Nullable DateTimePicker

A standard DateTimePicker control that enables users to enter null value. The fact that it's not intensively modified ensures that it has no potential errors.

Sample Image - Nullable_DateTimePicker.jpg

Introduction

I had do a research on a DateTimePicker that could enter null value and found a lot of solutions to it. But one major problem with those is that they behave quite different from the standard ones and may have many potential bugs, as a result it took time to test before using in a real application. I just found another simple solution that could solve this problem with a little modification, so it could promise no bugs :-).

Solution

I have overridden the Value property to accept Null value as DateTime.MinValue, while maintaining the validation of MinValue and MaxValue of the standard control. That's all there's to it.

Because it's so simple, there's not much to say about it. Please refer to code for details.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

Pham Minh Tri

Vietnam

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Just what I needed

gemini_dk

4:43 20 Dec '11

This is exactly the way I would like it to work. I tweaked it a bit to be a nullable DateTime.
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Re: Just what I needed

jf64

4:57 25 Jan '12

gemini_dk wrote: This is exactly the way I would like it to work. I tweaked it a bit to be a nullable DateTime. ... then you should post your tweak for others... Regards
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No hour in sql database

cyrilcp

0:16 9 Nov '10

It works!!! Thank's a lot.
If you don't want hour into your sql server field, add this and set datetimepicker format to 'short'

Public Shadows Property Value() As Object
Get
If MyBase.Checked Then
If MyBase.Format = DateTimePickerFormat.Short Then
Return MyBase.Value.Date
Else
Return MyBase.Value
End If
Else
Return System.DBNull.Value
End If
End Get

Set(ByVal Value)
If System.Convert.IsDBNull(Value) Then
MyBase.Checked = False
Else
MyBase.Value = Value
MyBase.Checked = True
End If
End Set
End Property

Validation wrong value fix

PREMSONBABY

4:38 20 May '10

Hi Guys,

I would like to thank to Pham Minh Tri, for this great work, and all the guys contibuted to fixing some issues. I would like to add a "small" fix to this. The problem is when you change the value its fireing the validators if you are using validators.

So as you can see i have added "IsInternalValueChanging", in your validator function just check this is true if its true, dont validate. Else you will get wrong value in your validator function.

public class DateTimePicker : System.Windows.Forms.DateTimePicker
{
private DateTimePickerFormat oldFormat = DateTimePickerFormat.Long;
private string oldCustomFormat = null;
private bool bIsNull = false;

private bool _valueChanging;

public bool IsInternalValueChanging
{
get { return _valueChanging; }
}

public DateTimePicker()
: base()
{

}

public new DateTime Value
{
get
{
if (bIsNull)
return DateTime.MinValue;
else
return base.Value;
}
set
{

if (value == DateTime.MinValue)
{
if (bIsNull == false)
{
oldFormat = this.Format;
oldCustomFormat = this.CustomFormat;
bIsNull = true;
}

this.Format = DateTimePickerFormat.Custom;
this.CustomFormat = " ";
base.OnValueChanged(new EventArgs());
}
else
{
if (bIsNull)
{
this.Format = oldFormat;
this.CustomFormat = oldCustomFormat;
bIsNull = false;
}

if (value < this.MaxDate && value > this.MinDate)
{ base.Value = value; }
else if (value > this.MaxDate)
{ value = this.MaxDate; }
else if (value < this.MinDate)
{ value = this.MinDate; }
}
}
}

protected override void OnCloseUp(EventArgs eventargs)
{
base.OnCloseUp(eventargs);

if (Control.MouseButtons == MouseButtons.None)
{
if (bIsNull)
{
_valueChanging = true;

this.Format = oldFormat;
this.CustomFormat = oldCustomFormat;
bIsNull = false;

