Nullable DateTimePicker

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

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.

Thanks for this fine code Jeromeyers. I had to make a small modification to make the NullablePicker work. I changed OnKeyUp to set the _IsNull flag to True. (I also made the code responsive to the backspace key.)

VB

Protected Overrides Sub OnKeyUp(ByVal e As System.Windows.Forms.KeyEventArgs)
        MyBase.OnKeyUp(e)
        If e.KeyCode = Keys.Delete OrElse e.KeyCode = Keys.Back Then
            Me._IsNull = True
            Me.Value = Nothing
        End If
End Sub

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;
}

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?

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.

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

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

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;
                    }
                }
            }
        }

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;
            }
        }
    }
}

Thanks
ummanbilisim.com

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!

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.

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

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:

<br />
		protected override void OnCloseUp(EventArgs eventargs) {<br />
			if (Control.MouseButtons == MouseButtons.None || fHasValueChanged) {<br />
				if (fIsNull) {<br />
					this.Format = fOldFormat;<br />
					this.CustomFormat = fOldCustomFormat;<br />
					fIsNull = false;<br />
				}<br />
				fHasValueChanged = false;<br />
			}<br />
			base.OnCloseUp(eventargs);<br />
		}<br />
		protected override void OnKeyUp(KeyEventArgs e) {<br />
			base.OnKeyUp(e);<br />
			if (e.KeyCode == Keys.Delete) {<br />
				this.Value = DateTime.MinValue;<br />
				this.fHasValueChanged = false;<br />
			}<br />
		}<br />
		protected override void OnValueChanged(EventArgs eventargs) {<br />
			fHasValueChanged = true;<br />
			base.OnValueChanged(eventargs);<br />
		}<br />

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.

hi all,

i am using sql server and vb.net 2002 to develop my project.
the problem i face now is when i bind the null value (datatype = datetime) into the date time picker control, it show an error

please help, i need the code in vb.net

loon

Have a nice day

ccloon wrote:
i am using sql server and vb.net 2002 to develop my project.
the problem i face now is when i bind the null value (datatype = datetime) into the date time picker control, it show an error

Have a look at this version of a nullable date time picker.
http://www.omnitalented.com/Blog/PermaLink,guid,9ee757fe-a3e8-46f7-ad04-ef7070934dc8.aspx
It can handle "real" null values as you get them from databases.

You request it in VB. I'm sorry, it's in C#. But it's simple. I'm sure you manage to translate it.

Claudio Grazioli
http://www.grazioli.ch

As I already wrote you, this nullable DateTimePicker[^] can handle null values.

I created a VB.NET version of this control now and you can get it here: nullable DateTimePicker for VB.NET[^]

Claudio
Claudio's Website
Hommingberger Gepardenforelle

I tried this version and binding a nullable datetime does not work, as it leaves the last valid date from a previous bind. Here is a different version that seems to work better. NB. 5 minutes of testing only. Just dataBind to the ValueNullable property as opposed to the Value property if you have a Nullable DateTime. This should work as normal if you have a normal DateTime (bind to Value).

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

namespace Invisage.PinkFloyd.Library.Controls
{
public class DateTimePickerNullable : System.Windows.Forms.DateTimePicker
{
DateTimePickerFormat mOriginaldateTimePickerFormat;
private DateTime? mValueNullable;

public DateTimePickerNullable()
: base()
{
mOriginaldateTimePickerFormat = base.Format;
}

[Category("PinkFloyd")]
[Description("Nullable DateTime")]
[Bindable(true)]
public DateTime? ValueNullable
{
get { return mValueNullable; }
set
{
mValueNullable = value;

if (!mValueNullable.HasValue)
{
this.Format = DateTimePickerFormat.Custom;
this.CustomFormat = " ";
}
else
{
this.Format = mOriginaldateTimePickerFormat;
base.Value = mValueNullable.Value;
}
}
}

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

if (e.KeyCode == Keys.Delete)
{
ValueNullable = null;
}
}
}
}

Have you tried pressing the Delete button when the ValueNullable it is bound? I think you'll find it doesn't work.

Your control could possibly be what I am looking for.

I want to be able to display either a blank space or a customer phrase (such as "No Date Entered" when the date is NULL.

Can your control handle this?

Have a look at this other DateTimePickers, they support that:

NullableDateTimePicker with DateTime.MinDate/DateTime.MaxDate[^] as null value.

NullableDateTimePicker with null[^] as null value.

Claudio
Claudio's Website
Hommingberger Gepardenforelle

Thanks!

Just what I was looking for!
Thank you so much!

Janine Big Grin | :-D

Hi Pham,

First off, excellent control. I have been looking far and wide for something like this, and I thought that I had found my solution in your control, but I am having difficulty placing it in a TabPage on a TabControl control AND data binding.

For example, if I start off with your DateTimePicker control in a TabPage container that is not by default displayed, no problem--I can choose the TabPage and it displays your control fine. Your control operates fine, and I can even set it to "null" (that is, DateTime.MinValue) before selecting the TabPage.

Now add databinding. If I have an additional private DateTime variable and in the form's Load event I add a custom databinding, e.g.

<br />
private DateTime dt = DateTime.MinValue;<br />
<br />
private void Form1_Load(object sender, System.EventArgs e)<br />
{<br />
    this.dateTimePicker1.DataBindings.Add("Value", dt, "");<br />
}<br />

then, when I display the TabPage containing the control, I receive:

An unhandled exception of type 'System.ComponentModel.Win32Exception' occurred in system.windows.forms.dll

Additional information: Error creating window handle.

Do you know any way to prevent this? Debugging seems to reveal that the error occurs somewhere in the Set clause, but I can't pinpoint it--very strange error.

Thanks!
Mark

Nullable DateTimePicker

Introduction

Solution

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