Question

I am trying to traverse the gridview columns in ASP.net web application, using the following code, However the code is not going inside the foreach loop.

// Code snippet to hide columns from a gridview named 'gvEmployees'
gvEmployees.DataSource = dvItems.ToTable();
gvEmployees.DataBind();
string name = "First Name"; //Column name supposed to hide
int index=-1;

foreach (DataColumn col in gvEmployees.Columns)
{
   if (col.ColumnName.ToLower().Trim() == name.ToLower().Trim())
   {
      // Getting the column index if find a match
      index= gvEmployees.Columns.IndexOf(col); 
      // Using the above index, hiding the column from the grid view.
      gvEmployees.Columns[index].Visible = false;
   }

}

I am trying to hide some columns from gridview.

Answer 1

I think u are trying to hide column based on column title so please try following code,

// Code snippet to hide columns from a gridview named 'gvEmployees'
gvEmployees.DataSource = dvItems.ToTable();
gvEmployees.DataBind();
string name = "First Name";// Column name supposed to hide
foreach (var col in gvEmployees.Columns)
{
  if (col.Text.ToLower().Trim() == name.ToLower().Trim())
  {
      // hiding the column from the grid view.
      col.Visible = false;
  }
}

Update

you can also write following code:

string name = "First Name";// Column name supposed to hide
for (int i = 0; i < gvEmployees.Columns.Count; i++)
{
    if (gvEmployees.Columns[i].Text.ToLower().Trim() == name.ToLower().Trim())
    {
        gvEmployees.Columns[i].Visible = false;
    }
}

Update when using auto generated columns (for single-column version),

You need to use the rowdatabound event and hide the cell (column) when the row is bound.

int index = 0;
bool hidden = false;
protected void gvEmployees_RowDataBound(object sender, System.Web.UI.WebControls.GridViewRowEventArgs e)
{
    if(hidden)
    {
         e.Row.Cells[index].Visible =  false;
         return;
    }

    string name = "First Name";// Column name supposed to hide
    for (int i = 0; i < e.Row.Cells.Count; i++)
    {
        if (e.Row.Cells[i].Text.ToLower().Trim() == name.ToLower().Trim())
        {
            e.Row.Cells[i].Visible = false;
            hidden = true;
            index = i;
            break;
        }
    }
}

Update when using auto generated columns, (for multi-column version)

Using the rowdatabound event and hide the cell (column) when the row is bound.

List<int> indexes = new List<int>();
bool hidden = false;
List<string> names = new List<string>();
protected void gvEmployees_RowDataBound(object sender, System.Web.UI.WebControls.GridViewRowEventArgs e)
{
    if(hidden)
    {
         foreach(int index in indexes)
         {
             e.Row.Cells[index].Visible =  false;
         }
    }

    // start - Column names supposed to hide
    // Building the list of column names to be hidden.
    names.Add("First Name");
    names.Add("Last Name");
    names.Add("Address");
    names.Add("ID");
    // end - Column names supposed to hide

    for (int i = 0; i < e.Row.Cells.Count; i++)
    {
        if (names.Contains(e.Row.Cells[i].Text.ToLower().Trim())
        {
            e.Row.Cells[i].Visible = false;
            hidden = true;
            indexes.Add(i);
        }
    }
}