_valueChanging = false;
}
}
}

protected override void OnKeyDown(KeyEventArgs e)
{
base.OnKeyDown(e);
if (e.KeyCode == Keys.Delete)
{
this.Value = DateTime.MinValue;
}
else if (this.Value == DateTime.MinValue || this.Value == null)
{
_valueChanging = true;
if (e.KeyCode == Keys.Space || e.KeyCode == Keys.Up || e.KeyCode == Keys.Down || e.KeyCode == Keys.Right || e.KeyCode == Keys.Left)
{
this.Value = DateTime.Today;
}
else if ((Char.IsNumber((char)e.KeyValue) && e.KeyValue != 48)
//<-- "0" correction
|| (e.KeyValue >= 97 && e.KeyValue <= 105)) //<-- NumPad1 - NumPad9
{
int typedDigit = 1;
if (e.KeyValue >= 97 && e.KeyValue <= 105) //<-- NumPad1 - NumPad9 must be calculated to numeric KeyValues
{
typedDigit = int.Parse(((char)(e.KeyValue - 48)).ToString());
}
else //if (Char.IsNumber((char)e.KeyValue))
{
typedDigit = int.Parse(((char)e.KeyValue).ToString());
}
this.Value = new DateTime(DateTime.Today.Year, DateTime.Today.Month, typedDigit); //<-- this allows international format of the datetimepicker
SendKeys.Send(typedDigit.ToString()); //<-- this allows typing two digits at once without typing it again as example "12" or "27"
}
_valueChanging = false;
}
}
}

Regards,
Premson.

Re: Validation wrong value fix

oliwan

12:16 30 Sep '10

Hi,

I added a NullableValue property that allows data binding. I also added some code
to show the user when the control has the focus when the date is null (Nothing in
VB) by showing a "|" which looks almost like a cursor. I also improved the behavior
when the user starts typing in the empty field.

public class NullableDateTimePicker : DateTimePicker
{
	private DateTimePickerFormat _oldFormat = DateTimePickerFormat.Long;
	private string _oldCustomFormat;
	private bool _dateIsNull;
 
	private bool _isInternalValueChanging;
	public bool IsInternalValueChanging { get { return _isInternalValueChanging; } }
 
	public NullableDateTimePicker()
		: base()
	{
	}
 
	[Bindable(true)]
	[Category("Behavior")]
	[Description("The current nullable date/time value for this control")]
	public DateTime? NullableValue
	{
		get
		{
			if (_dateIsNull) {
				return null;
			}
			return base.Value;
		}
		set
		{
			if (value.HasValue) {
				Value = value.Value;
			} else {
				Value = DateTime.MinValue;
			}
		}
	}
 
	public new DateTime Value
	{
		get
		{
			if (_dateIsNull)
				return DateTime.MinValue;
			else
				return base.Value;
		}
		set
		{
 
			if (value == DateTime.MinValue) {
				if (!_dateIsNull) {
					_oldFormat = this.Format;
					_oldCustomFormat = this.CustomFormat;
					_dateIsNull = true;
				}
 
				this.Format = DateTimePickerFormat.Custom;
				this.CustomFormat = this.Focused ? "|" : " ";
				base.OnValueChanged(new EventArgs());
			} else {
				if (_dateIsNull) {
					this.Format = _oldFormat;
					this.CustomFormat = _oldCustomFormat;
					_dateIsNull = false;
				}
 
				if (value < this.MaxDate && value > this.MinDate) {
					base.Value = value;
				} else if (value > this.MaxDate) {
					value = this.MaxDate;
				} else if (value < this.MinDate) {
					value = this.MinDate;
				}
			}
		}
	}
 
	protected override void OnCloseUp(EventArgs eventargs)
	{
		base.OnCloseUp(eventargs);
 
		if (Control.MouseButtons == MouseButtons.None) {
			if (_dateIsNull) {
				_isInternalValueChanging = true;
 
				this.Format = _oldFormat;
				this.CustomFormat = _oldCustomFormat;
				_dateIsNull = false;
 
