How to dynamically generate textbox and collect da

I will appreciate answers in VB or C#

we use a database to create Data Collection forms with dynamic items

I used this code to generate labels and textboxes from a table in database (when the user hits the button "load CRF")

 Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim CRFgrid As New GridView
    CRFgrid.DataSource = CRFds
    CRFgrid.DataBind()

    Dim ItemCount As Integer = CRFgrid.Rows.Count
            Session("Itemcount") = CRFgrid.Rows.Count

    For I = 0 To (ItemCount - 1)
        Dim itemname As String = CRFgrid.Rows(0 + I).Cells(1).Text.ToString
        Session("Item") = "Item" + (I + 1).ToString
        Dim ItemNamelabel As New Label
        Dim ItemNameBox As New TextBox

        ItemNamelabel.ID = "L" + (I + 1).ToString
        Session("FU" + I.ToString) = ItemNamelabel.ID.ToString
        ItemNameBox.ID = "T" + (I + 1).ToString

        ItemNamelabel.Text = "<br />" + (Session("Item").ToString) + " " + itemname + " " + "<br />"

        Me.Form.Controls.Add(ItemNamelabel)
        Me.Form.Controls.Add(ItemNameBox)



    Next
End Sub

when the data collection form is loaded, the page looks like this

and the "view page source" shows

    <!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><title>

 </title></head>
<body>
<form method="post" action="Default.aspx" id="form1">
<div class="aspNetHidden">
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE"     value="/wEPDwUKLTI0NTA5MDI3NGRkUb8sl0uZpLbvUN/GSmHgjYxS9xqGR7rmcMBR3Ufhz4w=" />
</div>

<input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" value="/wEWCQLf7PXOCQKM54rGBgK7q7GGCALF9vKRBQLs7+btDALs7+LtDALs797tDALs79rtDALs79btDDHrb+Vhkcph8brtCJP9//5IH57FFoImey2PApARP+k1" />

<input type="submit" name="Button1" value="LoadCRF" id="Button1" style="width:85px;" />
<br />
<br />
<input type="submit" name="Button2" value="InsertData" id="Button2" style="width:85px;" />
<br />
<br />

MRN
<input name="MRNtxt" type="text" id="MRNtxt" />
<br />
<br />
<span id="L1"><br />Item1 Diagnosis <br /></span><input name="T1" type="text" id="T1" /><span id="L2"><br />Item2 Treatment Protocol <br /></span><input name="T2" type="text" id="T2" /><span id="L3"><br />Item3 Initial CSF <br /></span><input name="T3" type="text" id="T3" /><span id="L4"><br />Item4 Location <br /></span><input name="T4" type="text" id="T4" /><span id="L5"><br />Item5 Consultant <br /></span><input name="T5" type="text" id="T5" /></form>

once the user fills the form and click insert, i want to save entered text into a other tabel in the database using this code. it does not work. can u tell me where my mistake is?

Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click


    Dim mydb As New OleDbConnection
    mydb =
    New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source= |datadirectory|openclinica.mdb;Persist Security Info=True")
    mydb.Open()
    Dim Y As Integer = Session("Itemcount")
    For M = 1 To Y

        Session("FUt") = "L" + M.ToString
        Session("FUDt") = "T" + M.ToString

        Dim sqlstring = "INSERT INTO [Followup] ([MRN], [FU], [FUData]) VALUES (@MRNtxt, @" + Session("FUt") + ", @" + Session("FUDt") + ");"
        Dim mydbcommand As New OleDbCommand(sqlstring, mydb)
        mydbcommand.Parameters.Add("@MRNtxt", OleDbType.VarChar).Value = MRNtxt.Text
        mydbcommand.Parameters.Add("@" + Session("FUt"), OleDbType.VarChar).Value = Session("FUt").Text
        mydbcommand.Parameters.Add("@" + Session("FUDt"), OleDbType.VarChar).Value = Session("FUDt").Text
        mydbcommand.ExecuteNonQuery()

    Next

    mydb.Close()
End Sub

the error message looks like this when i click "insert"

回答1:

You need to retrieve the actual controls that are created in button1_click instead of their ids that you store in the session state.

However, because these controls are dynamically created at runtime, your code will become substantially more complex because you will have to add all of the controls to the page every time Page Init is called. See the following articles for additional information:

ASP.NET Page Life Cycle Overview

View State and Dynamically Added Controls

Dynamic Web Controls, Postbacks, and View State

Based on the complexity that this introduces, I would suggest a more straightforward approach where you have a number of labels and text boxes already on the page, but hidden by CSS attributes (display: none; visibility: hidden).

An even better approach is to use a grid control, which is ideally suited to this kind of behavior. There are plenty of examples here:

Table of Contents: GridView Examples for ASP.NET 2.0

回答2:

Please Check this article

Creating Dynamic User Friendly Web-Based Data Collection Forms

回答3:

It is your ... = Session("FUt").Text and ... = Session("FUDt").Text.

These are strings, and the .Text is attempting to call a property that does not exist.

回答4:

Where is Session defined? Have you checked access level of the Text property (it needs to be public otherwise the exception you are getting will be thrown)?