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Server tags cannot contain <% ... %> constructs RSS

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Last post Mar 19, 2009 09:29 AM by pjayasubramanyam

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MikeyBoyd

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33 Points

13 Posts

Server tags cannot contain <% ... %> constructs

Oct 08, 2006 09:26 PM|LINK

I've seen this posted a few times, but no satisfactory answer...any ideas would be greatly appreciated...

What I am trying to achieve is create a photo album type page with a main picture, then a bunch of thumbnails. When a thumbnail is selected, it will update the main picture.

I want the thumbnails to be generated automatically from a directory which is selected in a dropdown, hence the for next loop. The main picture will update if the image button is selected (via the

I get a "Server tags cannot contain <% ... %> constructs" error. I would like to know if there's a way around about this error as it has caused me other problems, but failing that what alternatives do I have.

Any replies greatfully received. The effect is rather cool, it will automatically create a photo album with none of the preparation normally required,
ie just point to your pics directory and everything else is created....big time saver. Will pass on the relevant aspx file if I get this resolved if anyone needs it.

Happy coding

Cheers

Mikey

'Code below

'********

<%
Dim files() As System.IO.FileInfo                           'Array of .jpg in a chosen directory
Dim strName As String                                        'This will be the filename xxxx.jpj
Dim url As String                                                 'url to update main picture
files = My.Computer.FileSystem.GetDirectoryInfo("C:\Inetpub\wwwroot\Guest\images\Pics\" & ddnList.Text).GetFiles()        'Populate files() with 'jpgs
For Each f As System.IO.FileInfo In files                             '****Create a new imagebutton (thumbnail) for each .jpg in directory
If Right$(f.Name, 4) = ".jpg" Then
strName = f.Name
url = "C:\Inetpub\wwwroot\Guest\images\Pics\" & ddnList.Text & "\" & ddnFiles.Text          '**Get url from directory from 2 x dropdowns
%>

<asp:ImageButton id= <%=strName %> runat="server"       '***Create the thumbnail               THIS IS THE OFFENDING LINE CAUSING ERROR
AlternateText = "Sort Ascending"                                       '***Not important
ImageUrl = <% =url %>                                                    '*Display image filename from dropdown
OnCommand = "ImageButton_Command"                           '*****Tells control to jump to sub below on selection
CommandName = "Sort"                                                     '***Not important
CommandArgument=<% =strName%>                                 'Parameter to pass to main picture via sub below
Height="41px" Width="55px"/>
<%
End If
Next
%>
'**********************

'**********************
Sub ImageButton_Command(ByVal sender As Object, ByVal e As CommandEventArgs)      'Enter this sub when imagebutton selected
hypPic.ImageUrl = "~/Guest/images/Pics/" & ddnList.Text & "/" & e.CommandArgument       '***This is the main picture
ddnFiles.Text = e.CommandArgument                                                                                'Updates the dropdown to reflect picture selected
End Sub
'**********************

Rick Rataycz...

Member

652 Points

140 Posts

Re: Server tags cannot contain <% ... %> constructs

Oct 09, 2006 12:41 AM|LINK

Wrap that in a DataList. Here's a web user control that can do what you want.

<img id="Image1" border="0" alt="Preview" />
<br /><br />


<div>
    <asp:DataList ID="DataList1" runat="server" RepeatColumns="2" Width="100%">
        <ItemTemplate>
            <div style="border: 1px outset;">
                <div>
                    <img id="<%# Eval("ID") %>" onclick="ShowImage(this.src);" src="<%# Eval("Image") %>" border="0" align="absmiddle" style="cursor: hand; width: 50px;" />
                </div>
                <div>
                    <%# Eval("Description") %>
                </div>
            </div>
        </ItemTemplate>
    </asp:DataList>
</div>


<script type="text/javascript">
<!--
    function ShowImage(i) {
        document.getElementById('Image1').src = i;
    }
//-->
</script>

And the code behind:

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

    Public Sub BindData()
        ' Sets the dataset to the folder of files.
        Me.DataList1.DataSource = GetDataset()
        Me.DataList1.DataBind()
    End Sub