				_isInternalValueChanging = false;
			}
		}
	}
 
	protected override void OnKeyDown(KeyEventArgs e)
	{
		base.OnKeyDown(e);
		if (e.KeyCode == Keys.Delete) {
			this.Value = DateTime.MinValue;
		} else if (_dateIsNull) {
			_isInternalValueChanging = true;
			if (e.KeyCode == Keys.Space || e.KeyCode == Keys.Up || e.KeyCode == Keys.Down || e.KeyCode == Keys.Right || e.KeyCode == Keys.Left) {
				this.Value = DateTime.Today;
			} else if ((Char.IsNumber((char)e.KeyValue) && e.KeyValue != 48) || (e.KeyValue >= 97 && e.KeyValue <= 105)) { //"0" correction, NumPad1 - NumPad9 
				int typedDigit = 1;
				if (e.KeyValue >= 97 && e.KeyValue <= 105) { //<-- NumPad1 - NumPad9 must be calculated to numeric KeyValues 
					typedDigit = int.Parse(((char)(e.KeyValue - 48)).ToString());
				} else { //if (Char.IsNumber((char)e.KeyValue)) 
					typedDigit = int.Parse(((char)e.KeyValue).ToString());
				}
				this.Value = DateTime.Now;
				SendKeys.SendWait("{RIGHT}"); // Selects the day part
				SendKeys.Send(typedDigit.ToString()); // Replaces the date part by the typed digit
			}
			_isInternalValueChanging = false;
		}
	}
 
	protected override void OnGotFocus(EventArgs e)
	{
		base.OnGotFocus(e);
		if (_dateIsNull) {
			CustomFormat = "|"; // Show the user that the NullableDateTimePicker has the Focus by simulating a cursor.
		}
	}
 
	protected override void OnLostFocus(EventArgs e)
	{
		if (_dateIsNull) {
			CustomFormat = " ";
		}
	}
}

--* Oli *--
www.cysoft.ch

Re: Validation wrong value fix

DeuceDude

15:46 28 Oct '11

thanks a lot to the original creator, and you two modifiers. logged in just to say that. This control being bindable is very helpful. note to others, remember to bind your datasource field/column to the "NullableValue" as opposed to the "Value" [found under Data>(DataBindings) section in the "Properties Pane"]
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thank you for your help!

wuhai0809

14:52 5 May '10

thank you for your help!
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Set Nullable DateTimePicker default value [00/00/0000]

tinhleduc

0:27 26 Feb '10

You can set NullFormat to [00/00/0000]

string _NullFormat = "00/00/0000";

public string NullFormat

{

        get { return this._NullFormat; }

        set { this._NullFormat = value; }

}

protected override void OnKeyDown(KeyEventArgs e)

{

	base.OnKeyDown (e);

 

        if (e.KeyCode == Keys.Delete)

        {

                this.Value = DateTime.MinValue;

                this.ValueNullable = null;

                //Backup CustomFormat

                if (this.CustomFormat != _NullFormat) this._OldCustomFormat = this.CustomFormat;

                this.CustomFormat = _NullFormat;

        }

        else

        {

                this.CustomFormat = this._OldCustomFormat; //Restore

        }

}

protected override void OnValueChanged(EventArgs e)

{

      base.OnValueChanged(e);

      this.ValueNullable = base.Value;

}

http://www.sendspace.com/file/8qtjdj[Download Sample]

tinhleduc@gmail.com

Update

Romain TAILLANDIER

22:37 21 Sep '09

Hello,

I use your code, because it is elegant, simple and efficient, as Phil Raevsky said.
I have used all remarks from the forum and found some new upgrades.

public class NullableDateTimePicker : System.Windows.Forms.DateTimePicker
{
    DateTimePickerFormat _Format;
    string _CustomFormat;
    private DateTime? _ValueNullable;
 
    public NullableDateTimePicker()
        : base()
    {
        _Format = base.Format;
        _CustomFormat = base.CustomFormat;
    }
 
    // overrides of this two property 
    // because in case of modifying Format or CustomFormat at runtime, saved values become obsolete, and could be restored

    public new DateTimePickerFormat Format
    {
        get { return base.Format; }
        set { this._Format = value; base.Format = value; }
    }
    public new string CustomFormat
    {
       get { return base.CustomFormat; }
       set { this._CustomFormat = value; base.CustomFormat = value; }
    }
 
