INotifyPropertyChanged Bug ?

[John Greenwood]

Hi,

I'm not sure if i'm misunderstanding how INotifyPropertyChanged should
work but it's not working as I expected.

I have a sample program with a very simple 'Customer' class with three
properties code, name & address. All these are bound to a form via a
BindingSource and fire the PropertyChanged event when the property is
modified.

I change one of these properties in code and find that all of the
properties are fetched and rebound to the form. Is this correct ?
What's the point of specifying a property name in the
PropertyChangedEventArgs if all the controls are rebound anyway.

Any help would be much appreciated

John

If it's any help my code is below

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

namespace NotifyChange
{
public partial class Form1 : Form
{
private Customer _customer;

public Form1()
{
InitializeComponent();
_customer = new Customer();
_customer.Code = "G001";
_customer.Name = "Greenwood Enterpises Ltd";
_customer.Address = "128 Smithey Road";
customerBindingSource.DataSource = _customer;
}

private void button1_Click(object sender, EventArgs e)
{
Console.WriteLine("<-- Change Code --");

_customer.Code = "F001";

Console.WriteLine("-- Change Code -->");
}

private void button2_Click(object sender, EventArgs e)
{
Console.WriteLine("<-- Change Name --");

_customer.Name = "Fletcher Business Services Ltd";

Console.WriteLine("-- Change Name -->");
}

}

public class Customer : INotifyPropertyChanged
{

private string _code = "";
private string _name = "";
private string _address = "";

public string Code
{
get
{
Console.WriteLine("Got 'Code' at {0}", DateTime.Now);
return _code;
}
set
{
if (_code != value)
{
_code = value;

NotifyPropertyChanged(" Code");
}
}
}

public string Name
{
get
{
Console.WriteLine("Got 'Name' at {0}", DateTime.Now);
return _name;
}
set
{
if (_name != value)
{
_name = value;

NotifyPropertyChanged("Name");
}
}
}

public string Address
{
get
{
Console.WriteLine("Got 'Address' at {0}",
DateTime.Now);
return _address;
}
set
{
_address = value;
}
}

private void NotifyPropertyChanged(string Name)
{

if (PropertyChanged != null)
{
PropertyChanged(this, new
PropertyChangedEventArgs(Name));
}
}
#region INotifyPropertyChanged Members

public event PropertyChangedEventHandler PropertyChanged;

#endregion
}

[AMDRIT]

I would think that propertychanged means that it already happened, while
propertychanging gives you the opportunity to stop it.

take a look at how formclosing and formclosed behave.

"John Greenwood" <jo************@bhpit.co.ukwrote in message
news:2d********************************@4ax.com...

Hi,

I'm not sure if i'm misunderstanding how INotifyPropertyChanged should
work but it's not working as I expected.

I have a sample program with a very simple 'Customer' class with three
properties code, name & address. All these are bound to a form via a
BindingSource and fire the PropertyChanged event when the property is
modified.

I change one of these properties in code and find that all of the
properties are fetched and rebound to the form. Is this correct ?
What's the point of specifying a property name in the
PropertyChangedEventArgs if all the controls are rebound anyway.

Any help would be much appreciated

John

If it's any help my code is below

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

namespace NotifyChange
{
public partial class Form1 : Form
{
private Customer _customer;

public Form1()
{
InitializeComponent();
_customer = new Customer();
_customer.Code = "G001";
_customer.Name = "Greenwood Enterpises Ltd";
_customer.Address = "128 Smithey Road";
customerBindingSource.DataSource = _customer;
}

private void button1_Click(object sender, EventArgs e)
{
Console.WriteLine("<-- Change Code --");

_customer.Code = "F001";

Console.WriteLine("-- Change Code -->");
}

private void button2_Click(object sender, EventArgs e)
{
Console.WriteLine("<-- Change Name --");

_customer.Name = "Fletcher Business Services Ltd";

