Develop Reference

Saving Data to the Database from Dynamically created asp.net textboxes

First off, I've seen a ton of posts for this same question but what I don't understand is when somebody gives an answer about "recreating the controls to page init" or ... I have the code to dynamically CREATE the text boxes but I'm not sure what else I need to add. I don't completely understand the page life cycle of asp.net web apps. I've googled this and I dont know if I'm incompetent or if all of the answers given are for people with more understanding than me.
PLEASE provide an example of what you explain.
Basically The user enteres a # into the textbox for how many "favorite books" they want to save into the database, he/she clicks the generate button.
that # of rows will populate with two textboxes, one for title and one for author. Then I would have a button they click that would save the textbox values into the database.
I know it's a simple exercise but I'm new to asp.net and it's just an exercise I came up by myself that I'm trying to learn. I'm open to new design for this but the one thing I prefer not to do is create the textboxes statically. Thanks! <3
this is the asp.net code I have
<form id="form1" runat="server">
<div>
How many favorite books do you have ?
<asp:TextBox ID="TextBox1" runat="server" Width="50px"></asp:TextBox>
<br />
<asp:Button ID="btnBookQty" runat="server" Text="GenerateBooks" OnClick="btnBookQty_Click" />
<br />
<br />
<asp:Panel ID="pnlBooks" runat="server"></asp:Panel>
</div>
</form>
and my c# code is
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class databasetest_panels_favBookWebsite : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnBookQty_Click(object sender, EventArgs e)
{
int count = Convert.ToInt32(TextBox1.Text);
for (int i = 1; i <= count; i++)
{
TextBox tb = new TextBox();
TextBox tb2 = new TextBox();
tb.Text = "Book " + i.ToString() + " Title";
tb2.Text = "Book " + i.ToString() + " Author";
tb.ID = "TextBoxTitle" + i.ToString();
tb2.ID = "TextBoxAuthor" + i.ToString();
pnlBooks.Controls.Add(tb);
pnlBooks.Controls.Add(tb2);
pnlBooks.Controls.Add(new LiteralControl("<br />"));
}
}
}