    // using the nullable Datetime from alc_aardvark
    public DateTime? ValueNullable
    {
        get 
        { 
            // May be have to test this
            // if(_ValueNullable.HasValue && (_ValueNullable.Value <= this.MinDate || _ValueNullable.Value >= this.MaxDate))
            //     // do something
            return _ValueNullable; 
        }
        set
        {
            _ValueNullable = value;
            // Be carefull of limits, that cause ArgumentOutOfRangeExceptions
            // Limits are not from DateTime, but from this !
            // In this case Over range values, i do as if value was null (for printing)
            if(!_ValueNullable.HasValue || value <= this.MinDate || value >= this.MaxDate) 
            {
                // show nothing in datetime picker
                base.Format = DateTimePickerFormat.Custom;
                base.CustomFormat = " ";
                base.OnValueChanged(EventArgs.Empty);
            }
            else
            {
                // restore printing.
                base.Format = _Format;
                base.CustomFormat = _CustomFormat;
                base.Value = _ValueNullable.Value;
            }
        }
    }
 
    // Override this property to be sure ValueNullable is used.
    public new DateTime Value
    {
        get
        {
            if(!_ValueNullable.HasValue) // if( value == null)
               return this.MinDate; // or DateTime.MinValue
            return ValueNullable.Value;
        }
        set
        {
            this.ValueNullable = value;
        }
    }
 
    protected override void OnKeyDown(KeyEventArgs e) 
    { 
        ... //same as original version
    }
    protected override void OnCloseUp(EventArgs eventargs)
    { 
        ... //same as original version
    }
       
}

Hope that could help.

Romain TAILLANDIER
www.romaintaillandier.blogspot.com
romaintaillandier.free.fr
www.maintag.fr

This is a very insightful approach to the problem

Phil Raevsky

16:01 28 Aug '09

Simple, elegant, and almost perfect
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This one dispaly pink if null date (VB.NET)

Larry Rouse

11:32 28 Aug '09

Imports System
Imports System.Windows.Forms
Namespace Controls
Public Class DateTimePicker
Inherits System.Windows.Forms.DateTimePicker
Private bIsNull As Boolean = False
Private mBackColor As Color = SystemColors.Window
Public Sub New()
MyBase.New()
End Sub
Public Shadows Property Value() As DateTime
Get
If bIsNull Then
Return DateTime.MinValue
Else
Return MyBase.Value
End If
End Get
Set(ByVal value As DateTime)
If value = DateTime.MinValue Or value.Date = "01/01/1905" Or value.Date = "01/01/1900" Then
If bIsNull = False Then bIsNull = True
MakePinkFormat()
Else
MakeWhiteFormat()
bIsNull = False
MyBase.Value = value
End If
End Set
End Property
' Protected Overloads Overrides Sub OnCloseUp(ByVal eventargs As EventArgs)
Protected Overrides Sub OnCloseUp(ByVal eventargs As EventArgs)

If Control.MouseButtons = MouseButtons.None Or Control.MouseButtons = Windows.Forms.MouseButtons.Left Then
Me.Value = MyBase.Value
End If
MyBase.OnCloseUp(eventargs)
End Sub
Protected Overloads Overrides Sub OnKeyDown(ByVal e As KeyEventArgs)
MyBase.OnKeyDown(e)

If e.KeyCode = Keys.Delete Then
Me.Value = DateTime.MinValue
MyBase.Value = "01/01/1905"
End If
End Sub
Private Sub MakePinkFormat()
Me.Format = DateTimePickerFormat.[Custom]
Me.BackColor = Color.Pink
Me.CustomFormat = " "
MyBase.Value = "01/01/1905"
End Sub
Private Sub MakeWhiteFormat()
Me.Format = DateTimePickerFormat.Short
Me.BackColor = Color.White
Me.CustomFormat = Nothing
End Sub
'The BackColor property we will be calling
Public Overrides Property BackColor() As Color
Get
Return mBackColor
End Get
Set(ByVal Value As Color)
mBackColor = Value
'After the BackColor has been set, Invalidate the control
'This will force it to be redrawn
'Me.Invalidate()
End Set
End Property
'WndProc fires durring the painting of the control
Protected Overrides Sub WndProc(ByRef m As Message)
'Check to see if message being send is WM_ERASEBKGND.
'The hex value of this message is &H14.
'This message is sent when the background of the
'object needs to be erased. In our case though, instead of
'erasing it, we will paint a rectangle over it
If m.Msg = CInt(&H14) Then ' WM_ERASEBKGND
Dim g As Graphics = Graphics.FromHdc(m.WParam)
g.FillRectangle(New SolidBrush(mBackColor), ClientRectangle)
g.Dispose()
Return
End If
MyBase.WndProc(m)
End Sub
Private Sub DateTimePicker_EnabledChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.EnabledChanged
Me.CalendarForeColor = Color.Black
End Sub
End Class
End Namespace

