the dynamic controls went missing right after i click it, why is this happening, and how do i fix it.
protected void Page_Load(object sender, EventArgs e)
{
/*DropDownList1_SelectedIndexChanged(sender, e);
Label1.Text += "<br/>huh?";
Label1.Text = MapPath("dawd");*/
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
//PlaceHolder1.Controls.Clear();
for (int i = 0; i < DropDownList1.SelectedIndex + 1; i++)
{
CheckBox cb = new CheckBox();
cb.AutoPostBack = true;
cb.CheckedChanged += new EventHandler(cb_CheckedChanged);
PlaceHolder1.Controls.Add(cb);
PlaceHolder1.Controls.Add(new LiteralControl("<br/>"));
}
}
void cb_CheckedChanged(object sender, EventArgs e)
{
//DropDownList1_SelectedIndexChanged(sender, e);
Label1.Text += "<br/>adsd";
//throw new NotImplementedException();
}
cheers, Jaf
Dynamically created controls have to be recreated in every postback, or they will not be available and non of their events will fire.
You are only ever adding the checkboxes when the dropdownlist changes, so any other postback will not add them.
It is best to create your dynamic controls on the page OnInit event.
Read about the page life cycle here.
Create a panel
Do not create on page_load
Add this code
protected override void CreateChildControls()
{
base.CreateChildControls();
loadCheckbox();
}
public void loadCheckbox()
{
int checkCount = 10;
CheckBox[] chk = new CheckBox[checkCount];
for(int i == 0; i<=10; i++)
{
chk[i] = new CheckBox();
chk[i].ID = rCmt.cmtkey;
chk[i].Text = rCmt.rootcommitteename;
Panel1.Controls.Add(chk[i]);
}
}
Related
I am trying to figure out how to use a click event handler for my 4 buttons that I have generated dynamically without putting any code in page init or oninit. I have one button that once clicked it generates 4 more buttons. The click event handler for these 4 buttons is not working. Here is the code. Has anybody figured out a way to use the click events in asp.net c# without first putting it in page_load? If I can solve this problem, I can solve my real problem in a bigger scenario.:
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
for (int i = 0; i < 4; i++)
{
Button b = new Button();
b.ID = i.ToString();
b.Text = "ClickMe";
b.Visible = true;
b.Click += new EventHandler(b_click);
PlaceHolder1.Controls.Add(b);
}
}
void b_click(object sender,EventArgs e)
{
Label1.Text = "ok";
}
Make sure the ID of your dynamic controls include a distinct keyword. In my example below I prepended "DYNAMIC_" to their ID. Then override OnPreRender() like this:
protected override void OnPreRender(EventArgs e)
{
if (Page.IsPostBack && !IsPostBackEventControlRegistered)
{
var controlName = this.Request.Form.AllKeys.SingleOrDefault(key => key.Contains("DYNAMIC_"));
processEventForDynamicControl(controlName);
}
base.OnPreRender(e);
}
private void processEventForDynamicControl(string controlName)
{
//Do your dynamic button click processing here
}
Of course, if your dynamic controls use doPost() (which sadly Button doesn't) you can retrieve the control directly from __EVENTTARGET like this:
var controlName = Request.Params.Get("__EVENTTARGET")
You want to load controls inside Page_Load. Otherwise, they are not in control tree, and they won't be able to trigger b_click event.
public int Counter
{
get { return (int?) ViewState["Counter"] ?? 0; }
set { ViewState["Counter"] = value; }
}
protected void Page_Load(object sender, EventArgs e)
{
var counter = Counter;
for (int i = 0; i < counter; i++)
{
Button b = new Button();
b.ID = i.ToString();
b.Text = "ClickMe";
b.Visible = true;
b.Click += b_click;
PlaceHolder1.Controls.Add(b);
}
}
protected void Button1_Click(object sender, EventArgs e)
{
Counter = 4;
for (int i = 0; i < 4; i++)
{
Button b = new Button();
b.ID = i.ToString();
b.Text = "ClickMe";
b.Visible = true;
b.Click += b_click;
PlaceHolder1.Controls.Add(b);
}
}
void b_click(object sender, EventArgs e)
{
Label1.Text = "ok";
}
Note: If you plan to load inside Page_Init, you want to use Session instead of ViewState.