    Public Function GetDataset() As System.Data.DataSet
        Dim Path As String = "/AVX2/eBook/PSP/img/"
        Dim F() As String = System.IO.Directory.GetFiles(Server.MapPath(Path), "*.jpg")
        Dim DS As New System.Data.DataSet("Results")
        Dim DT As Data.DataTable = DS.Tables.Add("Images")

        ' The string array to add rows
        Dim S(2) As String

        ' Add our columns to the datasource.
        DT.Columns.Add("Image")
        DT.Columns.Add("Description")
        DT.Columns.Add("ID")

        For A As Integer = 0 To F.Length - 1
            S(0) = Path + System.IO.Path.GetFileName(F(A))
            S(1) = System.IO.Path.GetFileNameWithoutExtension(F(A))
            S(2) = "Picture" + A.ToString
            DT.Rows.Add(S)
        Next

        Return DS
    End Function

Specializing in ASP.NET 2.0

Marked as answer by MikeyBoyd on Oct 10, 2006 11:16 AM

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mokeefe

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2098 Posts

Re: Server tags cannot contain <% ... %> constructs

Oct 09, 2006 01:33 AM|LINK

ASP.Net 2.0

Adding the images from code

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="ImagesList.aspx.vb" Inherits="ImagesList" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >

<head runat="server">

    <title>Untitled Page</title>

</head>

<body>

    <form id="form1" runat="server">

    <div>

    <asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>

    </div>

    </form>

</body>

</html>

Partial Class ImagesList

    Inherits System.Web.UI.Page

    Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreInit

        ' ASP.Net 2.0

        ' NOTE Page has placeholder with ID PlaceHolder1

        ' Create the dynamic controls

        ' using app root for sample

        Dim dirInf As New IO.DirectoryInfo(Server.MapPath("/"))

        ' filter on vb files - you would use jpg or a combination of alternates such as *.bmp

        Dim fls() As IO.FileInfo = dirInf.GetFiles("*.vb")

        ' this will output the images in flow layout, if you want more of a straight list

        ' you would add each image to a parent container that had width assinged to an

        ' appropriate size to wrap the images

        For Each fl As IO.FileInfo In fls

            ' Build an aspx image and add to placeholder

            ' NOTE Using an image button to handle click event!

            Dim img As New ImageButton

            ' I'm setting alternate text as I won't assignt eh imageurl

            img.AlternateText = fl.FullName

            ' the other image properties

            '.......

            AddHandler img.Click, AddressOf Me.ImageButton_Click

            ' add to placeholder

            Me.PlaceHolder1.Controls.Add(img)

        Next

        ' As for server tags in a server control - thats a negative.

    End Sub

    Protected Sub ImageButton_Click(ByVal sender As Object, ByVal e As System.Web.UI.ImageClickEventArgs)

        Dim imgBtn As ImageButton = sender

        imgBtn.AlternateText = "Been Cliked " & imgBtn.AlternateText

    End Sub

End Class

Rgds,

Martin.

Rgds,
Martin.

For the benefit of all users please mark any post answers as appropriate.
- Marked as answer by MikeyBoyd on Oct 10, 2006 11:17 AM
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MikeyBoyd

Member

33 Points

13 Posts

Re: Server tags cannot contain <% ... %> constructs

Oct 09, 2006 12:08 PM|LINK

OMG...you guys are stars. I will try those very elegant pieces of work...

I did almost get a solution using purely code behind (preferred by pro's but I'm a humble hobbyist newbie)..however the 'OnCommand' doesn't appear to be available programmatically? OnClientClick is however.

Thanks once again.

Mikey

files = My.Computer.FileSystem.GetDirectoryInfo("C:\Inetpub\wwwroot\Guest\images\Pics\" & ddnList.Text).GetFiles()
For Each f As System.IO.FileInfo In files
If Right$(f.Name, 4) = ".jpg" Then
Dim myImage As ImageButton = New ImageButton()
Dim j As Integer
j = j + 1
'Set the label's Text and ID properties.
myImage.ID = CStr(j)
myImage.ImageUrl = "~\Guest\images\Pics\" & ddnList.Text & "\" & f.Name
myImage.Height = 40
myImage.Width = 50
myImage.ToolTip = f.Name
myImage.OnCommand = "ImageButton_Command" 'Not available programatically??
myImage.CommandName = "NA"
myImage.CommandArgument = f.Name
myImage.AlternateText = f.Name
PlaceHolder1.Controls.Add(myImage)
Dim spacer As LiteralControl = New LiteralControl(" ") 'Add a spacer in the form of a single space
PlaceHolder1.Controls.Add(spacer)
End If
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MikeyBoyd

