Binaryworld - Creating multi-steps input forms ... [ ASP.net -> General ]

In a typical user registration form, you may ask for quite a lot of data, such as the first and last name, full address, phone and fax numbers, e-mail address, newsletters subscriptions and other data for the site personalization. All this data shouldn't the asked in a single step, because a long list of input controls would probably discourage an user. It would be better to divide the form in a few steps, at least 2 or 3, so that the user perceives the process as simpler (even though they will ultimately fill in the same input controls anyway, of course). To do this, the typical ASP approach is to write separate pages, and pass the control from one to the following page. However, this is not very straighforward for the programmer, because he must find a way to pass to the following page all the user data typed into the current form, so that at the end of the process the last page will get all the inserted user data. Passing user data from a page to another is usually done with parameters in the querystring or with session variables, but in this case you can avoid these methods at all, and use a totally different approach to create multi-steps input forms. You can create two or three panels on the ASPX page, and show/hide them (by means of the Visible property) according to the current step index (that in increased/decreased by clicking two buttons). The Panel control acts like a container control, so you place the input controls of each steps inside the respective panel. Here's how you define the panels in the ASPx page:

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Note that only the first panel is visible by default, the other two are hidden. When the user presses the Next button, the first panel and its child controls will be made invisible, and the second panel will be shown with its child controls. The process is similar for the third step, where also a Finish button will be made visible. The great thing of this approach is that you don't need to have a separate page for each step, and so don't need to pass values from a page to another. Also consider that when a control has its server-side Visible property set to False its content is not sent to the client browser at all, so if you use this method you won't be sending the HTML code for the whole page, but just the HTML for the current step. Here's how you manage the whole process from the code-behind class:

Click here to copy the following block

Public Class InputForm : Inherits System.Web.UI.Page
  Protected FirstStep As System.Web.UI.WebControls.Panel
  Protected SecondStep As System.Web.UI.WebControls.Panel
  Protected ThirdStep As System.Web.UI.WebControls.Panel
  Protected ThirdStep As System.Web.UI.WebControls.Panel
  Protected Previous As System.Web.UI.WebControls.Button
  Protected Finish As System.Web.UI.WebControls.Button
  Protected Next As System.Web.UI.WebControls.Button

  Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
    If Not Me.IsPostBack Then
      ' the first time the page is loaded, set the current step index to 1
      ViewState("CurrentPage") = 1
    End If
  End Sub

  Private Sub Previous_Click(ByVal sender As Object, _
    ByVal e As System.EventArgs)
    ' Previous button clicked, decrease the step index by 1
    ShowPage(Integer.Parse(ViewState("CurrentPage").ToString()) - 1)
  End Sub

  Private Sub Next_Click(ByVal sender As Object, ByVal e As System.EventArgs)
    ' Next button clicked, increase the step index by 1
    ShowPage(Integer.Parse(ViewState("CurrentPage").ToString()) + 1)
  End Sub

  Private Sub ShowPage(ByVal page As Integer)
    ' save the current step index in the ViewState
    ViewState("CurrentPage") = page

    ' show/hide the panels and the Next/Previous/Finish buttons according
    ' to the current step index
    Select Case page
      Case 1
        Previous.Visible = False
        Next.Visible = True
        FirstStep.Visible = True
        SecondStep.Visible = False
        Exit Sub
      Case 2
        Previous.Visible = True
        Next.Visible = True
        Finish.Visible = False
        FirstStep.Visible = False
        SecondStep.Visible = True
        ThirdStep.Visible = False
        Exit Sub
      Case 3
        Next.Visible = False
        Previous.Visible = True
        Finish.Visible = True
        SecondStep.Visible = False
        ThirdStep.Visible = True
        Exit Sub
    End Select
  End Sub

  Private Sub Finish_Click(ByVal sender As Object, _
    ByVal e As System.EventArgs)
    ' When the Finish button is clicked, process the user input
  End Sub
End Class