This one works! (VB 2008) [modified]

Jeromeyers

12:55 10 Feb '09

This is an edit because I realized, like the previous poster, than you can simply shadow the Value property of the base DateTimePicker to allow Nullable Dates. That means that it works exactly like you would want/expect it to, in databinding situations and everything.

Public Class NullableDateTimeControl
    Inherits System.Windows.Forms.DateTimePicker
 
    Private oldFormat As DateTimePickerFormat = DateTimePickerFormat.Short
    Private oldCustomFormat As String = Nothing
    Private _IsNull As Boolean = False
 

    Public Sub New()
        MyBase.New()
    End Sub
 

    ''' <summary>
    ''' The Date Value of the control (is Nullable, can be set to Nothing).
    ''' </summary>
    ''' <value></value>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Public Shadows Property Value() As Date?
        Get
 
            If Me._IsNull Then
 
                Return Nothing
 
            Else
 
                Return MyBase.Value
 
            End If
 
        End Get
        Set(ByVal newValue As Date?)
 
            If Not newValue.HasValue Then
 
                If Not Me._IsNull Then
 
                    Me.oldFormat = Me.Format
                    Me.oldCustomFormat = Me.CustomFormat
                    Me._IsNull = True
 
                End If
 
                Me.Format = DateTimePickerFormat.Custom
                Me.CustomFormat = " "
 
            Else
 
                If Me._IsNull Then
 
                    Me.Format = Me.oldFormat
                    Me.CustomFormat = Me.oldCustomFormat
                    Me._IsNull = False
 
                End If
 
                MyBase.Value = newValue.Value
 
            End If
 
        End Set
    End Property
 

    ''' <summary>
    ''' Allows the user to select a new date if the control is already null.
    ''' </summary>
    ''' <param name="eventargs"></param>
    ''' <remarks></remarks>
    Protected Overrides Sub OnCloseUp(ByVal eventargs As System.EventArgs)
 
        If Control.MouseButtons = Windows.Forms.MouseButtons.None Then
 
            If Me._IsNull Then
 
                Me.Format = Me.oldFormat
                Me.CustomFormat = Me.oldCustomFormat
                Me._IsNull = False
 
            End If
 
        End If
 
        MyBase.OnCloseUp(eventargs)
 
    End Sub
 

    ''' <summary>
    ''' Overrides the base class implementation to allow the user to create a Null value by pressing the Delete key.
    ''' </summary>
    ''' <param name="e"></param>
    ''' <remarks></remarks>
    Protected Overrides Sub OnKeyUp(ByVal e As System.Windows.Forms.KeyEventArgs)
        MyBase.OnKeyUp(e)
 
        If e.KeyCode = Keys.Delete Then
 
            Me.Value = DateTime.MinValue
 
        End If
 
    End Sub
 

End Class

modified on Wednesday, February 11, 2009 10:51 AM

Re: This one works! (VB 2008)

EMYNA

12:40 28 Oct '09

Hi, i wanna know if this code can be used in visual studio 2008 (visual basic) or i need to make some changes to use them.
Sign In·View Thread·Permalink	3.00/5 (3 votes)

Use the Nullable Datetime for a more updated solution.

chstngs

5:39 7 Oct '08

This way you can actually have a null value for the control.