Member

33 Points

13 Posts

Re: Server tags cannot contain <% ... %> constructs

Oct 09, 2006 02:52 PM|LINK

Got it, thanks for the help. For those of you interested, this is the full code for a basic but effective Phot Gallery, key features I was looking for were:-

- Automatically pull all files within a directory and create a main image with thumbnails for all images, select thumnail to update main image
- Dropdown to select directory and image

Only preparation I would suggest are
1. Resize images (MS Powertoys works a treat)
2. Keep the number of images in each directory to a minimum since it loads all images in all their glory, so may be sloow

Next challenge is to add
1. Slideshow (update to next image every 5 secs or so)
2. Text boxes for resizing to other defaults (current is good for 1024x768 and images are 640x480)
2. See if I can find a way to only load the main pic on each post back (either frames or may require Atlas/Ajax) - any tips here greatfully received.

Here it is

'******************

<%@ Page Language="VB" MasterPageFile="~/MasterPage.master" Title="Untitled Page" %>

<script runat="server">

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

Dim Di As New System.IO.DirectoryInfo("C:\Inetpub\wwwroot\Guest\images\Pics")

Dim files() As System.IO.FileInfo

Dim SubDir() As System.IO.DirectoryInfo = Di.GetDirectories()

If IsPostBack = False Then

For Each sdi As System.IO.DirectoryInfo In SubDir

Me.ddnList.Items.Add(sdi.Name)

Next

files = My.Computer.FileSystem.GetDirectoryInfo("C:\Inetpub\wwwroot\Guest\images\Pics\" & ddnList.Text).GetFiles()

For Each f As System.IO.FileInfo In files

If Right$(f.Name, 4) = ".jpg" Then

Me.ddnFiles.Items.Add(f.Name)

End If

Next

End If

files = My.Computer.FileSystem.GetDirectoryInfo("C:\Inetpub\wwwroot\Guest\images\Pics\" & ddnList.Text).GetFiles()

For Each f As System.IO.FileInfo In files

If Right$(f.Name, 4) = ".jpg" Then

Dim myImage As ImageButton = New ImageButton()

Dim j As Integer

j = j + 1

'Set the label's Text and ID properties.

myImage.ID = CStr(j)

myImage.ImageUrl = "~\Guest\images\Pics\" & ddnList.Text & "\" & f.Name

myImage.Height = 40

myImage.Width = 50

myImage.ToolTip = f.Name

'myImage.OnCommand = "ImageButton_Command"

myImage.CommandName = "NA"

myImage.CommandArgument = f.Name

myImage.AlternateText = f.Name

AddHandler myImage.Command, AddressOf Me.ImageButton_Command

PlaceHolder1.Controls.Add(myImage)

'Add a spacer in the form of an HTML <BR> element

Dim spacer As LiteralControl = New LiteralControl(" ")

PlaceHolder1.Controls.Add(spacer)

End If

Next

End Sub

Protected Sub ddnFiles_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)

imgMain.ImageUrl = "~/Guest/images/Pics/" & ddnList.Text & "/" & ddnFiles.Text

' hypPic.NavigateUrl = "~/Guest/Slideshows/" & ddnList.Text & "/" & ddnFiles.Text

End Sub

Protected Sub ddnList_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)

Dim files() As System.IO.FileInfo

ddnFiles.Items.Clear()

files = My.Computer.FileSystem.GetDirectoryInfo("C:\Inetpub\wwwroot\Guest\images\Pics\" & ddnList.Text).GetFiles()

For Each f As System.IO.FileInfo In files

If Right$(f.Name, 4) = ".jpg" Then

Me.ddnFiles.Items.Add(f.Name)

