CODEWITHSUNDEEP
c#winforms
Kiran
Kiran

Reputation: 8538

Set Null value in DateTimePicker in C#

I am developing a winform based Desktop application in C#. I would like the user to set the DateTimePicker to Null. I am developing a search box, and would like to ignore the date if it is set to Null

Here is what I am doing : 

     this.dateTimePicker2.CustomFormat = " ";
     this.dateTimePicker2.Format = DateTimePickerFormat.Custom;

     private void dateTimePicker2_ValueChanged(object sender, EventArgs e)
     {
         this.dateTimePicker2.CustomFormat = "dd-MM-yy";
     }

So far so good. However, once the user selects the date, the dateTimePicker2 control shows some date ( the date the user has selected). There is no way to set the date to null again. I am not keen to enable the checkbox associated with the datetimepicker control.

I was wondering if it is possible to set the datetimepicker date to null.

Thanks

Upvotes: 4

Views: 47425

Answers (7)

Dean Lafferty
Dean Lafferty

Reputation: 5

This implementation replaces the original Value property with a nullable DateTime which handles the CheckBox state in the setter. The default date can be set flexibly, in my circumstance a start of year date is easier to work with then min value or today. Setting a custom format of " " when null i felt doesn't improve to user experience but feel free to change, I chose to keep it simple.

public class DateTimePickerAdvanced : DateTimePicker
{
    public DateTime DefaultDate { get; set; }

    public DateTimePickerAdvanced()
    {
        DefaultDate = new DateTime(2020, 01, 01);
    }

    public new DateTime? Value
    {
        get
        {
            return this.ShowCheckBox && !this.Checked ? null : (DateTime?)base.Value;
        }
        set
        {
            if (value == null && !this.ShowCheckBox)
            {
                throw new Exception("ShowCheckBox must be enabled in order to set DateTimePicker to null");
            }

            base.Value = value == null ? DefaultDate : (DateTime)value;

            if (this.ShowCheckBox)
            {
                if (value == null && this.Checked)
                {
                    this.Checked = false;
                }
                else if (value != null && !this.Checked)
                {
                    this.Checked = true;
                }
            }
        }
    }
}

Upvotes: 0

Sagin Joy
Sagin Joy

Reputation: 51

Add checkbox to your datetime picker property:

string datevalue = dateTimePicker2.Checked != true ? "N/A": dateTimePicker2.Text;**

Upvotes: 4

Dave Stuart
Dave Stuart

Reputation: 547

This worked for me when using a DateTimeControl on a SharePoint Application Page.

if (dtcOpenDate.SelectedDate != DateTime.Now)
{
    item["Open Date"] = dtcOpenDate.SelectedDate;    
}

Upvotes: 0

Praditha
Praditha

Reputation: 1172

DateTime is not nullable type.

But you can do this trick:
Just add a checkbox on the date picker, you can find it on properties and set ShowCheckBox to True.
You can use this conditional:

if(datePicker.Checked){
    //Do some stuff to ignore the Date Picker value
}

For additional info, I'm use Microsoft Visual Studio 2010, I'm not check the other IDE yet.
Hope this help.
Cheers...

Upvotes: 0

Dennis
Dennis

Reputation: 37770

I was wondering if it is possible to set the datetimepicker date to null

There's no way to set DateTimePicker.Value to null, because its type isn't nullable. MSDN says, that:

If the Value property has not been changed in code or by the user, it is set to the current date and time (DateTime.Now).

But this isn't a problem. You should set to null some bound property, not the DateTimePicker.Value:

public class MyModel : INotifyPropertyChanged
{
    public DateTime? DateTimeFilter
    {
        get { return dateTimeFilter; }
        set
        {
            if (dateTimeFilter != value)
            {
                dateTimeFilter = value;
                OnPropertyChanged("DateTimeFilter");
            }
        }
    }
    private DateTime? dateTimeFilter;        

    // INotifyPropertyChanged implementation is omitted
}

public partial class Form1 : Form
{
    private readonly MyModel model;

    public Form1()
    {
        InitializeComponent();

        model = new MyModel();
        dateTimePicker1.DataBindings.Add("Value", model, "DateTimeFilter", true, DataSourceUpdateMode.OnPropertyChanged, DateTime.Now);
    }

    private void button1_Click(object sender, EventArgs e)
    {
        MessageBox.Show(model.DateTimeFilter.HasValue ? string.Format("User has selected '{0}'.", model.DateTimeFilter) : "User hasn't selected anything.");
    }

    private void button2_Click(object sender, EventArgs e)
    {
        // here's the data binding magic: our model's property becomes null, 
        // and datetimepicker's value becomes DateTime.Now, as it was initially set
        model.DateTimeFilter = null;
    }
}

Upvotes: 1

MethodMan
MethodMan

Reputation: 18853

This is in reference from a post that is old but other users on this site have posted it here you go

// 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;

or you can set the CustomFormat to " " an empty space like the following below

dateTimePicker1.CustomFormat= " ";

Upvotes: 5

sa_ddam213
sa_ddam213

Reputation: 43616

I dont think its possible because DateTime is not nullable.

But you could use DateTime.MinValue this way tou can still compare easily

if (datetimepicker.DateTime == DateTime.MinValue)
{
  // just as good as null, maybe
}

Upvotes: 1

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