CODEWITHSUNDEEP
c#comboboxselecteditemselectedvalueselectedindexchanged
maxy
maxy

Reputation: 483

Getting selected value of a combobox

public class ComboboxItem { 
            public string Text { get; set; } 
            public string Value { get; set; }
            public override string ToString() { return Text; } 
        }

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            int selectedIndex = comboBox1.SelectedIndex;
            int selecteVal = (int)comboBox1.SelectedValue; 
            ComboboxItem selectedCar = (ComboboxItem)comboBox1.SelectedItem;
            MessageBox.Show(String.Format("Index: [{0}] CarName={1}; Value={2}", selectedIndex, selectedCar.Text, selecteVal));
        }

I'm adding them like:

ComboboxItem item = new ComboboxItem();
                    item.Text = cd.Name;
                    item.Value = cd.ID;
                    this.comboBox1.Items.Add(item);

I keep getting a NullReferenceExeption and not sure why. the text seems to show up just fine.

Upvotes: 48

Views: 378876

Answers (8)

Peyman Majidi
Peyman Majidi

Reputation: 1985

I found a way to cast combobox value to a custom type,
if you do like this the code is still IntelliSense(code suggestion is enable)

When you want to set values

    comboBox1.ValueMember = "ComboValue";
    comboBox1.DisplayMember = "ComboName";

    comboBox1.Items.Add(new
    {
        ComboValue= myCustomTypeInstanse,
        ComboName = myCustomType.Blah.Blah
    });

When you want to get back value of a custom type(your own class)

    var item = (dynamic)comboBox1.SelectedItem; // anonymous to dynamic
    var myCustomType= (CustomType)item.ComboValue; // <-- type casting
    MessageBox.Show(myCustomType.Blah.Blah);

Upvotes: 0

Prabodha
Prabodha

Reputation: 680

You have to cast the selected item to your custom class (ComboboxItem) Try this:

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
ComboBox cmb = (ComboBox)sender;
            int selectedIndex = cmb.SelectedIndex;
            string selectedText = this.comboBox1.Text;
            string selectedValue = ((ComboboxItem)cmb.SelectedItem).Value.ToString();

ComboboxItem selectedCar = (ComboboxItem)cmb.SelectedItem;
MessageBox.Show(String.Format("Index: [{0}] CarName={1}; Value={2}", selectedIndex, selectedCar.Text, selecteVal));

}

Upvotes: 2

Hakan Murat Aks&#252;t
Hakan Murat Aks&#252;t

Reputation: 17

Try this:

int selectedIndex = comboBox1.SelectedIndex;
comboBox1.SelectedItem.ToString();
int selectedValue = (int)comboBox1.Items[selectedIndex];

Upvotes: 0

Jalal Said
Jalal Said

Reputation: 16162

You are getting NullReferenceExeption because of you are using the cmb.SelectedValue which is null. the comboBox doesn't know what is the value of your custom class ComboboxItem, so either do:

ComboboxItem selectedCar = (ComboboxItem)comboBox2.SelectedItem;
int selecteVal = Convert.ToInt32(selectedCar.Value);

Or better of is use data binding like:

ComboboxItem item1 = new ComboboxItem();
item1.Text = "test";
item1.Value = "123";

ComboboxItem item2 = new ComboboxItem();
item2.Text = "test2";
item2.Value = "456";

List<ComboboxItem> items = new List<ComboboxItem> { item1, item2 };

this.comboBox1.DisplayMember = "Text";
this.comboBox1.ValueMember = "Value";
this.comboBox1.DataSource = items;

Upvotes: 15

Tariq Nawaz Khan
Tariq Nawaz Khan

Reputation: 11

The problem you have with the SelectedValue is not converting into integer. This is the main problem so usinge the following code snippet will help you:

int selectedValue;
bool parseOK = Int32.TryParse(cmb.SelectedValue.ToString(), out selectedValue);

Upvotes: 0

Vikas4u
Vikas4u

Reputation: 51

Try this:

private void cmbLineColor_SelectedIndexChanged(object sender, EventArgs e)
    {
        DataRowView drv = (DataRowView)cmbLineColor.SelectedItem;
        int selectedValue = (int)drv.Row.ItemArray[1];
    }

Upvotes: 0

Jason Cidras
Jason Cidras

Reputation: 507

I had a similar error, My Class is

public class ServerInfo
{
    public string Text { get; set; }
    public string Value { get; set; }
    public string PortNo { get; set; }

    public override string ToString()
    {
        return Text;
    }
}

But what I did, I casted my class to the SelectedItem property of the ComboBox. So, i'll have all of the class properties of the selected item.

// Code above
ServerInfo emailServer = (ServerInfo)cbServerName.SelectedItem;

mailClient.ServerName = emailServer.Value;
mailClient.ServerPort = emailServer.PortNo;

I hope this helps someone! Cheers!

Upvotes: 7

James Hill
James Hill

Reputation: 61872

Try this:

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    ComboBox cmb = (ComboBox)sender;
    int selectedIndex = cmb.SelectedIndex;
    int selectedValue = (int)cmb.SelectedValue;

    ComboboxItem selectedCar = (ComboboxItem)cmb.SelectedItem;
    MessageBox.Show(String.Format("Index: [{0}] CarName={1}; Value={2}", selectedIndex, selectedCar.Text, selecteVal));        
}

Upvotes: 53

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