Basically I got it working.There is no way around it. You have to use Oninit or Page_load and put your b.Click += new EventHandler(b_click) code there in addition to the PlaceHolder1.Controls.Add(b); there as well,for the event handler to register properly with the button. The problem with this method is that it places the button on top of the PlaceHolder portion of the web page which is not what I want. I want to beable to place the button at a particular position in the web page. So how do you go around doing this? Basically after the PlaceHolder1.Controls.Add(b) simply make the button invisible. Then in the when you are ready to place the button in a particular part of your html call PlaceHolder1.Controls.Add(b) again and make it visible. That works for me. If anyone needs help with this I can post some sample code and you can test it for yourself. Thanks all.
I have a scenario. following is the code:
Home.aspx.cs
protected void Button1_Click(object sender, EventArgs e)
{
try
{
if (!String.IsNullOrEmpty(txtbox_query.Text.Trim()))
{
if (isTrue)
{
// To do statements
}
else
{
List<RequestAndResponse.Parameter> parameters = request.getParameter(txtbox_query.Text.Trim(), sourcePath, parameterValue);
Session["Data"] = parameters;
Response.Redirect("Result.aspx",false);
}
}
}
catch (Exception error)
{
Response.Write(error.Message);
}
}
Result.aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
parameters = (List<RequestAndResponse.Parameter>)Session["Data"];
ContentPlaceHolder content = (ContentPlaceHolder)this.Form.FindControl("MainContent");
for (int j = 1; j <= _arrViewState; j++)
{
string _id = j.ToString();
TextBox txtfname = new TextBox();
txtfname.ID = "TextBox_" + _id + "_";
txtfname.Width = 160;
txtfname.Text = parameters[(j - 1)].Value.ToUpper();
txtfname.Attributes.Add("style", "color:#015D84;font-weight:bold;font-size:12px;padding:10px;");
txtfname.EnableViewState = true;
content.Controls.Add(txtfname);
content.Controls.Add(new LiteralControl("<br/>"));
}
Button btnSubmit = new Button();
btnSubmit.ID = "btnSubmit";
btnSubmit.Text = "Submit";
btnSubmit.Click += new System.EventHandler(btnSubmit_click);
btnSubmit.Enabled = false;
content.Controls.Add(btnSubmit);
}
protected void btnSubmit_click(object sender, EventArgs e)
{
// How to find the dynamically created textbox
}
Now How to find the dynamically created controls
I know the basic like:
Form.FindControl("TextBox ID");
But here i dont know the textbox id and also i even dont know how many textbox will be their as it totally depends on user input i.e. from 2 TO N textboxes
What i want is on bttn_Click i will fetch the text from all the textboxes
How will i achieve this.
Also i want to check if all Textbox is empty or not on bttn_Click
Enumerate controls as follows
protected void btnSubmit_click(object sender, EventArgs e)
{
ContentPlaceHolder content = (ContentPlaceHolder)this.Form.FindControl("MainContent");
foreach (Control c in content.Controls)
{
if (c is TextBox)
{
TextBox txt = (TextBox)c;
// do something, e.g. Response.Write(txt.Text);
}
}
}
I want to add buttons to my page dynamically. It will depend on the number of results from a SELECT statement. I
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
for (int i = 0; i < Query.length; i++)
{
Button btn = new Button();
btn.ID = "Button" + i;
btn.Click += new EventHandler(btn_Click());
btn.Text = i.ToString();
pagingPanel.Controls.Add(btn);
}
}
}
But I want each button to have it's own custom event handler. If I click one button, I want it do have a different result than if I click another. I would like to do something like this where I can pass an aditional parameter:
protected void btn_Click(object sender, EventArgs e, string test)
{
System.Diagnostics.Debug.WriteLine(test);
}
Perhaps I don't know which objects to pass? Or maybe I am approaching this the wrong way.
How do I achieve the desired results?
