Find the right value of textbox

Question

I have a problem with inserting data inserting data into database.

 <asp:Repeater ID="Repeater1" runat="server" DataSourceID="SqlDataSource1"   OnItemDataBound="Repeater1_ItemDataBound">
   <ItemTemplate> 
     <!-- Some other data (text...) -->

     <asp:HiddenField ID="HiddenField1" runat="server" Value='<%# Eval("PostId") %>' />  

     <asp:TextBox ID="txtAddComment" runat="server" CssClass="textbox"  Width="200px" />
     <asp:Button ID="btnAddComment" runat="server" CssClass="button" Text="Comment"   CausesValidation="false" OnClick="btnAddComment_Click"/>
   </ItemTemplate>
</asp:Repeater>

Code behind:

 Protected Sub btnAddComment_Click(sender As Object, e As EventArgs)
        Dim HiddenField1 As HiddenField = DirectCast(Repeater1.Items(0).FindControl("HiddenField1"), HiddenField)
        Dim txtAddComment As TextBox = DirectCast(Repeater1.Items(0).FindControl("txtAddComment"), TextBox)
        Dim conn As New SqlConnection(ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString.ToString)
        Try
            If txtAddComment.Text = "" Then
                Exit Sub
            Else
                conn.Open()
                Dim cmd As SqlCommand = conn.CreateCommand()
                cmd.CommandText = "INSERT INTO Comments (PostId, UserName, CommentText) VALUES (@PostId, @UserName, @Text)"

                cmd.Parameters.Add("PostId", System.Data.SqlDbType.Int).Value = CInt(HiddenField1.Value)
                cmd.Parameters.Add("UserName", System.Data.SqlDbType.NVarChar).Value = Context.User.Identity.Name
                cmd.Parameters.Add("Text", System.Data.SqlDbType.NText).Value = MakeLink(HtmlRemoval.StripTagsCharArray(txtAddComment.Text))                    
                cmd.ExecuteNonQuery()            
            End If

        Catch ex As SqlException                
        Finally
            conn.Close()
        End Try
    End Sub

I display some text, under the text there is textbox and button for comments. I am bounding textId in hiddenfield for inserting comments. The code works fine, but I can only add comment for the first row in database displayed by repeater. When I want to add comment for other rows (2, 3...), the page refreshes and the text in the TextBox stay there.

It is problem with this line of code:

Dim txtAddComment As TextBox = DirectCast(Repeater1.Items(0).FindControl("txtAddComment"), TextBox)

The ID from HiddenField is right. But the code doesn't perform because the line above references for the first textbox on the page and his value is null.

When I change the line of code like this:

  Dim txtAddComment As TextBox = DirectCast(Repeater1.FindControl("txtAddComment"), TextBox)

It returns an error that Object reference not set to an instance of an object.

How to get the right textbox with right value? Thanks for the answer

Answer 1

cast the sender to a button that sent it, then get the textbox from the parent. Example:

Protected Sub button_click(ByVal sender As Object, ByVal e As EventArgs)
   Dim myButton As button= CType(sender, button)
   Dim myTextBox as TextBox = CType(myButton Parent.FindControl("buttonName"), TextBox)

end sub