ComboBox.ValueMember和DisplayMember

Question

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!

Answer 1

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.

Answer 2

  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

Answer 3

They take strings...

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

Answer 4

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.
}

Answer 5

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. =)

Answer 6

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.

Answer 7

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 :)

Answer 8

you could specify like this

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