Set DateTimePicker value to be null

Question

I am developing a WinForms UI with two DateTimePicker controls. Initially I want to set the value of the controls to null until a user selects a date. If the user does not select a date, it will pass a value of null to the database.

By default it takes the current date.

Could you plz suggest something or attach a piece of code which will help me out.

I have tried setting the MinDate property but it doesn't work.

The code is in C# .Net.

Thanks, Manali.

Answer 1

I think the best solution is to use the build-in checkbox that tell the user if a value is specified or not.

Set the control property ShowCheckBox = true

When you bind the value to it do something like

 if (value == DateTime.MinValue) {
    datePicker.Checked = false;
  } else {
    datePicker.Checked = true;
    datePicker.Value = value;
  }

When reading back the value check the Checked property.

If you don't like the displayed value when it's unchecked, you can combine that with the other suggestions.

  if (!datePicker.Checked) {
    // hide date value since it's not set
    datePicker.CustomFormat = " ";
    datePicker.Format = DateTimePickerFormat.Custom;
  } else {
    datePicker.CustomFormat = null;
    datePicker.Format = DateTimePickerFormat.Long; // set the date format you want.
  }

Answer 2

I know this is an older post, but others might still find this useful. It is fairly elegant and concise. I used this with a .Net 4.0 DateTimePicker but earlier versions should work with minimal tweaking. It leverages MinDate and Checked.

    // Use ValueChanged to decide if the value should be displayed:
    dateTimePicker1.ValueChanged += (s, e) => { dateTimePicker1.CustomFormat = (dateTimePicker1.Checked && dateTimePicker1.Value != dateTimePicker1.MinDate) ? "MM/dd/yyyy" : " "; };

    //When getting the value back out, use something like the following:
    DateTime? dt = (dateTimePicker1.Checked && dateTimePicker1.Value != dateTimePicker1.MinDate) ?  (DateTime?) dateTimePicker1.Value : null; 
    // or
    DateTime dt2 = (dateTimePicker1.Checked && dateTimePicker1.Value != dateTimePicker1.MinDate) ?  dateTimePicker1.Value : DateTime.MinValue;