Hide GridView Columns if all rows are Null in ASP.Net

smile says:

<asp:BoundField DataField = '+@cols +' HeaderText = "'+@cols+'" />

No you cant pass columnname line this.

You need to first set AutoGenerateColumns="false" for GridView and remove the columns you added in gridview.

Then add BoundField columns based on the DataTable Columns.

Then you can check the condition for hiding the null columns.

HTML

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false">
</asp:GridView>

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[] { new DataColumn("Name", typeof(string)), new DataColumn("City", typeof(string)), new DataColumn("Country", typeof(string)) });
        dt.Rows.Add("Ram", "Mumbai", "");
        dt.Rows.Add("Rahim", "Rampur", null);
        dt.Rows.Add("Abdul", "Lucknow", "");
        GridView1.DataSource = dt;
        GridView1.Columns.Clear();
        foreach (DataColumn column in dt.Columns)
        {
            BoundField field = new BoundField();
            field.DataField = column.ColumnName;
            field.HeaderText = column.ColumnName;
            GridView1.Columns.Add(field);
        }
        GridView1.DataBind();
        for (int i = 0; i < GridView1.Columns.Count; i++)
        {
            bool allRowNull = true;
            for (int j = 0; j < GridView1.Rows.Count; j++)
            {
                string text = GridView1.Rows[j].Cells[i].Text;
                if (text != "&nbsp;")
                {
                    allRowNull = false;
                    break;
                }
            }
            if (allRowNull)
            {
                GridView1.Columns[i].Visible = false;
            }
        }
    }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim dt As DataTable = New DataTable()
        dt.Columns.AddRange(New DataColumn() {
                            New DataColumn("Name", GetType(String)),
                            New DataColumn("City", GetType(String)),
                            New DataColumn("Country", GetType(String))
        })
        dt.Rows.Add("Ram", "Mumbai", "")
        dt.Rows.Add("Rahim", "Rampur", Nothing)
        dt.Rows.Add("Abdul", "Lucknow", "")
        GridView1.DataSource = dt
        GridView1.Columns.Clear()

        For Each column As DataColumn In dt.Columns
            Dim field As BoundField = New BoundField()
            field.DataField = column.ColumnName
            field.HeaderText = column.ColumnName
            GridView1.Columns.Add(field)
        Next

        GridView1.DataBind()

        For i As Integer = 0 To GridView1.Columns.Count - 1
            Dim allRowNull As Boolean = True

            For j As Integer = 0 To GridView1.Rows.Count - 1
                Dim text As String = GridView1.Rows(j).Cells(i).Text

                If text <> "&nbsp;" Then
                    allRowNull = False
                    Exit For
                End If
            Next

            If allRowNull Then
                GridView1.Columns(i).Visible = False
            End If
        Next
    End If
End Sub

Screenshot