{
 public  class Students:INotifyPropertyChanged
   {
       #region Studentdetails
       private int _Rollno;
       public int Rollno
       {
           get{ return _Rollno; }
           set{ _Rollno = value;
            OnPropertyChanged("Rollno");
                  }
       }
       private string _FirstName;
       public string FirstName
       {
           get{ return _FirstName; }
           set{ _FirstName = value;
           OnPropertyChanged("FirsName");
           }
       }
       private string _Lastname;
       public string Lastname
       {
          get{ return _Lastname; }
          set{ _Lastname = value;
           OnPropertyChanged("Lastname");
           }
       }
       private string _Colleagename;
       public string Colleagename
       {
           get{ return _Colleagename; }
           set{ _Colleagename = value;
          OnPropertyChanged("Colleagename");
           }
       }
       private int _Marksobtaine;
       public int Marksobtaine
       {
           get{ return _Marksobtaine; }
           set{ _Marksobtaine = value;
           OnPropertyChanged("Marksobtaine");
           }
       }
       private string _Exam;
       public string Exam
       {
          get{ return _Exam; }
           set{ _Exam = value;
           OnPropertyChanged("Exam");
          }
       }
       #endregion
       public Students()
        {
        }

        public SqlCommand objcmd;
       #region insertDetail
       public void Insetrt()
       {
               SqlConnectionobjCon = new SqlConnection("");//connection name
           try
           {
              objCon.Open();
                  objcmd = new SqlCommand("insert into StudentInformation
                     values(@Rollno,@Fname,@Lname,@Mark,@clgname,@Exam) ", objCon);
               objcmd.Parameters.AddWithValue("@Rollno", Rollno);
               objcmd.Parameters.AddWithValue("@Fname", FirstName);
               objcmd.Parameters.AddWithValue("@Lname", Lastname);
               objcmd.Parameters.AddWithValue("@clgname", Colleagename);
               objcmd.Parameters.AddWithValue("@Mark", Marksobtaine);
               objcmd.Parameters.AddWithValue("@Exam", Exam);
            //On property   changed
                OnPropertyChanged("Rollno");
               OnPropertyChanged("FirstName");
               OnPropertyChanged("Lastname");
               OnPropertyChanged("Colleagename");
               OnPropertyChanged("Marksobtaine");
               OnPropertyChanged("Exam");
               objcmd.ExecuteNonQuery();
           }
           catch (Exception ex)
           {
               MessageBox.Show("" + ex);
           }
           finally
           {
               objcmd.Dispose();
               if(objCon.State == ConnectionState.Open)
               {
                   objCon.Close();
                   objCon.Dispose();
               }
           }
           }
       #endregion
       #region LoadDetails
    public void Load()
       {
           SqlConnection objCon = new SqlConnection(""); //connection name
                   objCon.Open();
                   objcmd = new SqlCommand("Select * from StudentInformation where
Rollno=@Rollno", objCon);//select command
                   objcmd.Parameters.Add(new SqlParameter("@Rollno", _Rollno));
                   try
                   {
                       SqlDataReader objRDR = objcmd.ExecuteReader();
                       if(objRDR.Read())
                       {
                           _FirstName = objRDR["Fname"].ToString();
                           _Lastname = objRDR["Lname"].ToString();
                           _Colleagename =objRDR["Clgname"].ToString();
                           _Marksobtaine = Convert.ToInt32(objRDR["Mark"]);
                           _Exam = objRDR["Exam"].ToString();
                           //property changed
                       
                             OnPropertyChanged("Rollno");
                           OnPropertyChanged("FirstName");
                           OnPropertyChanged("Lastname");
                           OnPropertyChanged("Colleagename");
                           OnPropertyChanged("Marksobtaine");
                           OnPropertyChanged("Exam");
                       }
                       else
                       {
                         MessageBox.Show("RecordNot Found");
                       }
                   }
                   catch(Exception ex)
                   {
                       MessageBox.Show("" + ex);
                   }
                   finally
                   {
                       objcmd.Dispose();
                       if(objCon.State == ConnectionState.Open)
                       {
                           objCon.Close();
                          objCon.Dispose();
                       }

                   }
           }
       #endregion
       #region UpdateDetails
    public void update()
    {

