Get text from dynamically created textbox in asp.net

c# asp.net .net dynamic controls

22,755

Solution 1

You're right, it's all about the page lifecycle. Dynamically created controls must be re-created at the Page_Init stage, in order to exist before the viewstate binding stage. This means that will have to somehow (using the Session, maybe) store how many textboxes you have created on the previous processing to recreate them. Remind to use the same ID and to add them to your control tree (a repeater or something else that you're using).

UPDATE

Let me give you a suggestion: 1. Declare a class attribute of type List<TextBox> (let's call it CreatedTextBoxes)

Declare a method that receives whatever it needs to create the textboxes. This method must not read anything outside of it's scope. It will simply receive some args, create the textboxes and add them to another control (such as a Repeater). Add each textbox created to CreatedTextBoxes
At the dropdown change event, read the option, save it to the Session and call this method
At Page_Init, verify that object at the Session. If it's null or empty, don't do anything. If it has a value, call that same method, passing the same args
When you need to retrieve that from the dynamically created textboxes, use CreatedTextBoxes and not FindControls()

Solution 2

You add TextBox controls to templateFormPlaceholder.Controls but use form1.FindControl to find them. FindControl method will find a control only if the control is directly contained by the specified container - from http://msdn.microsoft.com/en-us/library/486wc64h.aspx. Try calling templateFormPlaceholder.FindControl instead.

Solution 3

Create Dynamic TextBoxes and add it to a asp panel so that you can access it easily.

Here is the ASP.NET design elements.

<div class="form-group">
<asp:Panel ID="panel" runat="server" CssClass="form-group">

</asp:Panel>
</div>

C# Code to generate Dynamic textboxes

 protected void create_dynamic_text(object sender, EventArgs e)
{
    int num = 5; // you can give the number here
    for (int i = 0; i < num;i++ )
    {
        TextBox tb = new TextBox();
        tb.ID = "txt_box_name" + i.ToString();
        tb.CssClass = "add classes if you need";
        tb.Width = 400; //Manage width and height 
        panel.Controls.Add(tb); //panel is my ASP.Panel object. Look above for the design code of ASP panel
    }
}

C# Code to Take Values

 protected void reade_values(object sender, EventArgs e)
{
   int num=5; // your count goes here
    TextBox tb = new TextBox();
        for (int i = 0; i < num; i++)
        {
           tb=(TextBox)panel.FindControl("txt_box_name"+i.ToString());
           string value = tb.Text; //You have the data now
        }
    }
}

22,755

Author by

mElling

Updated on November 17, 2020

Comments

mElling over 3 years

I've been banging my head against this all morning, so hopefully I can get some help. Essentially I'm having issues getting values from some textbox controls I'm creating dynamically in .net 4.

Here's the desired flow of the application.

1). User selects a html document from a dropdown menu that is a template for a letter. This html document has tags of the format $VARIABLENAME$ that will be replaced with the correct values.

2). The program runs though the template and pulls out all strings of the format $STRING$ and stores them in a list.

3). For each entry in this list, the program generates an asp:label and an asp:textbox with a unique ID based on the original $VARIABLENAME$ field.

4). User enters replacement values, and hits submit.

5). Program replaces all $STRING$'s with the replacement values and outputs the result.

Everything works well up to the point where I need to get values from the text boxes. I'm quite sure it's an issue with the page lifecycle, but because the textboxes are not being generated until the use selects the desired template from the dropdown, I'm not sure how to make them persist through postbacks so I can reference them.

Am I going about this all wrong? How do I access the text fields created from a dropdown event after a postback froma submitbutton event occurs?

EDIT: Here's the most of the relevant code.

protected void createTextBoxes(List<string> results)
    {
        if (results != null)
        {
            foreach (string result in results)
            {
                string formattedResult = result.Substring(1, result.Length - 2);
                formattedResult = formattedResult.ToLower();
                formattedResult = char.ToUpper(formattedResult[0]) + formattedResult.Substring(1);


                var label = new Label();
                label.ID = formattedResult;
                label.Text = formattedResult + ": ";
                templateFormPlaceholder.Controls.Add(label);

                var textBox = new TextBox();
                textBox.ID = result;
                templateFormPlaceholder.Controls.Add(textBox);
                templateFormPlaceholder.Controls.Add(new LiteralControl("<br />"));

                previewBtn.Visible = true;
            }
        }
    }

protected void templateDD_SelectedIndexChanged(object sender, EventArgs e)
    {
        var templatePath = "";
        if (templateDD.SelectedIndex == 0)
        {
            previewBtn.Visible = false;
        }

        if (templateDD.SelectedIndex == 1)
        {
            templatePath = employeePath;
        }
        else if (templateDD.SelectedIndex == 2)
        {
            templatePath = managerPath;
        }
        List<string> regMatches = FindMatches(templatePath);
        Session["regMatches"] = regMatches;
        createTextBoxes(regMatches);
    }

protected void Page_Init(object sender, EventArgs e)
    {
        if (Session["regMatches"] != null)
        {
            createTextBoxes((List<string>)Session["regMatches"]);
        }
    }

Later on, I'm trying to add the values from these textboxes to a dictionary. Parameters is the name of the dictionary. The key field is the $STRING$, result is what the user entered in the text box.

   protected void previewBtn_Click(object sender, EventArgs e)
    {
        List<string> matchResults = (List<string>)Session["regMatches"];
        Dictionary<string, string> parameters = new Dictionary<string, string>();
        foreach (string result in matchResults)
        {
            TextBox tb = (TextBox)templateFormPlaceholder.FindControl(result);
            parameters.Add(result, tb.Text);
        }

        var template = ReplaceKeys(parameters);
        outputLBL.Text = template;

Here's the .aspx code.

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="offerLetter.aspx.cs"     Inherits="templateRegexTesting.offerLetter" %>

<!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></title>
</head>
<body>
<form id="form1" runat="server">
<div>
    <p>
        Which template would you like to use?
    </p>
    <asp:DropDownList ID="templateDD" runat="server" OnSelectedIndexChanged="templateDD_SelectedIndexChanged"
        AutoPostBack="true">
        <asp:ListItem></asp:ListItem>
        <asp:ListItem Value="1">Employee</asp:ListItem>
        <asp:ListItem Value="2">Manager</asp:ListItem>
    </asp:DropDownList>
    <br />
    <asp:PlaceHolder ID="templateFormPlaceholder" runat="server" />
    <div>
        <asp:Button ID="previewBtn" runat="server" Text="Preview" Visible="false" OnClick="previewBtn_Click" />
    </div>
    <div>
        <asp:Label ID="outputLBL" runat="server"></asp:Label>
    </div>
    <br />
</div>
</form>
</body>
</html>

EDIT: I put this in a comment when I figured it out, but I figured I should move it into the question so it is more visible:

Thought I should update this. I feel like a bit of an idiot, but I did manage to get this working. Basically I was assigning the controls an ID equal to the replacement tokens (So ID="$FIRSTNAME$" for example). It didn't even dawn on me that the $'s would cause any issues. When I just changed to the format ID="Firstname" it works perfectly. Thank you for all of the help!