End If

Next

imgMain.ImageUrl = "~/Guest/images/Pics/" & ddnList.Text & "/" & ddnFiles.Text

End Sub

Sub ImageButton_Command(ByVal sender As Object, ByVal e As CommandEventArgs)

imgMain.ImageUrl = "~/Guest/images/Pics/" & ddnList.Text & "/" & e.CommandArgument

'imgMain.Text = e.CommandArgument

ddnFiles.Text = e.CommandArgument

End Sub

</script>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">

<script language="javascript" type="text/javascript">



</script>

<br />

<asp:DropDownList ID="ddnList" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddnList_SelectedIndexChanged">

</asp:DropDownList> <asp:DropDownList ID="ddnFiles" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddnFiles_SelectedIndexChanged">

</asp:DropDownList><div style="text-align: center">

 <br />

<table>

<tr>

<td style="width: 89px">

<asp:ImageButton ID="imgMain" runat="server" Height="400px" ImageUrl="~/Guest/images/Pics/Bell Island/Bell Island (1).jpg" Width="550px" /></td>

</tr>

</table>

<br />

</div>

<hr />

 <asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>

</asp:Content>

Image Viewer Server Tags
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mokeefe

Star

10850 Points

2098 Posts

Re: Server tags cannot contain <% ... %> constructs

Oct 10, 2006 03:14 AM|LINK

Glad to be of help.

You might wish to tick both answer from Rick and myself.

You might also not e that both examples show how to filter the files based on file extension which would negate the later review on each file.

happy coding.

Martin.

- Some other stuff you might be interested in.

        ' dynamically add a table

        Dim Table As New HtmlControls.HtmlTable

        ' build a row

        Dim rw As New HtmlControls.HtmlTableRow

        Dim cell As New HtmlControls.HtmlTableCell

        rw.Controls.Add(cell)

        'Add image button to cell

        Dim imageBtn As New ImageButton()

        imageBtn.AlternateText = "No Image Set"

        cell.Controls.Add(imageBtn)

        ' add row to table

        Table.Controls.Add(rw)

        ' add table to placeholder

        PlaceHolder1.Controls.Add(Table)

        'add placeholder to page

        ' You would add to your contentplaceholder not the form!

        Me.form1.Controls.Add(PlaceHolder1)

        ' Using generic HTML Controls

        'add a div

        Dim dv As New HtmlControls.HtmlGenericControl("div")

        dv.InnerText = "I am dynamically added"

        ' put in cell beside image

        cell.Controls.Add(dv)

        ' end add *****************

Rgds,
Martin.

For the benefit of all users please mark any post answers as appropriate.
- Marked as answer by MikeyBoyd on Oct 10, 2006 11:17 AM
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volking

Member

44 Points

22 Posts

Re: Server tags cannot contain <% ... %> constructs

Oct 17, 2007 02:26 PM|LINK

--------------------------
The Problem
--------------------------

Error is:
Server tags cannot contain <% ... %> constructs

Problem deals with the order in which .NET does things.

In ASP, we used to be able to do this ...
    <a href="/help/<%=MyHelpPage%>.asp">hyperlink</a>
and ...
    <%=MyHelpPage%> ... got substituted with the string value.

So I tried something similar with ASP hyperlink control ...
<asp:HyperLink NavigateUrl="~/help/<%=MyHelpPage%>.aspx" ID="HyperLink1" runat="server">hyperlink</asp:HyperLink>

Above is WRONGLY translated to HTML like this ...
href="~/help/<%=MyHelpPage%>/.aspx"

and every thing else I tried ended with: Server tags cannot contain <% ... %> constructs
Bottom line ... it don't work!

So ... how to accomplish similar funcationality in ASP.NET

---------------------------
The Solution (in VB)
---------------------------

Code in markup ...

    <asp:HyperLink NavigateUrl='<%#mHelpPageURL & "bookmark" %>' ID="HyperLink1" runat="server">
    <img src="images/myicon.GIF" border="0" />
    </asp:HyperLink>

Code in Code Behind

    Partial Class mywebpage
        Public mHelpPageURL As String = "~/help/use1_help.aspx#"
        Protected Sub Page_Load(...)
            Me.Page.DataBind()
        End Sub
    End Class

Because of the order in which ASP.NET processes things, the solution needs DATA BINDING to work. The # sign in the asp <%...%> tells the compiler that this is a DataBound value. The exact syntax between the <% and %> depends on the language being used (VB or C#). In the code behind, notice Page.DataBind(). That's the call which does the work.