           SqlConnection objCon = new SqlConnection(""); //connection name
            objCon.Open();
            objcmd = new SqlCommand("update
                   StudentInformation set
                   Fname=@Fname,Lname=@Lname,Mark=@Mark,Clgname=@Clgname,Exam=@Exam where
                     Rollno=@Rollno ", objCon);
            objcmd.Parameters.Add(new SqlParameter("@Rollno", _Rollno));
            try
            {
                objcmd.Parameters.AddWithValue("@Fname", FirstName);
                objcmd.Parameters.AddWithValue("@Lname", Lastname);
                objcmd.Parameters.AddWithValue("@Clgname", Colleagename);
                objcmd.Parameters.AddWithValue("@Mark", Marksobtaine);
                objcmd.Parameters.AddWithValue("@Exam", Exam);
                //propertychanged              
                OnPropertyChanged("Rollno");
                OnPropertyChanged("FirstName");
                OnPropertyChanged("Lastname");
                OnPropertyChanged("Colleagename");
                OnPropertyChanged("Marksobtaine");
                OnPropertyChanged("Exam");
                objcmd.ExecuteNonQuery();
            }

            catch (Exception ex)
            {
                MessageBox.Show("" + ex);
            }
            finally
           {
                objcmd.Dispose();
                if(objCon.State == ConnectionState.Open)
                {
                    objCon.Close();
                    objCon.Dispose();
                }
            }
        }
    #region INotifyPropertyChanged Members
 
   public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string PropertyName)
    {
        if (this.PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(PropertyName));
        }

    }
    #endregion
   }
       #endregio
   }

 

The INotifyPropertyChanged interface implementation allows the class to raise the PropertyChanged event everytime a property value changes. The above class can now be instanitated in the code-behind file of another XAML file (WithoutXAML.xaml) which is similar to that of code listing in below(UI Side).

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.ComponentModel;
namespace WPF_Tutorial
{
    public partial class Dataentry : Window
    {
        Students objStudent = new Students();
        public Dataentry()
        {
            InitializeComponent();
        }
        //insert record

        private void btnAdd_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                objStudent.Insetrt();
                MessageBox.Show("Record inserted", "Insert");
                //clearField

                txtRollNo.Text = "";
                txtFirstName.Text = "";
                txtLastName.Text = "";
                txtClgname.Text = "";
                txtexamresult.Text = "";
                txtMarks.Text = "";
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
        //load record
        private void btnLoad_Click(object sender, RoutedEventArgs e)
        {
            if (txtRollNo.Text != null)
            {
                try
                {
                    objStudent.Rollno = Convert.ToInt32(txtRollNo.Text);
                    objStudent.Load();
                }
                catch(Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
            }
            else
            {
                MessageBox.Show("enter correct code");
            }
        }

        //update record

        private void btnUpdate_Click(object sender, RoutedEventArgs e)
        {
            if (txtRollNo.Text != null)
            {
                try
                {
                    objStudent.Rollno = Convert.ToInt32(txtRollNo.Text);
                     objStudent.update();
                    MessageBox.Show("Update Record", "Update");
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
            }
        }
        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            objStudent.PropertyChanged += objStudent_PropertyChanged;
        }

        // Property Changed Event Handler [Pathetic Code!]
       
 private void objStudent_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            switch (e.PropertyName)
            {
                case "Rollno":
                    txtRollNo.Text = Convert.ToString(objStudent.Rollno);
                    break;
                case "FirstName":
                    txtFirstName.Text =objStudent.FirstName;
                    break;
                case "Lastname":
                    txtLastName.Text = objStudent.Lastname;
                    break;
                case "Colleagename":
                    txtClgname.Text = objStudent.Colleagename;
                    break;
                case "Marksobtaine":
                    txtMarks.Text = Convert.ToString(objStudent.Marksobtaine);
                    break;
                case "Exam":
                    txtexamresult.Text = objStudent.Exam;
                    break;
            }
        }


        private void txtRollNo_TextChanged(object sender, TextChangedEventArgs e)
        {
            objStudent.Rollno =Convert.ToInt32(txtRollNo.Text);
        }
        private void txtFirstName_TextChanged(object sender, TextChangedEventArgs e)
        {
            objStudent.FirstName = txtFirstName.Text;
        }
        private void txtLastName_TextChanged(object sender, TextChangedEventArgs e)
        {
            objStudent.Lastname = txtLastName.Text;
        }
        private void txtClgname_TextChanged(object sender, TextChangedEventArgs e)
        {
            objStudent.Colleagename =  txtClgname.Text;
        }
        private void txtMarks_TextChanged(object sender, TextChangedEventArgs e)
        {
            objStudent.Marksobtaine = Convert.ToInt32(txtMarks.Text);
        }
        private void txtexamresult_TextChanged(object sender, TextChangedEventArgs e)
        {
            objStudent.Exam = txtexamresult.Text;
        }
    }
}