Binding b = new Binding( "Value", person, "BdayNullable", true );
dtBirthdayNullable.DataBindings.Add( b );
b.Format += new ConvertEventHandler( dtBirthdayNullable_Format );
b.Parse += new ConvertEventHandler( dtBirthdayNullable_Parse );
void dtBirthdayNullable_Format( object sender, ConvertEventArgs e )
{
// e.Value is the object value, we format it to be what we want to show up in the control
Binding b = sender as Binding;
if ( b != null )
{
DateTimePicker dtp = (b.Control as DateTimePicker);
if ( dtp != null )
{
if ( e.Value == DBvalue.value )
{
dtp.ShowCheckBox = true;
dtp.Checked = false;
// have to set e.Value to SOMETHING, since it's coming in as NULL
// if i set to DateTime.Today, and that's DIFFERENT than the control's current
// value, then it triggers a CHANGE to the value, which CHECKS the box (not ok)
// the trick - set e.Value to whatever value the control currently has.
// This does NOT cause a CHANGE, and the checkbox stays OFF.
e.Value = dtp.Value;
}
else
{
dtp.ShowCheckBox = true;
dtp.Checked = true;
// leave e.Value unchanged - it's not null, so the DTP is fine with it.
}
}
}
}
void dtBirthdayNullable_Parse( object sender, ConvertEventArgs e )
{
// e.value is the formatted value coming from the control.
// we change it to be the value we want to stuff in the object.
Binding b = sender as Binding;
if ( b != null )
{
DateTimePicker dtp = (b.Control as DateTimePicker);
if ( dtp != null )
{
if ( dtp.Checked == false )
{
dtp.ShowCheckBox = true;
dtp.Checked = false;
e.Value = DBvalue.Value
}
else
{
DateTime val = Convert.ToDateTime( e.Value );
e.Value =val;
}
}
}
}
编辑
我在这里找到了一个好的解决方案:
http://blogs.interknowlogy.com/danhanan/archive/2007/01/21/10847.aspx
还有另一个完美的解决方案:
http://www.mofeel.net/70-microsoft-public-dotnet-framework-windowsforms/8806.aspx