¿ When To Use "e.Item.FindControl()" ? 1

[MCuthill]

Hi Everyone,

It was recommended I post this in the ASP forum instead of the Visual Basic forum.

Perhaps the solution to this is more simple than I am making it out to be. I am trying to get the contents of a field within a DataList to assign to a variable, and thought I could use e.Item.FindControl(). After several attempts and variations on the code I still get a Null return from fields I know to be populated.

Can I get the text contained from a field for a particular Item using this method, or do I need to use an SQLReader to obtain the information?

I am using Visual Basic Code Behind on ASP.NET pages (using Visual Studio 2005)

Thanks,


Mike
"It Seems All My Problems Exist Between Keyboard and Chair"

 

[ca8msm]

Can you post the aspx portion that contains your DataList?


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[jbenson001]

What event are you trying to do this code in?

 

[MCuthill]

I am coding the event in

Private Sub SearchResults_ItemCommand(ByVal source As Object, ByVal e As DataListCommandEventArgs) Handles SearchResults.ItemCommand

Here is the ASPX for the DataList.

 <asp:DataList ID="SearchResults" runat="server" DataSourceID="SqlDataSource1"
        Font-Bold="True" Style="color: white" Width="536px" DataKeyField="ResourceID">
        <ItemTemplate>
            <asp:Label ID="ResourceIDLabel" runat="server" Text='<%# Eval("ResourceID") %>' Visible="False"></asp:Label>&nbsp;
            <asp:Label ID="ActivityTypeIDLabel" runat="server" Text='<%# Eval("ActivityTypeID") %>'
                Visible="False"></asp:Label><br />
            <asp:Label ID="TitleLabel" runat="server" Font-Bold="True" Font-Italic="True" Font-Size="14pt"
                Text='<%# Eval("Title") %>'></asp:Label><br />
            by:
            <asp:Label ID="AuthorLabel" runat="server" Text='<%# Eval("Author") %>'></asp:Label><br />
            <br />
            Description:
            <asp:Label ID="DescriptionLabel" runat="server" Font-Bold="False" Font-Italic="False"
                Text='<%# Eval("Description") %>'></asp:Label><br />
            <br />
            Format:
            <asp:Label ID="FormatLabel" runat="server" Font-Bold="False" Text='<%# Eval("Format") %>'></asp:Label><br />
            Date Signed Out:
            <asp:Label ID="DateSignedOutLabel" runat="server" Font-Bold="False" Text='<%# Eval("DateSignedOut", "{0:d}") %>'></asp:Label><br />
            Loan Period:
            <asp:Label ID="LoanPeriodLabel" runat="server" Font-Bold="False" Text='<%# Eval("LoanPeriod") %>'></asp:Label><br />
            Signed Out To:
            <asp:Label ID="SignedOutToLabel" runat="server" Font-Bold="False" Text='<%# Eval("SignedOutTo") %>'></asp:Label><br />
            <br />
            <asp:Button ID="cmd_SignOut" runat="server" Text="Sign Out This Resource" Width="240px" commandname="SignOut" Visible='<%# Container.DataItem("ResourceID") %>' /><br />
            &nbsp;
        </ItemTemplate>
        <ItemStyle BorderStyle="Solid" BorderWidth="1px" />
    </asp:DataList>

Mike
"It Seems All My Problems Exist Between Keyboard and Chair"

 

[jbenson001]

ok.. so where is the code you are placing in the event that is causing the error or not working

 

[MCuthill]

I found examples of using "Dim TitleLbl As Label = CType(e.Item.FindControl("Title"), Label)" on the web, MSDN I think. In my situation they are always returning NULL, I also have tried using e.item.parent.findcontrol("title").

Private Sub SearchResults_ItemCommand(ByVal source As Object, ByVal e As DataListCommandEventArgs) Handles SearchResults.ItemCommand
        Dim primaryKey As Integer = e.Item.ItemIndex
        'Pull Contents of the Resources Fields
        Dim TitleLbl As Label = CType(e.Item.FindControl("Title"), Label)
        Dim AuthorLbl As Label = CType(e.Item.FindControl("Author"), Label)
        Dim FormatLbl As Label = CType(e.Item.FindControl("Format"), Label)
        'Cast Labels to String Values
        Dim Title As String = Val(TitleLbl)
        Dim Author As String = Val(AuthorLbl)
        Dim Format As String = Val(FormatLbl)

        MsgBox("Object Selected: " & primaryKey & ", " & Title, MsgBoxStyle.OkOnly, "Object Selected")
    End Sub

Mike
"It Seems All My Problems Exist Between Keyboard and Chair"

 

[jbenson001]

i am surprised you arenot getting "object not set to instance of an object" error
You are trying to find the dataset columns, not the controls.

Change:

  Dim TitleLbl As Label = CType(e.Item.FindControl("Title"), Label)
        Dim AuthorLbl As Label = CType(e.Item.FindControl("Author"), Label)
        Dim FormatLbl As Label = CType(e.Item.FindControl("Format"), Label)

To:

  Dim TitleLbl As Label = CType(e.Item.FindControl("[b]TitleLabel[/b]"), Label)
        Dim AuthorLbl As Label = CType(e.Item.FindControl("[b]AuthorLabel[/b]"), Label)
        Dim FormatLbl As Label = CType(e.Item.FindControl("[b]FormatLabel[/b]"), Label)

Jim

 

[MCuthill]

Thanks Jim,

I had to change the code a little to get the value as a string. The MsgBox is just used to test my code, and all values show.

Below is the working code.

Private Sub SearchResults_ItemCommand(ByVal source As Object, ByVal e As DataListCommandEventArgs) Handles SearchResults.ItemCommand
        Dim primaryKey As Integer = e.Item.ItemIndex
        'Pull Contents of the Resources Fields
        Dim Title As String = CType(e.Item.FindControl("TitleLabel"), Label).Text
        Dim Author As String = CType(e.Item.FindControl("AuthorLabel"), Label).Text
        Dim Format As String = CType(e.Item.FindControl("FormatLabel"), Label).Text

        MsgBox("Object Selected: " & primaryKey & ", " & Title & ", " & Author & ", " & Format, MsgBoxStyle.OkOnly, "Object Selected")
    End Sub

Mike
"It Seems All My Problems Exist Between Keyboard and Chair"

 

[jbenson001]

Glad it is working and glad to help.

Just remember that a messagbox only shows on the server, NOT the client, so your code wouldn't work if your PC was not the server. Just a little side note for you to consider.

Jim