Frederick
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mokeefe

Star

10850 Points

2098 Posts

Re: Server tags cannot contain <% ... %> constructs

Oct 18, 2007 01:26 PM|LINK

Hi Fred,

Why would you use databinding for a single ASP Control not contained in an ITemplate? You would be better assigning the Asp Hyperlink controls NavigateUrl property in the code as databinding incurs more overhead.

Rgds,
Martin.

For the benefit of all users please mark any post answers as appropriate.
- Reply
volking

Member

44 Points

22 Posts

Re: Server tags cannot contain <% ... %> constructs

Oct 19, 2007 04:22 AM|LINK

Why? Because I'm supporting a 25,000 line ASP application which we're converting (piece-meal) to ASP.NET 2.0 and most pages in the original website have 10-20 of these type embedded substitutions. (smile) Otherwise, I wouldn't (grin) You know the drill, "Just Make It Work!".

Frederick
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wufpakbob

Member

2 Points

1 Post

Re: Server tags cannot contain <% ... %> constructs

Nov 28, 2007 07:50 PM|LINK

Rick, Thank you for the above code! It took me hours to finally find a good example, because no matter what I do, my javascript will not recognize the "Image1" control.

I really don't think I had to change anything from your code example except the Path in the code behind.

The thumbnails display when the page loads, but the main image does not. When you click a thumbnail, I get to the first alert box with it displaying a valid URL to display the image. However the next line does not work. I get the following error message when I click on the yellow exclamation in the left corner of the browser.

Line: 165

Char: 5

Error: 'document.getElementById(...)' is null or not an object

Code: 0

Url: http://localhost:3318/paid2pixelclick/Default3.aspx

Below is the code as I just ran it:

****************************************************************************
<%@ Page Language="VB" MasterPageFile="~/MasterPage.master" AutoEventWireup="false" CodeFile="Default3.aspx.vb" Inherits="Default3" title="Untitled Page" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">

<img src="" runat="server" id="Image1" alt="Preview" />
<br /><br />

<div>

<asp:DataList ID="DataList1" runat="server" RepeatColumns="3" Width="100%">

<ItemTemplate>

<div style="border: 1px outset;">

<div>

<img alt="" id="<%# Eval("ID") %>" onclick="ShowImage(this.src);" src="<%# Eval("Image") %>" style="border:0; vertical-align:middle; cursor: hand; width: 50px;" />

</div>

<div>
<%# Eval("Description") %>
</div>

</div>

</ItemTemplate>
</asp:DataList>
</div>

<script type="text/javascript">


</script>
</asp:Content>

***********************************************************

************* Code Behind Below

**********************************************************
Partial Class Default3Inherits System.Web.UI.Page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

If Not Page.IsPostBack Then

BindData()

End If

End Sub
Public Sub BindData()
' Sets the dataset to the folder of files.
Me.DataList1.DataSource = GetDataset()
Me.DataList1.DataBind()

End Sub
Public Function GetDataset() As System.Data.DataSet
Dim Path As String = "SecUploadedImages/"
Dim F() As String = System.IO.Directory.GetFiles(Server.MapPath(Path), "*.jpg")
Dim DS As New System.Data.DataSet("Results")
Dim DT As Data.DataTable = DS.Tables.Add("Images")
' The string array to add rows

Dim S(2) As String

' Add our columns to the datasource.
DT.Columns.Add("Image")
DT.Columns.Add("Description")
DT.Columns.Add("ID")For A As Integer = 0 To F.Length - 1
S(0) = Path + System.IO.Path.GetFileName(F(A))

S(1) = System.IO.Path.GetFileNameWithoutExtension(F(A))
S(2) = "Picture" + A.ToString
DT.Rows.Add(S)

Next
Return DSEnd Function

End Class

******************************************************************

Thanks in advance for your help,

Bob

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Server tags cannot contain <% ... %> constructs

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MikeyBoyd

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volking

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