You don't really need to keep track of your programmatically or dynamically added controls. It's true that somehow someone has to keep track of them, but it's not you who should be doing so.
Understanding the Page Life-cycle in ASP.NET Web Forms is a must for any ASP.NET developer. Sooner or later you'll run into this sort of problems that would be greatly simplified if you really understood the underlying mechanics of the page.
Each time a request is made to the server, the whole page must be assembled from scratch. You can read (please do) on the web the many steps or stages that make up the Page Life-cycle for an ASP.NET page, but for you to have a rough idea on how this works:
When the request is made, the .aspx file is parsed and a memory source code created from it. This stage is known as the Instantiation stage, and the page's control hierarchy is created at this point.
After that, page goes through the Initialization phase, in which the page's Init event is fired. This is "the place" to add controls dynamically.
LoadViewState phase comes next. At this point, the information of the controls that are part of the page's control hierarchy get their "state" updated to make them return to the state they were before the postback. (This stage doesn't happen on the first time the page is accessed, it's a postback-only stage).
LoadPostData phase is when the data that has been posted to the server (by submitting the form) is loaded into controls. This stage is barely known to beginner ASP.NET developers, because they assume that all "state preservation" that is automatically enforced by ASP.NET engine comes from the magical Viewstate.
NOTE: If you are really serious about this, you can learn A LOT from this guy here: Understanding ASP.NET View State
What you need to remember from all the above now is that: in order for your dynamically generated controls to "have" their data "glued" together into the control's state after submitting the form by clicking this button Then I would have a button they click that would save the textbox values into the database., you need to add the controls to the page at each round-trip to the server.
The recommended way of doing so is in the Page_Init, because it comes before the LoadViewsate and LoadPostData stages where the control's state is populated.
In your case though, you don't know how many controls to add until the user fills that information on the first form submission. So, you need to find a way to add the controls to the page each time the page loads after the user entered the number of desired controls.
NOTE: You could get away with adding the controls on the btnBookQty_Click and have their data preserved correctly, because ASP.NET "plays catch-up" on the controls, but that's beyond the scope and purpose of this answer.
Add a private field to act as a boolean flag and to indicate the number of controls to add.
Create a private method that add the controls into the page, taking as argument the number of controls to add.
Call that method from within the Page_Init event handler, only if the flag dictates that some fields must be added.
In btnBookQty's click event handler set the flag to the number provided by the user of the page, and...
Call the method to create the dynamically generated controls from within btnBookQty_Click.
Here's a template code of what you need. Notice how HowManyControls property is stored in the Session to "remember" that value across postbacks:
private int HowManyControls {
get
{
if (Session["HowManyControls"] == null) return 0;
else return (int)Session["HowManyControls"];
}
set
{
Session["HowManyControls"] = value;
}
}
protected void Page_Init(object sender, EventArgs e)
{
if (Page.Ispostback && HowManyControls > 0)
{
//generate the controls dynamically
GenerateControls(HowManyControls);
}
}
protected void btnBookQty_Click(object sender, EventArgs e)
{
//get the number of controls to generate dynamically from the user posted values
HowManyControls = Convert.ToInt32(TextBox1.Text);
//generate the controls dynamically
GenerateControls(HowManyControls);
}
protected void btnSaveToDatabase_Click(object sender, EventArgs e)
{
//iterate on the control's collection in pnlBook object.
for (int i = 1; i <= HowManyControls; i++)
{
//save those value to database accessing to the control's properties as you'd regularly do:
TextBox tb = (TextBox)pnlBooks.FindControl("TextBoxTitle" + i.ToString());
TextBox tb2 = (TextBox)pnlBooks.FindControl("TextBoxAuthor" + i.ToString();
//store these values:
tb.Text;
tb2.Text;
}
}
private void GenerateControls(int count)
{
if (count == 0) { return; }
for (int i = 1; i <= count; i++)
{
TextBox tb = new TextBox();
TextBox tb2 = new TextBox();
tb.Text = "Book " + i.ToString() + " Title";
tb2.Text = "Book " + i.ToString() + " Author";
tb.ID = "TextBoxTitle" + i.ToString();
tb2.ID = "TextBoxAuthor" + i.ToString();
pnlBooks.Controls.Add(tb);
pnlBooks.Controls.Add(tb2);
pnlBooks.Controls.Add(new LiteralControl("<br />"));
}
}
EDIT
I had forgotten that ViewState is not available during Page_Init. I've now modified the answer to use Session instead.

When somebody says that "You need to keep track of the controls you create or recreate them" it means that you need to store them between postbacks.
In ASP.NET persistance can means Session variables, ViewStates and other means
See this link http://msdn.microsoft.com/en-us/magazine/cc300437.aspx
Create a list of the textboxes that you created and store it on a Session
private void CreateOrLoadTextBoxes(int numTextBoxes)
{
List<TextBox> lstControls ;
//if its the first time the controls need to be created
if(Session["lstTitleControls"] == null)
{
lstTbTitles = new List<TextBox>(numTextBoxes) ;
lstTbAuthors = new List<TextBox>(numTextBoxes) ;
//create the controls for Book Titles
for (int i = 1; i <= numTextBoxes; i++)
{
TextBox tb = new TextBox();
tb.Text = "Book " + i.ToString() + " Title";
tb.ID = "TextBoxTitle" + i.ToString();
lstTbTitles.Add(tb) ;
}
//Create the controls for Author
for (int i = 1; i <= numTextBoxes; i++)
{
TextBox tb2 = new TextBox();
tb2.Text = "Book " + i.ToString() + " Author";
tb2.ID = "TextBoxAuthor" + i.ToString();
lstTbAuthors.Add(tb2) ;
}
//store the created controls on ViewState asociated with the key "lstTitleControls" and "lstAuthorControls"
// each time you store or access a ViewState you a serialization or deserialization happens which is expensive/heavy
Session["lstTitleControls"] = lstTbTitles ;
Session["lstAuthorControls"] = lstTbAuthors ;
}
else
{
//restore the list of controls from the ViewState using the same key
lstTbTitles = (List<TextBox>) Session["lstTitleControls"];
lstTbAuthors = (List<TextBox>) Session["lstAuthorControls"];
numTextBoxes = lstTbTitles.Count() ;
}
//at this moment lstTbTitles and lstTbAuthors has a list of the controls that were just created or recovered from the ViewState
//now add the controls to the page
for (int i = 1; i <= numTextBoxes; i++)
{
pnlBooks.Controls.Add(lstTbTitles[i]);
pnlBooks.Controls.Add(lstTbAuthors[i]);
pnlBooks.Controls.Add(new LiteralControl("<br />"));
}
}
protected void Page_Load(object sender, EventArgs e)
{
CreateOrLoadTextBoxes(10) ;
}
As you have noticed I am calling the CreateOrLoadTextBoxes with a fixed value of 10
Is up to you to chane this code to take the value from the text box and call this as needed

