Question

I have a following problem. I have a ListView which returns data from SQL table. One of its columns looks like “Ambient/Trance/Goa Trance/House”.

All i want to do is parse this column and create buttons for each value, for example a button for “Ambient”, a button for “Trance”, etc.

I tried to create buttons in ItemDataBound event in the following way:

    Dim ListView_Albums_PlaceHolder_Artists As PlaceHolder = e.Item.FindControl("ListView_Albums_PlaceHolder_Artists")

    Dim Artists As String() = e.Item.DataItem("album_artists").ToString.Split("/")
    Dim ArtistsN As String() = e.Item.DataItem("album_artists_n").ToString.Split("/")

    Dim ListView_Albums_Literal_Artists As New Literal

    If Artists.Length = 1 Then
        ListView_Albums_Literal_Artists.Text = "Artist: "
    Else
        ListView_Albums_Literal_Artists.Text = "Artists: "
    End If

    ListView_Albums_PlaceHolder_Artists.Controls.Add(ListView_Albums_Literal_Artists)

    For Integer1 As Integer = 0 To Artists.Length - 1
        Dim ListView_Albums_LinkButton_Artist As New LinkButton
        ListView_Albums_LinkButton_Artist.Text = ArtistsN(Integer1)
        ListView_Albums_LinkButton_Artist.CommandName = "Artist"
        ListView_Albums_LinkButton_Artist.CommandArgument = Artists(Integer1)
        ListView_Albums_LinkButton_Artist.CssClass = "a-03"

        ListView_Albums_PlaceHolder_Artists.Controls.Add(ListView_Albums_LinkButton_Artist)

        Dim ListView_Albums_Literal As New Literal
        ListView_Albums_Literal.Text = ", "

        If Not Integer1 = Artists.Length - 1 Then
            ListView_Albums_PlaceHolder_Artists.Controls.Add(ListView_Albums_Literal)
        End If
    Next

They created fine but they didn’t work at all. I tried to Add Handler for Click or Command event but it also didn’t help.

Please help me to solve my problem!

Edit:

As VinayC suggested I changed ItemDataBound to ItemCreated. That helped, but I faced another problem: as far as I understand e.Item.DataItem or, maybe, e.Item becomes Nothing on PostBacks so the buttons do not work.

How to solve that problem? Thanks once again!

Answer 1

So, I solved my problem. The solution wasn’t simple but here it is:

In ItemCreated event I firstly count the number of buttons, then save it to ViewState, and only then I create buttons. I had to save the number of buttons to ViewState because on every postback e.Item.DataItem becomes Nothing.

Maybe there is a simplier solution but I found only that one…

Sub OnItemCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ListViewItemEventArgs)
    Dim ListView_Albums_PlaceHolder_Artists As PlaceHolder = e.Item.FindControl("ListView_Albums_PlaceHolder_Artists")

    If Not ListView_Albums_PlaceHolder_Artists Is Nothing Then
        If Not e.Item.DataItem Is Nothing Then
            ViewState("Length") = e.Item.DataItem("album_artists").ToString.Split("/").Length
        End If

        If Not ViewState("Length") Is Nothing Then
            Dim Length As Integer = ViewState("Length")

            For Integer1 As Integer = 0 To Length - 1
                Dim ListView_Albums_LinkButton_Artist As New LinkButton
                ListView_Albums_LinkButton_Artist.ID = "ListView_Albums_LinkButton_Artist_" & Integer1

                ListView_Albums_PlaceHolder_Artists.Controls.Add(ListView_Albums_LinkButton_Artist)
            Next
        End If
    End If
End Sub

Sub OnItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ListViewItemEventArgs)
    Dim ListView_Albums_PlaceHolder_Artists As PlaceHolder = e.Item.FindControl("ListView_Albums_PlaceHolder_Artists")

    If Not ListView_Albums_PlaceHolder_Artists Is Nothing Then
        If Not e.Item.DataItem Is Nothing Then
            Dim Artists As String() = e.Item.DataItem("album_artists").ToString.Split("/")
            Dim Artists_N As String() = e.Item.DataItem("album_artists_n").ToString.Split("/")

            For Integer1 As Integer = 0 To Artists.Length - 1
                Dim ListView_Albums_LinkButton_Artist As LinkButton = e.Item.FindControl("ListView_Albums_LinkButton_Artist_" & Integer1)

                ListView_Albums_LinkButton_Artist.CommandArgument = Artists(Integer1)
                ListView_Albums_LinkButton_Artist.Text = Artists_N(Integer1)
                ListView_Albums_LinkButton_Artist.CssClass = "a-03"
            Next
        End If
    End If
End Sub