set value in combobox inside datagridview

Question

I Have Datagridview with combobox inside and i can't set the index in code I read this and this - both not work.

here is my code:

  dgShuffle.DataSource = dtCards;
  DataGridViewComboBoxColumn cmb = new DataGridViewComboBoxColumn();
  cmb.HeaderText = "Select Data";
  cmb.Name = "cmb";
  cmb.MaxDropDownItems = 2;
  cmb.Items.Add("real");
  cmb.Items.Add("sham");

  dgShuffle.Columns.Add(cmb);
  for (int i = 0; i < dgShuffle.RowCount; i++)
  {
       (dgShuffle.Rows[i].Cells[6] as DataGridViewComboBoxCell).Value = "real";
        // dgShuffle.Rows[i].Cells[6].Value = "real";
  }

To set by code i mean : programmatically (depend on the value in datatble). I Dont Get error at all. the value simply not display in the combobox

I checked the index of the combobox and this is correct , below the output from my immediate window:

?dgShuffle.Rows[i].Cells[6]

{DataGridViewComboBoxCell { ColumnIndex=6, RowIndex=0 }} [System.Windows.Forms.DataGridViewComboBoxCell]: {DataGridViewComboBoxCell { ColumnIndex=6, RowIndex=0 }} base: {DataGridViewComboBoxCell { ColumnIndex=6, RowIndex=0 }} AccessibilityObject: {System.Windows.Forms.DataGridViewCell.DataGridViewCellAccessibleObject} ColumnIndex: 6 ContentBounds: {X = 0 Y = 12 Width = 0 Height = 0} ContextMenuStrip: null DefaultNewRowValue: null Displayed: false EditedFormattedValue: "" EditType: {Name = "DataGridViewComboBoxEditingControl" FullName = "System.Windows.Forms.DataGridViewComboBoxEditingControl"} ErrorIconBounds: {X = 0 Y = 0 Width = 0 Height = 0} ErrorText: "" FormattedValue: "" FormattedValueType: {Name = "String" FullName = "System.String"} Frozen: false HasStyle: false InheritedState: Resizable | ResizableSet | Visible InheritedStyle: {DataGridViewCellStyle { BackColor=Color [Window], ForeColor=Color [ControlText], SelectionBackColor=Color [Highlight], SelectionForeColor=Color [HighlightText], Font=[Font: Name=Microsoft Sans Serif, Size=7.8, Units=3, GdiCharSet=177, GdiVerticalFont=False], WrapMode=False, Alignment=MiddleLeft }} IsInEditMode: false OwningColumn: {DataGridViewComboBoxColumn { Name=cmb, Index=6 }} OwningRow: {DataGridViewRow { Index=0 }} PreferredSize: {Width = 43 Height = 26} ReadOnly: false Resizable: true RowIndex: 0 Selected: false Size: {Width = 100 Height = 24} Style: {DataGridViewCellStyle { }} Tag: null ToolTipText: "" Value: null ValueType: {Name = "Object" FullName = "System.Object"} Visible: true

Next try :

I create a new winforms project
Drag datagridview to the default form (from the toolbox)

Copy this code to Form1_Load :

    DataTable dtCards;
    dtCards = new DataTable();
    dtCards.Columns.Add("printedString");
    dtCards.Rows.Add("1");
    dtCards.Rows.Add("2");
    dtCards.Rows.Add("3");
    dtCards.Rows.Add("4");
    dataGridView1.DataSource = dtCards;

    DataGridViewComboBoxColumn cmb = new DataGridViewComboBoxColumn();
    cmb.HeaderText = "Select Data";
    cmb.Name = "cmb";
    cmb.MaxDropDownItems = 2;
    cmb.Items.Add("real");
    cmb.Items.Add("sham");

    dataGridView1.Columns.Add(cmb);
    for (int i = 0; i < dataGridView1.RowCount; i++)
    {
        (dataGridView1.Rows[i].Cells[6] as DataGridViewComboBoxCell).Value = "real";
        // dgShuffle.Rows[i].Cells[6].Value = "real";
    }

What am i missing???

"i can't set the index in code" what do you mean ? what is your goal exactly ? — Antoine Pelletier
Wrap it in a try/catch, do you get an error? I don't understand the need to cast, the code dgShuffle.Rows[i].Cells[6].Value = "real"; should work fine as long as that value is available in the drop-down. — Equalsk
Don't really understand your question. I have just tested your code block and it works fine. Did you set the wrong columns index ? — Nam Bình
Your ComboBoxColumn show, you can change its value on run-time but can not programmatically ? Ps: Still don't see anything wrong in your code. Could you provide other code that affect your DataGridView ? Maybe try deleting your DataGridView and create new one to avoid design-time errors ? — Nam Bình

Fabio Fabio · Accepted Answer · 2015-07-16T10:59:46

You are using datagridview bounded to the data source. You need specify that value in the datasource.

Add value for DataGridViewComboBoxColumn in the data source
Then set DataGridViewComboBoxColumn.DataPropertyName to the name of the column/property of your data source

DataTable dtCards;
dtCards = new DataTable();
dtCards.Columns.Add("printedString");
dtCards.Columns.Add("comboboxValue", typeof(String)); //adding column for combobox
dtCards.Rows.Add("1", "real");
dtCards.Rows.Add("2", "real");
dtCards.Rows.Add("3", "real");
dtCards.Rows.Add("4", "real");


DataGridViewComboBoxColumn cmb = new DataGridViewComboBoxColumn();
cmb.HeaderText = "Select Data";
cmb.Name = "cmb";
cmb.MaxDropDownItems = 2;
cmb.Items.Add("real");
cmb.Items.Add("sham");
cmb.DataPropertyName = "comboboxValue"; //Bound value to the datasource

dataGridView1.Columns.Add(cmb);
dataGridView1.DataSource = dtCards;

set value in combobox inside datagridview

Next try :

1 Answers