RequiredFieldValidator not working in a repeater

I'm trying to dynamically add a RequiredFieldValidator to a RadioButtonList in a repeater, but it fails with the error:
Unable to find control id 'rblAccessory_40' referenced by the 'ControlToValidate' property of ''.
The code for this section is:
if ((e.Item.ItemType != ListItemType.Header) && (e.Item.ItemType != ListItemType.Footer))
{
Label lblAccID = (Label)e.Item.FindControl("lblAccID");
RadioButtonList rblCondition = (RadioButtonList)e.Item.FindControl("rblCondition");
rblCondition.ID = "rblAccessory_" + lblAccID.Text;
if (conditionList.Count() > 0)
{
RequiredFieldValidator rfv = new RequiredFieldValidator();
rfv.ControlToValidate = "rblAccessory_" + lblAccID.Text;
rfv.ErrorMessage = "Please complete the accessories section";
pnlValidation.Controls.Add(rfv);
rblCondition.DataSource = conditionList;
rblCondition.DataValueField = "id";
rblCondition.DataBind();
}
foreach (ListItem li in rblCondition.Items)
{
li.Text = "";
li.Value = "AccessoryID_" + lblAccID.Text + "-ConditionID_" + li.Value;
}
}
}
It is definitely finding the RadioButtonList (rblCondition) because the data is binding correctly at this point:
rblCondition.DataSource = conditionList;
rblCondition.DataValueField = "id";
rblCondition.DataBind();
So I don't understand why the error says it is unable to find the control ID.
I've tried specifying the control ID manually, as below:
rfv.ControlToValidate = "rblAccessory_" + lblAccID.Text;
and have also tried:
rfv.ControlToValidate = rblCondition.ID;
lblAccID is a hidden text field used to store the ID of the row in the repeater.

Assign the control to validate property AFTER the ItemCreated event. I know this sounds weird, how would you still have the reference to the dynamically created control? I've gotten around this by keeping a reference to a List<Action> reference which I add things to during ItemCreated to be executed later.
In your control class you'll declare your List<Action> object:
List<Action> deferringControlToValidateUntilPreRender = new List<Action>();
Inside the ItemCreated event you'll have a line that looks like:
deferringControlToValidateUntilPreRender.Add(() => rfv.ControlToValidate = rblCondition.UniqueID);
And then, later, perhaps in PreRender:
foreach(var deferredAction in deferringControlToValidateUntilPreRender) action();

Since the RequiredFieldValidator is client-side code, you need to use the client id of the control. Like this:
rfv.ControlToValidate = rblCondition.ClientID;
Some more information from MSDN if you are interested:
Control.ClientIDMode Property
Also, an SO discussion on the differences between ClientID and UniqueID (as referenced in #MushinNoShin's answer, which, IMHO, is incorrect):
Why is there a difference between ClientID and UniqueID?

