How can I make a DateTimePicker display an empty string

Question

I would like to be able to display a DateTimePicker that has a default value of nothing  i e  no date   For example  I have a start date dtTaskStart and an end date dtTaskEnd for a task  but the end date is not known  and not populated initially   I have specified a custom format of yyyy-MM-dd for both controls   Setting the value to null  or an empty string at runtime causes an error  so how can I accomplish this   I have considered using a checkbox to control the enabling of this field  but there is still the issue of displaying an initial value        Edit  Arguably a duplicate of the question DateTimePicker Null Value   NET   but the solution I found for my problem is not a solution for that question  so I think it should remain here for others to find

User · Answer

When I want to display an empty date value I do this

            if (sStrDate != "")
            {
                dateCreated.Value = DateTime.Parse(sStrDate);
            }
            else
            {
                dateCreated.CustomFormat = " ";
                dateCreated.Format = DateTimePickerFormat.Custom;
            }

Then when the user clicks on the control I have this:

            private void dateControl_MouseDown(object sender, MouseEventArgs e)
            {
                ((DateTimePicker)sender).Format = DateTimePickerFormat.Long;    
            }

This allows you to display and use an empty date value, but still allow the user to be able to change the date to something when they wish.

Keep in mind that sStrDate has already been validated as a valid date string.

User · Answer

Better to use text box for calling displaying date and while saving use DateTimePicker  Make visible property true or false as per requirement   For eg   During form load make Load date in Textbox and make DTPIcker invisible and while adding vice versa

User · Answer

In case anybody has an issue with setting datetimepicker control to blank during the form load event  and then show the current date as needed  here is an example   MAKE SURE THAT CustomFormat          has same number of spaces  at least one space  in both methods  Private Sub setDateTimePickerBlank ByVal dateTimePicker As DateTimePicker           dateTimePicker Visible   True     dateTimePicker Format   DateTimePickerFormat Custom     dateTimePicker CustomFormat           End Sub   Private Sub dateTimePicker MouseHover ByVal sender As Object  ByVal e As                      System EventArgs  Handles dateTimePicker MouseHover      Dim dateTimePicker As DateTimePicker   CType sender  DateTimePicker      If dateTimePicker Text          Then         dateTimePicker Text   Format DateTime Now   MM dd yyyy       End If End Sub

User · Answer

Obfuscating the value by using the CustomFormat property  using checkbox cbEnableEndDate as the flag to indicate whether other code should ignore the value   If dateTaskEnd  gt  Date FromOADate 0  Then     dtTaskEnd Format   DateTimePickerFormat Custom     dtTaskEnd CustomFormat    yyyy-MM-dd      dtTaskEnd Value   dateTaskEnd      dtTaskEnd Enabled   True     cbEnableEndDate Checked   True Else     dtTaskEnd Format   DateTimePickerFormat Custom     dtTaskEnd CustomFormat           dtTaskEnd Value   Date FromOADate 0      dtTaskEnd Enabled   False     cbEnableEndDate Checked   False End If

User · Answer

Just set the property as follows   When the user press  clear button  or  delete key  do  dtpData CustomFormat         An empty SPACE dtpData Format   DateTimePickerFormat Custom   On DateTimePicker1 ValueChanged event do  dtpData CustomFormat    dd MM yyyy hh mm ss

User · Answer

Listen    Make Following changes in your code if you want to show empty datetimepicker and get null when no date is selected by user  else save date    Set datetimepicker FORMAT property to custom  set CUSTOM FORMAT property to empty string      set its TAG to 0 by default  Register Event for datetimepicker VALUECHANGED    Now real work starts  if user will interact with datetimepicker its VALUECHANGED event will be called and there set its TAG property to 1   Final Step  Now when saving  check if its TAG is zero  then save NULL date else if TAG is 1 then pick and save Datetime picker value   It Works like a charm   Now if you want its value be changed back to empty by user interaction  then add checkbox and show text  Clear  with this checkbox  if user wants to clear date  simply again set its CUSTOM FORMAT property to empty string      and set its TAG back to 0  Thats it

User · Answer

The basic concept is the same told by others  But its easier to implement this way when you have multiple dateTimePicker   dateTimePicker1 Value   DateTime Now  dateTimePicker1 ValueChanged    new System EventHandler this Dtp ValueChanged   dateTimePicker1 ShowCheckBox true  dateTimePicker1 Checked false    dateTimePicker2 Value   DateTime Now  dateTimePicker2 ValueChanged    new System EventHandler this Dtp ValueChanged   dateTimePicker2 ShowCheckBox true  dateTimePicker2 Checked false    the value changed event function          void Dtp ValueChanged object sender  EventArgs e                        if   DateTimePicker sender  ShowCheckBox  true                                if   DateTimePicker sender  Checked  false                                          DateTimePicker sender  CustomFormat                              DateTimePicker sender  Format   DateTimePickerFormat Custom                                    else                                         DateTimePicker sender  Format   DateTimePickerFormat Short                                              else                                 DateTimePicker sender  Format   DateTimePickerFormat Short                            When unchecked   When checked

User · Answer

this worked for me for c      if  enableEndDateCheckBox Checked    true        endDateDateTimePicker Enabled   true      endDateDateTimePicker Format   DateTimePickerFormat Short                    else       endDateDateTimePicker Enabled   false      endDateDateTimePicker Format   DateTimePickerFormat Custom      endDateDateTimePicker CustomFormat            nice one guys

[.net] How can I make a DateTimePicker display an empty string?

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