Simple Question About Transferring Data.

**Dmyze** · Aug 13th, 2002, 11:44 AM

I am new to ASPX, I'm guessing this is just a simple question.

Ok so I have two ASPX WebForm pages.

The first page has a list box which a user may select items on.

The second page has a list box with only the items that were selected on the first page.

Very simple thing, in ASP I would create a form with a submit button and get the data that way. It doesn’t seem a <FORM> tag is proper in ASPX (it tells me "Per the active schema, the element 'FORM' cannot be nested within html")

So how are you supposed to transfer data from one page to another?

Maybe an array of a session variable?

**Patoooey** · Aug 13th, 2002, 12:42 PM

Transferring data from one page to another is possible but you should get into the mind-set of doing it all in one. Very simple example.

Code:

<%@ Page Language="C#" %>
<script runat="server">

    void Button1_Click(Object sender, EventArgs e) {
        ListBox1.Visible = false;
        ListBox2.Visible = true;
        ListBox2.Items.Clear();
        if (ListBox1.SelectedIndex > -1) {
            for (Int32 i=0;i<ListBox1.Items.Count;i++) {
                 if (ListBox1.Items[i].Selected)
                    ListBox2.Items.Add(ListBox1.Items[i].Text);
            }
    
        }
    }
    
    void Page_Load(Object sender, EventArgs e) {
        if (!Page.IsPostBack) {
            ListBox2.Visible = false;
        }
    }

</script>
<html>
<head>
</head>
<body>
    <form runat="server">
        <p>
            <asp:ListBox id="ListBox1" runat="server" Width="123px" Height="103px" SelectionMode="Multiple">
                <asp:ListItem Value="One">One</asp:ListItem>
                <asp:ListItem Value="Two">Two</asp:ListItem>
                <asp:ListItem Value="Three">Three</asp:ListItem>
                <asp:ListItem Value="Four">Four</asp:ListItem>
            </asp:ListBox>
            &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
            <asp:ListBox id="ListBox2" runat="server" Width="136px" Height="104px"></asp:ListBox>
        </p>
        <p>
            &nbsp;
        </p>
        <p>
            <asp:Button id="Button1" onclick="Button1_Click" runat="server" Text="Button"></asp:Button>
        </p>
        <!-- Insert content here -->
    </form>
</body>
</html>

**Dmyze** · Aug 13th, 2002, 01:50 PM

Thank you, but I still need to know how it's done.

The real issue is I have a report that I need to generate based on the information that is inputted. It involves multiple List boxes, combo boxes and text boxes, which a user fills out and then a printable report is generated. I do not believe that this is possible, at lest not practical to do on one page.

If someone provides me with an example of transferring list boxes from one page to another, I can figure out the rest.

**Patoooey** · Aug 13th, 2002, 02:15 PM

Originally posted by Dmyze
Thank you, but I do not believe that is what I asked for. Unless I am reading it wrong that looks like only one page.

A 5 second search on Google groups turned up numerous links to samples for passing data.

http://www.dotnetbips.com/displayarticle.aspx?id=79

The reason I didn't include it before is because, after 5 months of working with ASP.NET, that question has become a bore. Every ASP guy wants to transfer data from one page to another and I just don't see the point. It's easier to control on one page. You just plop a Panel or PlaceHolder in the HTML and fill it with whatever you want on every postback. Going from one page to another defeats the whole point of trying to get away from the spaghetti code of ASP apps.

I've seen multi-page wizards that were all one page. The only time I've used a seperate aspx page is to stream images. That works the same as b4.

It's not ASP. Free your mind.

http://www.aspnextgen.com/
http://www.asp.net/
http://www.4guysfromrolla.com/
http://aspalliance.com/

**Musician** · Aug 13th, 2002, 03:21 PM

This is the world of programming we are talking about isn't it? There is never one hard and fast way of doing things. I can straight away think of a good example of posting to another page. You have a search textbox on your main page. You make it a standard form who's action is GET so that the aspx page that displays search results gets the query from the querystring and the user can add the page to their favorites.
I'm very much into the "posting to self" mindset you talk about but there are numerous situations where you will want a user to be able to add a page to their favorites or send a link to a friend to a page that includes dynamic content. If it's dynamic then you need querystrings.

**Dmyze** · Aug 13th, 2002, 04:08 PM

I have over 80 reports that are going to use the same input screen. You want me to put all 80 reports onto one page?? I avoid Spaghetti Code by doing that?

I guess I'll figure out the server.transfer object, what a hassle for such a simple operation.

**Musician** · Aug 13th, 2002, 05:08 PM

Well dont despair. To answer your original question you can put a standard old form into your first page and get it to send to a new page. In the following example I use the get method so that the selected values will be in the querystring, a handy option for users if they want to save the page to their favorites.

<form id="Form1" method="get" action="newpage.aspx">
<SELECT name="options" multiple>
<OPTION value="opt1">Option1</OPTION>
<OPTION value="opt2">Option2</OPTION>
<OPTION value="opt3">Option3</OPTION>
<OPTION value="opt4">Option4</OPTION>
<OPTION value="opt5">Option5</OPTION>
</SELECT>
<input type="submit" value="Submit">
</form>

In newpage.aspx the code to get all the selected values would be as follows:

Dim coll As Collections.Specialized.NameValueCollection
Dim arrSelectedValues() as String
Dim arrKeys() as String
Dim x, y as integer

coll = Request.QueryString
arrKeys = coll.AllKeys
for x = 0 to arrKeys.GetUpperBound(0)
If arrKeys(x) = "options" then 'options is the listbox name here
arrSelectedValues = coll.GetValues(x)
End If
Next x
For y = 0 To arrSelectedValues.GetUpperBound(0)
Response.Write("Selected Value " & (y + 1) & ":" & arrSelectedValues(y) & "<br>")
Next

Now you have an array of the selected values (not the text values) of the listbox.

**Dmyze** · Aug 13th, 2002, 05:28 PM

(my hassle comment was towards the server.transfer object, not the forum..)

I don't want to do it the 'old way' if I wanted it done that way I would have never posted my question here. (not to mention I aleady devloped a cool WebForm for the start page that fills all kinds of fields with data for the user.)

I think the answer lies in the server.transfer object.

In my opinion if I was MS I would have made a extremely simple way to pass objects from one page to another, the objects are already running off the server I wouldn't think it would be hard to build a simple way to share objects.. But I'm not MS. Maybe server.transfer is simple, just all the articles I read on it say "somewhat complex but sophisticated method of passing values"

**Dmyze** · Aug 13th, 2002, 05:46 PM

Server.transfer was easy.

Code:

'In sending page:
  Public ReadOnly Property listStores() As ListBox
    Get
      Return lstStores
    End Get

  Private Sub cmdCreate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdCreate.Click

    Server.Transfer("stores.aspx")

  End Sub

'In recieving page:
  Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    Dim wf1 As dart._Default
    Dim lstItem As ListItem
    Dim lstTemp As ListBox
    'get reference to current handler instance
    wf1 = CType(Context.Handler, dart._Default)

    lstTemp = wf1.listStores


    For Each lstItem In lstTemp.Items
      lblList.Items.Add(lstItem)
    Next

  End Sub

**Musician** · Aug 13th, 2002, 06:29 PM

Funny how people refer to it as the old way.
<form runat="server">
renders as
<form action="self" method="post">
and the only difference in my "old" way is putting a get in for a post.
asp.net server controls are a simple way of rendering the same stuff as always except it includes events and stores state if you wish. Old way or new way your dealing with html and posted headers at the end of the day.

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