public new DateTime ? Value
{
get
{
if (bIsNull)
return null;
else
return base.Value;
}
set
{
if (value == null)
{
if (bIsNull == false)
{
oldFormat = this.Format;
oldCustomFormat = this.CustomFormat;
bIsNull = true;
}

this.Format = DateTimePickerFormat.Custom;
this.CustomFormat = " ";
}
else
{
if (bIsNull)
{
this.Format = oldFormat;
this.CustomFormat = oldCustomFormat;
bIsNull = false;
}
base.Value = value.Value;
}
}
}

protected override void OnCloseUp(EventArgs eventargs)
{
if (Control.MouseButtons == MouseButtons.None)
{
if (bIsNull)
{
this.Format = oldFormat;
this.CustomFormat = oldCustomFormat;
bIsNull = false;
}
}
base.OnCloseUp (eventargs);
}

protected override void OnKeyDown(KeyEventArgs e)
{
base.OnKeyDown (e);

if (e.KeyCode == Keys.Delete)
this.Value = null;
}

It's really great! Thank you very much!!

wxpwu

2:48 15 Jun '08


Sign In·View Thread·Permalink	5.00/5 (1 vote)

Small correction

Maxxx333

1:32 16 Nov '06

When used out-of-the-box, the user must use the mouse to enter a date once the value has been set to DateTime.MinValue.

Change the KeyUp override as follows:

protected override void OnKeyUp(KeyEventArgs e)
{
base.OnKeyUp(e);

if (e.KeyCode == Keys.Delete)
this.Value = DateTime.MinValue;

else if (this.Value == DateTime.MinValue
&& (e.KeyCode == Keys.Space || Char.IsNumber((char)e.KeyValue)
|| e.KeyCode == Keys.Up || e.KeyCode == Keys.Down
|| e.KeyCode == Keys.Right || e.KeyCode == Keys.Left))
this.Value = DateTime.Today;
}

This allows the user to get the "normal" date in the box after pressing a space, any arrow key, or any number.

Comments?

Re: Small correction - an enhancement to that correction

ccbt

19:27 9 Sep '09

While this allowed the control to go back to edit mode after it was set to null, I didn't like the way it would go back to Today's date. The reason being... Today is 09/09/09. Well, lets say I want to go into that field and enter in an April date, I will hit 4 and it will display 09/09/2009. I will have to hit 4 again to enter the April date.

I tried moving the base.OnKeyUp(e) call after the code to set today's date so it would persist the 4 into the control and that didn't work. Then I tried moving the code to the OnKeyDown event handler. That didn't work either. So I found away around it be using some date manipulation:

        protected override void OnKeyDown(KeyEventArgs e)
        {
 

            if (e.KeyCode == Keys.Delete)
            {
                this.Value = null;
            }
            else if ((this.Value == DateTime.MinValue || this.Value == null)
                && (e.KeyCode == Keys.Space || Char.IsNumber((char)e.KeyValue)
                || e.KeyCode == Keys.Up || e.KeyCode == Keys.Down
                || e.KeyCode == Keys.Right || e.KeyCode == Keys.Left))
            {
                DateTime newDate = DateTime.Today;
                if (Char.IsNumber((char)e.KeyValue))
                {
                    newDate = DateTime.Parse(string.Format("{0}/{1}/{2}", (char)e.KeyValue, DateTime.Today.Day, DateTime.Today.Year));
                }
                this.Value = newDate;
                
            }
            base.OnKeyDown(e);
 
        }

NOTE: I have also included a check for this.Value == null because I also altered the class to use a Nullable(DateTime). Also, this is in the OnKeyDown event. I moved this from the previously suggested OnKeyUp. I think it will work either way, though.

Re: Small correction - an enhancement to that correction BugFixing =) [modified]

Leonunicorn

1:45 4 Dec '09

Hi there,

I have fixed some bugs and...

extended it to...

