How can I make a DateTimePicker display an empty string?

brass-kazoo_6340 0
Viewed 204828

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..

datetimepicker winforms .net
8 Answers

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 > 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
brass-kazoo_63400

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.

  1. Set datetimepicker FORMAT property to custom.
  2. set CUSTOM FORMAT property to empty string " ".
  3. set its TAG to 0 by default.
  4. 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_66906500

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_134050000
Related