textboxes lose value on postback

i have about 4 textboxes on my webpage...some are asp:textboxes while others are input type="text".
the input textbox is populated through a javascript popup calender control while asp.net textbox is populated by typing. The initial values of these textboxes are retrieved from a database.
When a user changes these values, they are not saved and the textboxes are cleared out after the submit button is clicked. Please help resolve this confusion. Thanks.
thanks for your reply but it is still not working.....
i have put this code in my page load event
if (Page.IsPostBack)
{
if (ViewState["stock"] != null)
TextBoxMaterial.Text = ViewState["stock"].ToString();
if (ViewState["supplier"] != null)
TextBoxSupplier.Text = ViewState["supplier"].ToString();
if(ViewState["matTime"] != null)
TextBoxMatTime.Text = ViewState["matTime"].ToString();
if(ViewState["prodTime"] != null)
TextBoxProdTime.Text = ViewState["prodTime"].ToString();
if (ViewState["shipTime"] != null)
TextBoxShipTime.Text = ViewState["shipTime"].ToString();
if(ViewState["cmr"] != null)
cmrDue.Value = ViewState["cmr"].ToString();
if(ViewState["kc"] != null)
kcDue.Value = ViewState["kc"].ToString();
}
and also put the below code in the onclick event for the button
ViewState["stock"] = TextBoxMaterial.Text;
ViewState["supplier"] = TextBoxSupplier.Text;
ViewState["matTime"] = TextBoxMatTime.Text;
ViewState["prodTime"] = TextBoxProdTime.Text;
ViewState["shipTime"] = TextBoxShipTime.Text;
ViewState["cmr"] = cmrDue.Value.ToString();
ViewState["kc"] = kcDue.Value.ToString();
string prodLine = DDProdLine.SelectedValue;
string stock1 = DDMaterial.SelectedValue;
string stock2 = ViewState["stock"].ToString();
string supplier = ViewState["supplier"].ToString();
string billet = RBBillet.SelectedValue;
string matTime1 = ViewState["matTime"].ToString();
string matTime2 = DDMatTime.SelectedValue;
string prodTime1 = ViewState["prodTime"].ToString();
string prodTime2 = DDProdTime.SelectedValue;
string shipTime1 = ViewState["shipTime"].ToString();
string shipTime2 = DDShipTime.SelectedValue;
CultureInfo cultureInfo = CultureInfo.CurrentCulture;
string format = CultureInfo.CurrentCulture.DateTimeFormat.ShortDatePattern.ToString();
string cmr = ViewState["cmr"].ToString();
string kc = ViewState["kc"].ToString();
string x = cmr.Substring(3, 2);
string y = cmr.Substring(0, 2);
string z = cmr.Substring(6, 4);
string x1 = kc.Substring(3, 2);
string y1 = kc.Substring(0, 2);
string z1 = kc.Substring(6, 4);
string finalCmr = x + "/" + y + "/" + z;
string finalKC = x1 + "/" + y1 + "/" + z1;
DateTime dt = DateTime.ParseExact(finalCmr, format, cultureInfo);
DateTime cr = DateTime.ParseExact(finalKC, format, cultureInfo);
string custDate = dt.ToString("dd/mm/yyyy");
string kcDate = cr.ToString("dd/mm/yyyy");
string id = Request.QueryString["id"];
bool success = true;
TextBoxProdComment1.Text = stock2 + "," + supplier + matTime1 + "," + prodTime1 + "," + shipTime1 + "," + custDate
+ "," + kcDate;
try
{
success = CRTopButtons.SaveProdTable(id, prodLine, stock1, supplier, billet, matTime1, matTime2, prodTime1,
prodTime2, shipTime1, shipTime2, custDate, kcDate);
}
catch (Exception e)
{
TextBoxProdComment2.Text = e.Message;
System.Diagnostics.Trace.Write(e.StackTrace);
}
the textboxes still clear out and none of it is readonly..........
please help