- use two digits
- international support
- using numpad

bugs fixed:
- using Zero "0" numeric exception
- always got april
- can't use two digits
- null value exception

       protected override void OnKeyDown(KeyEventArgs e)
        {
            base.OnKeyDown(e);
            if (e.KeyCode == Keys.Delete)
            {
                this.Value = DateTime.MinValue;     //<--- null does not work, so there is the origin value
            }
            else if ((this.Value == DateTime.MinValue || this.Value == null)
                && (e.KeyCode == Keys.Space || (Char.IsNumber((char)e.KeyValue) && e.KeyValue != 48)    //<-- "0" correction
                || e.KeyCode == Keys.Up || e.KeyCode == Keys.Down || e.KeyCode == Keys.Right
                || e.KeyCode == Keys.Left
                || (e.KeyValue >= 97 && e.KeyValue <= 105) //<-- NumPad1 - NumPad9
                ))
            {
 
                int typedDigit = 1;
                if (e.KeyValue >= 97 && e.KeyValue <= 105)
                {//<-- NumPad1 - NumPad9 must be calculated to numeric KeyValues
                    typedDigit = int.Parse(((char)e.KeyValue - 46).ToString());
                }
                else
                {
                    typedDigit = int.Parse(((char)e.KeyValue).ToString());
                }
                
 
                DateTime newDate = DateTime.Today;
                if (Char.IsNumber((char)e.KeyValue))
                {
                    newDate = new DateTime(DateTime.Today.Year, DateTime.Today.Month, typedDigit);    //<-- this allows international format of the datetimepicker
                } 
                this.Value = newDate;
                SendKeys.Send(typedDigit.ToString()); //<-- this allows typing two digits at once without typing it again as example "12" or "27"
            }
            
            
        }

modified on Friday, December 4, 2009 9:02 AM

Re: Small correction - an enhancement to that correction BugFixing x 2 [modified]

kipotlov

6:14 11 Dec '09

I got an exception on this line when i pressed space and the value is null :

typedDigit = int.Parse(((char)e.KeyValue).ToString());

I fixed it like this :

        protected override void OnKeyDown(KeyEventArgs e)
        {
            base.OnKeyDown(e);
            if (e.KeyCode == Keys.Delete)
            {
                this.Value = DateTime.MinValue;
            }
            else if (this.Value == DateTime.MinValue || this.Value == null)
 
            {
                if (e.KeyCode == Keys.Space || e.KeyCode == Keys.Up || e.KeyCode == Keys.Down 
                    || e.KeyCode == Keys.Right || e.KeyCode == Keys.Left)                 
                {
                    this.Value = DateTime.Today;
                }
                else if ((Char.IsNumber((char)e.KeyValue) && e.KeyValue != 48) //<-- "0" correction
                    || (e.KeyValue >= 97 && e.KeyValue <= 105)) //<-- NumPad1 - NumPad9       
                {
                    int typedDigit = 1;
                    if (e.KeyValue >= 97 && e.KeyValue <= 105)    //<-- NumPad1 - NumPad9 must be calculated to numeric KeyValues        
                    {
                        typedDigit = int.Parse(((char)(e.KeyValue - 48)).ToString());
                    }
                    else //if (Char.IsNumber((char)e.KeyValue))
                    {
                        typedDigit = int.Parse(((char)e.KeyValue).ToString());
                    }
 
                    this.Value = new DateTime(DateTime.Today.Year, DateTime.Today.Month, typedDigit); //<-- this allows international format of the datetimepicker

                    SendKeys.Send(typedDigit.ToString()); //<-- this allows typing two digits at once without typing it again as example "12" or "27"         
                }
            }
        }

modified on Friday, December 11, 2009 1:29 PM

Re: Small correction - an enhancement to that correction BugFixing x 2

Leonunicorn

4:57 15 Dec '09

thanks =)

I have fixed an another issue too...

When you enter a date by keyboard and a MaxDate or MinDate is set, it will throw an exception.

I change the code again...

       public new DateTime Value
        {
            get
            {
                if (bIsNull)
                    return DateTime.MinValue;
                else
                    return base.Value;
            }
            set
            {
                if (value == DateTime.MinValue)
                {
                    if (bIsNull == false)
                    {
                        oldFormat = this.Format;
                        oldCustomFormat = this.CustomFormat;
                        bIsNull = true;
                    }
 
                    this.Format = DateTimePickerFormat.Custom;
                    this.CustomFormat = " ";
                }
                else
                {
                    if (bIsNull)
                    {
                        this.Format = oldFormat;
                        this.CustomFormat = oldCustomFormat;
                        bIsNull = false;
                    }
//MinMaxDate fix
                    if (value < this.MaxDate && value > this.MinDate)
                    {
                        base.Value = value;
                    }
                    else if (value > this.MaxDate)
                    {
                        value = this.MaxDate;
                    }
                    else if (value < this.MinDate)
                    {
                        value = this.MinDate;
                    }
                }
            }
        }

