CODEWITHSUNDEEP
c#postgresqlcomboboxdatatable
dbncourt
dbncourt

Reputation: 580

ComboBox.ValueMember and DisplayMember

How do i set this values? I have a DataTable with all the data i want to set in the combobox, but i cant find how to set it.

I tried

ComboBox1.DataSource = dataTable;
ComboBox1.ValueMember = "id"; // --> once hes here, he just jumps out the method
ComboBox1.DisplayMember = "name";

No compilation error, warning, nothing.. just jumps out!

This is the query to fill the DataTable

"Select * from \"Table\""

I checked with the debugger and the datatable was filled. The columns names are "id" and "name". ComboBox is blank. I'm filling it for the first time!

Upvotes: 13

Views: 138973

Answers (10)

Bir Yazilim
Bir Yazilim

Reputation: 13

by combining the given examples and adding the Select_Action for the ToolStripComboBox:

private void Combobox_SelectedIndexChanged(object? sender, EventArgs e)
{
    string colorIdx = ((System.Tuple<int, string>)((ComboBox)sender).SelectedItem).Item1;
    string colorName = ((System.Tuple<int, string>)((ComboBox)sender).SelectedItem).Item2;
}

private void AddItemsToComboBox()
{
    var myItems = new List<Tuple<int, string>>()
        {
            Tuple.Create(0, "Black"),
            Tuple.Create(1, "White"),
            Tuple.Create(2, "Red")
        };
    combobox.ComboBox.DataSource = myItems;
    combobox.ComboBox.ValueMember = "Item1";
    combobox.ComboBox.DisplayMember = "Item2";
}

Upvotes: 0

IngoB
IngoB

Reputation: 2969

Maybe not exactly the described issue but in my case the type name was shown in the ComboBox, not the DisplayValue, although everything seemed to be wired up correctly. It then turned out that the type's public properties were defined without getter and setter! :)

Upvotes: 0

flodis
flodis

Reputation: 1221

Using keyvalue pairs to populate a combobox

A neat way to populate combo boxes is to set the datasource to a list of keyvalue pairs. It may also inspire using data stored in a list of some kind:

//Some values to show in combobox
string[] ports= new string[3] {"COM1", "COM2", "COM3"};

//Set datasource to string array converted to list of keyvaluepairs
combobox.Datasource = ports.Select(p => new KeyValuePair<string, string>(p, p)).ToList();

//Configure the combo control
combobox.DisplayMember = "Key";
combobox.ValueMember = "Value";
combobox.SelectedValue = ports[0];

The datasource can be populated using this syntax as well:

ports.Select(p => new { Key = p, Value = p }).ToList();

The technicue may be expanded with more property names for multiple column lists.

Objects that are already key-value pairs like Dictionary items can be used directly

combobox.DataSource = new Dictionary<int, string>()
{
    {0, "COM1"},
    {1, "COM2"},
    {2, "COM3"},
}.ToList();
combobox.ValueMember = "Key";
combobox.DisplayMember = "Value";

Tuples can be initialized and used like this

var ports= new List<Tuple<int, string>>()
{
    Tuple.Create(0, "COM1"),
    Tuple.Create(1, "COM2"),
    Tuple.Create(2, "COM3")
};

combobox.DataSource = ports;
combobox.ValueMember = "Item1";
combobox.DisplayMember = "Item2";

Upvotes: 9

abdellah
abdellah

Reputation: 21

ComboBox1.ValueMember = dataTable.Columns["id"].ColumnsName;   // column name which the values are not visible 
ComboBox1.DisplayMember = dataTable.Columns ["name"].ColumnsName;
 /* 
       column name that you need to select item by proprity : 
ComboBox1.SelectedItem; 
Or   you can use easly this : 
ComboBox1.Text; 
*/

ComboBox1.DataSource= dataTable; //the data table which contains data 
// and this should be last :)

Upvotes: 2

Visitor
Visitor

Reputation: 411

You should not set datasource of your listbox and/or combobox in this order

ComboBox1.DataSource = dataTable;

ComboBox1.ValueMember = "id"; 

ComboBox1.DisplayMember = "name";

Instead, this is correct order:

ComboBox1.ValueMember = "id"; 

ComboBox1.DisplayMember = "name";

ComboBox1.DataSource = dataTable;

NOTE: setting datasource should be last line.

If you set datasource first, SelectedIndexChanged event will fire and you may get the cast error or other exception.

Upvotes: 41

Felipe Leal Cruz
Felipe Leal Cruz

Reputation: 21

I had the same trouble. In my case, SelectedIndexChanged event fires and just jumps out the method. Try do not use SelectedIndexChanged event. Or something like this:

ComboBox1.SelectedIndexChanged -= new System.EventHandler(ComboBox1_SelectedIndexChanged); 
ComboBox1.DataSource = dataTable; 
ComboBox1.ValueMember = "id";  
ComboBox1.DisplayMember = "name";
ComboBox1.SelectedIndexChanged += new System.EventHandler(ComboBox1_SelectedIndexChanged);

It worked for me. =)

Upvotes: 2

oKAN
oKAN

Reputation: 11

public class ComboDeger {
    private string yazi;
    private int deger;
    public ComboDeger(string stryazi, int strdeger) {
        this.yazi = stryazi;
        this.deger = strdeger;
    }
    public string yazisi {
        get {
            return yazi;
        }
    }
    public int degeri {
        get {
            return deger;
        }
    }
}
private void combobox_doldur() {
    ArrayList ComboDegerleri = new ArrayList();
    ComboDegerleri.Add(new ComboDeger("9 : NORMAL", 9));
    ComboDegerleri.Add(new ComboDeger("10 : ENGELLİ", 10));
    comboBox1.DataSource = ComboDegerleri;
    comboBox1.DisplayMember = "yazisi";
    comboBox1.ValueMember = "degeri";
}
private void Form3_Load(object sender, EventArgs e) {
    con.Open();
    combobox_doldur();

    // Populate the COMBOBOX using an array as DataSource.
}

Upvotes: 1

PraveenVenu
PraveenVenu

Reputation: 8337

  ComboBox1.DataSource= dt; //the data table which contains data
  ComboBox1.ValueMember = "id";   // column name which you want in SelectedValue
  ComboBox1.DisplayMember = "name"; // column name that you need to display as text

Upvotes: 3

Glory Raj
Glory Raj

Reputation: 17691

you could specify like this 

  ComboBox1.ValueMember = "id";  
  ComboBox1.DisplayMember = "name";

Upvotes: 0

Austin Salonen
Austin Salonen

Reputation: 50215

They take strings...

ComboBox1.ValueMember = "id"; 
ComboBox1.DisplayMember = "name";

Upvotes: 2

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