I had a similar problem and The Solution to "Losing data changed by javascript during postback"
is best described by this article
ViewState and Readonly Property of Textbox
for example let's say we have this asp.net control:
<asp:TextBox ID="txtName" runat="server" EnableViewState= "false" ReadOnly="true" />
if you change the value of this control through javascript in the client side it will not be propagated via postback in the serverside...whatever you do with javascript unless you remove readonly="true". Now there is a solution to this problem as described in the article above.
Simply put this in the PageLoad event
if (!IsPostBack)
txtName.Attributes.Add("readonly","readonly");
and you're done. Just don't forget to remove ReadOnly="true" or Enable="false" if your intent was to disable the control from editing just use the snippet above. Don't forget to remove Enable="false" if you put it on.

Another thing I ran into... If you're using an ASP.NET TextBox Control (for example), and it's READONLY or DISABLED, the postback won't catch the changed value.
Per my issue, I was changing the value of the control thru javascript and even though the browser rendered the change, on the postback, the control still retained the original value.
Seems a common problem too... javascript kicks off a custom ASCX calendar control and result is injected by javascript, into the textbox. Users shouldn't be allowed to directly modify textbox value...
string strDate = Request.Form["id_of_input_element"].ToString();
I ultimately used the above to um, "reset" the control, after the postback, to it's changed value!

The <input> textboxes won't save their state after postback. ASP.NET does not handle that for you.
If you put code in your Page_Load event to set the values of the ASP.NET textboxes, the values that were posted back will not be saved, because Page_Load happens after the child control states are restored in the ASP.NET page lifecycle. The values are already restored by ASP.NET, but you are overwriting their restored values.
The correct thing to do to fix #2 is to check Page.IsPostBack before loading your initial state, like this:
if ( !Page.IsPostBack )
{
// set the textbox initial states from the database
}
UPDATE:
There are two ways to solve problem #1. One thing you could do is to use the Request.Form[] collection to retrieve the posted back value manually, like this:
string strDate = Request.Form["id_of_input_element"].ToString();
The other thing you could do, and this is what I'd recommend if you can, is to change the <input> element to an ASP.NET textbox, and hook up any client-side Javascript events to that. Then ASP.NET will completely handle your postback.

i found this when looking for an answer to the same type of problem and now that i found my problem i thought it could help someone else putting it here.
in my case i had a tag <form> inside the <form> of my controls, so, if you didnt resolve your problem with above i sugest search for a <form> lost inside your <form>.
hope it helps for some cases.

If I get you're asking for right, I think you're trying to make those textboxes readonly. If so, I had this problem before and solved it by making the textboxes readonly using C# not ASP.NET, I just added lines like textboxName.Attributes.Add("readonly", "readonly"); in the Page_Load and it worked just fine. This solution I found here on Stackoverflow

instead of TextBoxPassword.Text=Password
use
TextBoxPassword.Attributes["value"]=Password

It seems that your viewstate is disabled. Enable the viewstate in Page directive.

Accessing hidden-input values edited by JavaScript

I have dynamically created hidden input controls in a C# code-behind file, and then populated their values with JavaScript. I now want to access these variables in C#.
Firebug shows that the values do change with JavaScript, but I'm getting the original values back in the code behind. Any insight would be much appreciated.
JavaScript:
function injectVariables(){
var hidden = document.getElementById("point1");
hidden.value = 55;
var hidden2 = document.getElementById("point2");
hidden2.value = 55;
var hidden3 = document.getElementById("point3");
hidden3.value = 55;
alert("values changed");
}
ASPX:
<asp:Button OnClick="Update_PlanRisks" OnClientClick="injectVariables()" Text="updatePlanRisks" runat="server" />
C#:
protected override void CreateChildControls()
{
base.CreateChildControls();
int planId = Convert.ToInt32(Request.QueryString.Get("plan"));
planRisks = wsAccess.GetPlanRiskByPlanId(planId);
foreach (PlanRisk pr in planRisks)
{
HtmlInputHidden hiddenField = new HtmlInputHidden();
hiddenField.ID= "point" + pr.Id;
hiddenField.Name = "point" + pr.Id;
hiddenField.Value = Convert.ToString(pr.Severity);
this.Controls.Add(hiddenField);
}
}
protected void Update_PlanRisks(object sender, EventArgs e)
{
foreach (PlanRisk pr in planRisks)
{
int planRiskId = pr.Id;
string planRiskName = "point" + pr.Id;
HtmlInputHidden hiddenControl = (HtmlInputHidden) FindControl(planRiskName);
string val = hiddenControl.Value;
}
}

