dropdownlist in gridview row data bound is not executing properly - asp.net

Question

I have a dropdownlist in my gridview. The datas in dropdownlist are "Y" and "N".These two letters. If I select Y then the cell value 6 will be need to become zero. But its not working. Here is my code.
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
DropDownList DropDownList3=(DropDownList)e.Row.FindControl("DropDownList");
//if (DropDownList3 == null)
//if (DropDownList3.SelectedValue == "Y")
if(DropDownList3.SelectedItem.Text == "Y")
{
e.Row.Cells[6].Text = "0";
}
else
{
e.Row.Cells[6].Text = "1";
}
}
}
This is my dropdowlist template field
<asp:TemplateField HeaderText="Alt">
<EditItemTemplate>
<asp:DropDownList ID="DropDownList3" runat="server" >
<asp:ListItem>Y</asp:ListItem>
<asp:ListItem>N</asp:ListItem>
</asp:DropDownList>
</EditItemTemplate>
<FooterTemplate>
<asp:DropDownList ID="DropDownList3" runat="server" >
<asp:ListItem>Y</asp:ListItem>
<asp:ListItem>N</asp:ListItem>
</asp:DropDownList>
</FooterTemplate>
<ItemTemplate>
<asp:DropDownList ID="DropDownList3" runat="server" >
<asp:ListItem>Y</asp:ListItem>
<asp:ListItem>N</asp:ListItem>
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateField>

Answer 1

First, You have to set AutoPostBack="true" for DropDownList3, and You have to create EventHandler for ddl, but in RowCreated not in RowDataBound.
There is example (it's vb.net) :
aspx:
<asp:TemplateField HeaderText="Alt">
<ItemTemplate>
<asp:DropDownList ID="DropDownList3" runat="server" AutoPostBack="true">
<asp:ListItem>Y</asp:ListItem>
<asp:ListItem>N</asp:ListItem>
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateField>
and then, code behind :
Private Sub GridView1_RowCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles grid1.RowCreated
If e.Row.RowType = DataControlRowType.DataRow Then
Dim ddl As DropDownList = CType(e.Row.FindControl("DropDownList3"), DropDownList)
AddHandler ddl.SelectedIndexChanged, AddressOf ddlChange
End If
End Sub
Private Sub ddlChange(ByVal sender As Object, ByVal e As EventArgs)
Dim ddl As DropDownList = DirectCast(sender, DropDownList)
Dim row As GridViewRow = ddl.NamingContainer
If ddl.SelectedItem.Text = "Y" Then
row.Cells(6).Text = "0"
Else
' do what You want
End If
End Sub
It's very important You don't bind Your GridView after every PostBack, and, of course, EnableViewState must be set to True.
Since I'm working in vb.net, I'll try to convert this code into c#.
Update :
There is c# code (I used online converter) :
private void GridView1_RowCreated(object sender, System.Web.UI.WebControls.GridViewRowEventArgs e) {
if ((e.Row.RowType == DataControlRowType.DataRow)) {
DropDownList ddl = ((DropDownList)(e.Row.FindControl("DropDownList3")));
ddl.SelectedIndexChanged += new System.EventHandler(this.ddlChange);
}
}
private void ddlChange(object sender, EventArgs e) {
DropDownList ddl = ((DropDownList)(sender));
GridViewRow row = ddl.NamingContainer;
if ((ddl.SelectedItem.Text == "Y")) {
row.Cells[6].Text = "0";
} else {
// do what You want
}
}