Re: Small correction - an enhancement to that correction BugFixing x 2

Leonunicorn

3:42 4 Jan '10

I am back *smile*

Found a bug, when changing the DateTime Value to nothing (DateTime.MinValue) the ValueChanged Event will not be raised, so I put in an Eventraiser...

        public new DateTime Value
        {
            get
            {
                if (bIsNull)
                    return DateTime.MinValue;
                else
                    return base.Value;
            }
            set
            {
                if (value == DateTime.MinValue)
                {
                    if (bIsNull == false)
                    {
                        oldFormat = this.Format;
                        oldCustomFormat = this.CustomFormat;
                        bIsNull = true;
                    }
 
                    this.Format = DateTimePickerFormat.Custom;
                    this.CustomFormat = " ";
                    base.OnValueChanged(new EventArgs());   //Fix to raise a valuechange event when setting the DateTime Value to DateTime.MinValue (faked null)
                }
                else
                {
                    if (bIsNull)
                    {
                        this.Format = oldFormat;
                        this.CustomFormat = oldCustomFormat;
                        bIsNull = false;
                    }
 
                    //MinMaxDate fix
                    if (value < this.MaxDate && value > this.MinDate)
                    {
                        base.Value = value;
                    }
                    else if (value > this.MaxDate)
                    {
                        value = this.MaxDate;
                    }
                    else if (value < this.MinDate)
                    {
                        value = this.MinDate;
                    }
                }
            }
        }

Null Button?

Kysonel

9:48 28 Mar '06

I found this pretty usefull, but do you know a way to place a button in the calendar to place the null value? like the "today" button there is in the lower left corner... I'm using vb.net :P just so you know. thanks!
Sign In·View Thread·Permalink	2.00/5 (5 votes)

How to use?

strent00

5:54 21 Dec '05

The sample project doesn't work for me -- pressing delete does nothing. What gives? How do I use this control in a project? Relative performance is no substitute for absolute achievement.
Sign In·View Thread·Permalink	1.50/5 (12 votes)

Cool!

Super Lloyd

16:36 19 Dec '05

I like it Actually change Value so it is a "DateTime?", much nicer And also I used both Delete & Backspace for having an empty date
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Clicking on current date in dropdown doesn't show datetime

jfk80@wp.pl

2:38 15 Mar '05

When NullableDateTimePicker (NDTP) state is null and it doesn't show value, click on the dropdown and select current value at the bottom of the dropdown, near red circle mark. This should change the NDTP state to not-null and show current DateTime. But NDTP checks if user selected value in dropdown by checking that no mouse button is pressed (in OnCloseUp), which is true only if a calendar was clicked, but not if bottom mark was clicked.
IMO, there is solution for this is not to rely on mouse button state in OnCloseUp. Instead override OnValueChanged and set a flag, then use it in OnCloseUp.
Thus:



		protected override void OnCloseUp(EventArgs eventargs) {

			if (Control.MouseButtons == MouseButtons.None || fHasValueChanged) {

				if (fIsNull) {

					this.Format = fOldFormat;

					this.CustomFormat = fOldCustomFormat;

					fIsNull = false;

				}

				fHasValueChanged = false;

			}

			base.OnCloseUp(eventargs);

		}

		protected override void OnKeyUp(KeyEventArgs e) {

			base.OnKeyUp(e);

			if (e.KeyCode == Keys.Delete) {

				this.Value = DateTime.MinValue;

				this.fHasValueChanged = false;

			}

		}

		protected override void OnValueChanged(EventArgs eventargs) {

			fHasValueChanged = true;

			base.OnValueChanged(eventargs);

		}

Resetting to false in OnKeyUp has to be done, because user can change value by hand, not by dropdown. In such case the flag remains true which could cause problems if user presses delete on NDTP and then pressed and depressed dropdown arrow (without changing value). If flag is not reset when she pressed delete, than suddenly NDTP would show value.