This is one way to get the value from the request...
string point1 = Request.Form["point1"];

In CreateChildControls you are explicitly setting the value of the hidden field(s). CreateChildControls runs each time during the page lifecycle (potentially multiple times), when you click submit, the page posts back and runs through the entire lifecycle again - including CreateChildControls - before running the click handler Update_PlanRisks.
The simplest way to avoid this problem is to check if you are in PostBack before setting the value of your hidden fields:
if(!IsPostBack)
{
hiddenField.Value = Convert.ToString(pr.Severity);
}

Dynamically changing css style in c#?

I have some link buttons in which I am dynamically adding a style to it. I am doing the following in a method:
LinkButton lb = new LinkButton();
lb.Style["font-weight"] = "bold";
When the another link is clicked, it should unbold the link button that is bold and bold the currently clicked one, so in the method that is doing this, I have tried:
lb.Style["font-weight"] = "none";
The above does not work though, the previously selected link stays bold.
I just realized the possible problem. I am creating multiple links and what it looks like is that since all the links are named lb, it never removes the bold. I am trying to think of a way for it to remember the previously selected link and to only unbold that one.

Can I suggest an alternative approach?
Set a CSS Style:
.selected { font-style: bold; }
When a link is clicked set that link's CSS class to "selected" and the others to "";
EDIT: To accommodate for existing Css Class
const string MY_CLASS = "links";
lb1.CssClass = MY_CLASS + " selected"; // selected
lb.CssClass = MY_CLASS; // not selected
You can quickly get into trouble when defining inline styles, in that they're difficult to overwrite.
EDIT 2:
Something like this code should work. You may have to loop through all the LinkButtons in the list, but I don't think so. I'd just turn off ViewState on the LinkButtons.
// container for links. so you can reference them
// outside of the creation method if you wish. I'd probably call this method in the
// Page_Init Event.
List<LinkButton> listOfLinks = new List<LinkButton>();
const string MY_LB_CLASS = "linkButton"; // generic lb class
private void createSomeLinks() {
for (int i = 0; i < 10; i++) {
// create 10 links.
LinkButton lb = new LinkButton()
{
ID = "lb" + i,
CssClass = MY_LB_CLASS
};
lb.Click += new EventHandler(lb_Click); // Add the click event
}
// You can bind the List of LinkButtons here, or do something with them.
}
void lb_Click(Object sender, EventArgs e) {
LinkButton lb = sender as LinkButton; // cast the sender as LinkButton
if (lb != null) {
// Make the link you clicked selected.
lb.CssClass = MY_LB_CLASS + " selected";
}
}

Try lb.Style.Remove("font-weight"). I didn't test it, but you can try it out.
Alternatively, have you tried settings the Font.Bold property?
lb.Font.Bold = true;

Try ListBox1.Attributes.Add("style","font-weight:bold");
and ListBox1.Attributes.Add("style","font-weight:normal");
or even better is
// css
.active {font-weight:bold}
.notactive {font-weight:normal}
//c#
ListBox1.CssClass = "active";
ListBox1.CssClass = "notactive ";

you could try lb.Style.Remove("font-weight");

set the font bold in the click event of the link button and set the enable view state property to false in the click event itself which will reset the link to the normal foam in the other click