How to send all listview databound data to itemcommand event

Question

I would like to retrieve all listview bound data in code behind when i click a button.

I have tried itemcommand event while using select command although i only able to retrieve the control bound data for this event. whereas i could do with retrieving the itemtemplate bound data as well when transfering to the selectedtemplate.

Answer 1

The source data item is ONLY available during the binding events, and once that is is complete, then the binding source data goes out of scope, and is not available anymore. (you find that is is now empty after the binding events are done).

So, about the only thing you can do is say having in your listview is to include the PK id from the database, and use that. And for reasons of security, you don't need (or want) to include the PK data in the client side markup. So, you want to use the datakeys option.

Hence, say this markup:

                <asp:ListView ID="ListView1" runat="server"
                    DataKeyNames="ID">
                    <ItemTemplate>
                        <tr id="onerow" runat="server">
                            <td><asp:Label ID="FirstNameLabel" runat="server" Text='<%# Eval("FirstName") %>' /></td>
                            <td><asp:Label ID="LastNameLabel" runat="server" Text='<%# Eval("LastName") %>' /></td>
                            <td><asp:Label ID="CityLabel" runat="server" Text='<%# Eval("City") %>' /></td>
                            <td><asp:Label ID="Desciption" runat="server" Text='<%# Eval("Description") %>' /></td>
                            <td>
                                <asp:Button ID="cmdView" runat="server" Text="View Hotel" 
                                    OnClick="cmdView_Click" CssClass="btn" />
                            </td>
                        </tr>
                    </ItemTemplate>
                    <LayoutTemplate>
                        <table id="itemPlaceholderContainer" runat="server"
                            class="table table-hover">
                            <tr runat="server" style="">
                                <th runat="server">FirstName</th>
                                <th runat="server">LastName</th>
                                <th runat="server">City</th>
                                <th runat="server">Descripiton</th>
                                <th runat="server">View</th>
                            </tr>
                            <tr id="itemPlaceholder" runat="server">
                            </tr>
                        </table>
                    </LayoutTemplate>
                </asp:ListView>

And as noted, it is "unfortunate" that the data item source goes out of scope once data binding is complete. This means the data table (or class model) used to fill out the ListView is no longer available. So, you have to re-pull the data.

So, my button click code would thus become this:

  
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not IsPostBack Then
            LoadGrid()
        End If
    End Sub
 

    Sub LoadGrid()
        Dim strSQL As String =
            "SELECT * FROM tblHotelsA
                ORDER BY HotelName"
        ListView1.DataSource = MyRst(strSQL)
        ListView1.DataBind()
    End Sub

    Protected Sub cmdView_Click(sender As Object, e As EventArgs)
        Dim btn As Button = sender
        Dim lvRow As ListViewItem = btn.NamingContainer
        Dim intPK As Integer = ListView1.DataKeys(lvRow.DisplayIndex)("ID")
        Dim strSQL As String = $"SELECT * FROM tblHotelsA WHERE ID = {intPK}"
        Dim rstHotel As DataTable = MyRst(strSQL)
        With rstHotel.Rows(0)
            lblHotelName.Text = .Item("HotelName")
            lblCity.Text = .Item("City")
        End With
    End Sub

So, the data that drives the ListView (dataitem) is no longer available after the binding events are complete.

So, then your only choice is to pull data from the ListView row, or better is to get the PK of that row, and pull the data from the database. So, you can't pass or set the data item source with a command object, nor even "pass" the data item, since as I noted, it goes out of scope after binding events are completed. This also quite much means there is LITTLE reason to use the command object, and as above shows I just dropped into the ListVview a good old fashioned plain regular asp button, and you can pick up the current row with "naming container".