Console.WriteLine("-- Change Name -->");
}

}

public class Customer : INotifyPropertyChanged
{

private string _code = "";
private string _name = "";
private string _address = "";

public string Code
{
get
{
Console.WriteLine("Got 'Code' at {0}", DateTime.Now);
return _code;
}
set
{
if (_code != value)
{
_code = value;

NotifyPropertyChanged(" Code");
}
}
}

public string Name
{
get
{
Console.WriteLine("Got 'Name' at {0}", DateTime.Now);
return _name;
}
set
{
if (_name != value)
{
_name = value;

NotifyPropertyChanged("Name");
}
}
}

public string Address
{
get
{
Console.WriteLine("Got 'Address' at {0}",
DateTime.Now);
return _address;
}
set
{
_address = value;
}
}

private void NotifyPropertyChanged(string Name)
{

if (PropertyChanged != null)
{
PropertyChanged(this, new
PropertyChangedEventArgs(Name));
}
}
#region INotifyPropertyChanged Members

public event PropertyChangedEventHandler PropertyChanged;

#endregion
}

[John Greenwood]

Hi,
Thanks for the response, but the INotifyPropertyChanged is an
interface, providing your own classes with the abilbity to trigger an
event telling the form to rebind a property. Problem is, regardless of
the property specified in the event, all the forms controls are
rebound.

On Thu, 18 Jan 2007 09:34:31 -0600, "AMDRIT" <am****@hotmail.com>
wrote:

>I would think that propertychanged means that it already happened, while
propertychanging gives you the opportunity to stop it.

take a look at how formclosing and formclosed behave.

"John Greenwood" <jo************@bhpit.co.ukwrote in message
news:2d********************************@4ax.com.. .

>Hi,

I'm not sure if i'm misunderstanding how INotifyPropertyChanged should
work but it's not working as I expected.

I have a sample program with a very simple 'Customer' class with three
properties code, name & address. All these are bound to a form via a
BindingSource and fire the PropertyChanged event when the property is
modified.

I change one of these properties in code and find that all of the
properties are fetched and rebound to the form. Is this correct ?
What's the point of specifying a property name in the
PropertyChangedEventArgs if all the controls are rebound anyway.

Any help would be much appreciated

John

If it's any help my code is below

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

namespace NotifyChange
{
public partial class Form1 : Form
{
private Customer _customer;

public Form1()
{
InitializeComponent();
_customer = new Customer();
_customer.Code = "G001";
_customer.Name = "Greenwood Enterpises Ltd";
_customer.Address = "128 Smithey Road";
customerBindingSource.DataSource = _customer;
}

private void button1_Click(object sender, EventArgs e)
{
Console.WriteLine("<-- Change Code --");

_customer.Code = "F001";

Console.WriteLine("-- Change Code -->");
}

private void button2_Click(object sender, EventArgs e)
{
Console.WriteLine("<-- Change Name --");

_customer.Name = "Fletcher Business Services Ltd";

Console.WriteLine("-- Change Name -->");
}

}

public class Customer : INotifyPropertyChanged
{

private string _code = "";
private string _name = "";
private string _address = "";

public string Code
{
get
{
Console.WriteLine("Got 'Code' at {0}", DateTime.Now);
return _code;
}
set
{
if (_code != value)
{
_code = value;

NotifyPropertyChanged(" Code");
}
}
}

public string Name
{
get
{
Console.WriteLine("Got 'Name' at {0}", DateTime.Now);
return _name;
}
set
{
if (_name != value)
{
_name = value;

NotifyPropertyChanged("Name");
}
}
}

public string Address
{
get
{
Console.WriteLine("Got 'Address' at {0}",
DateTime.Now);
return _address;
}
set
{
_address = value;
}
}

private void NotifyPropertyChanged(string Name)
{

if (PropertyChanged != null)
{
PropertyChanged(this, new
PropertyChangedEventArgs(Name));
}
}
#region INotifyPropertyChanged Members

public event PropertyChangedEventHandler PropertyChanged;

#endregion
}