Try this:
protected void Page_Load(object sender, EventArgs e)
{
// you do not use !IsPostBack here
//count of func must be equal with 'Query.Length'
string[,] arr ={
{"func1","hello world"},
{"func2","Hello ASP.NET"}
};
for (int i = 0; i < Query.Length; i++)//I assume length is 2
{
Button btn = new Button();
btn.ID = arr[i, 0];
btn.CommandArgument = arr[i, 1];
btn.Click += new EventHandler(btn_Click);
btn.Text = i.ToString();
pagingPanel.Controls.Add(btn);
}
}
protected void btn_Click(object sender, EventArgs e)
{
Button btn = (Button)sender;
System.Reflection.MethodInfo methodInfo = typeof(_Default2).GetMethod(btn.ID); //_Default2 is class name of code behind
if (methodInfo != null)
{
object[] parameters = new object[] { btn.CommandArgument};
methodInfo.Invoke(this,parameters);
}
}
public void func1(object args)
{
string test = args.ToString();
Response.Write(test);
}
public void func2(object args)
{
string test = args.ToString();
Response.Write(test);
}
First and foremost - you have to create buttons whether it is postback or not. The button click is the reason for the postback, if you don't have buttons - what will be clicking?
Second, add to your page class:
Dictionary<Button, ButtonInfo> fButtonLookup = new Dictionary<Button, ButtonInfo>();
Then, where you create buttons:
fButtonLookup.Clear();
for (int i = 0; i < Query.length; i++)
{
Button btn = new Button();
fButtonLookup.Add(btn, new ButtonInfo() { whatever information about this button you want to keep});
...
}
Then, in your button click:
protected void btn_Click(object sender, EventArgs e)
{
Button btn = (Button)sender;
if (fButtonLookup.ContainsKey(btn))
{
ButtonInfo info = fButtonLookup[btn];
// do waht you need with button information
}
}
You could just check sender to see which button was clicked:
protected void btn_Click(object sender, EventArgs e)
{
if (sender == btnOne)
performBtnOne("foo");
else if (sender == btnTwo)
performButtonTwo("bar");
}
To expand on itsme86...
protected void btn_Click(object sender, EventArgs e)
{
Button btn = (Button)sender; //Now you have an instantiated version of the button pressed.
switch (btn.Name)
{
case "foo":
performBtnOne();
break;
case "bar":
performBtnTwo();
break;
default:
performUnexpectedButton();
break;
}
}
public partial class Default2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
GenerateButtons generate = new GenerateButtons();
generate.Generate5Controls(PlaceHolder1);
}
}
class GenerateButtons
{
PlaceHolder placeHolder;
public void Generate5Controls(PlaceHolder placeH)
{
placeHolder = placeH;
for (int i = 0; i < 5; i++)
{
Button newBtn = new Button();
newBtn.Click += btn_Click;
newBtn.Text = "PageLoadButton Created. Number: "+i;
placeHolder.Controls.Add(newBtn);
}
}
public void btn_Click(object sender, EventArgs e)
{
Button newBTN = new Button();
newBTN.Text = "A New Button was added by the button event btn_click";
newBTN.Click += btn2_Click;
placeHolder.Controls.Add(newBTN);
}
public void btn2_Click(object sender, EventArgs e)
{
Button newBTN = new Button();
newBTN.Text = "A New Button was added by the button event btn2_click";
placeHolder.Controls.Add(newBTN);
}
}
I want the events btn_click & btn2_click to fire every post back.. When i click the button that was programmatically created it disappears after each postback and its event doesnt fire (btn2_click). I know i could generate the button at the postback.. But I dont want to do that!! I want to know how I could update the state of the placeholder... so that the only button will appear and the 5 buttons generated in Generate5Controls(PlaceHolder placeH) to disappear.
I could use a bool Viewstate to prevent this generate.Generate5Controls(PlaceHolder1); from being execute..
But the question is how do I make the programmatically generated button to appear!?
You should generate controls on every PostBack or you can generate controls once, save in session and add generated controls from session on page_load event.
protected void Page_Load(object sender, EventArgs e)
{
if(Session["GeneratedButtons"] == null)
{
GenerateButtons generate = new GenerateButtons();
generate.Generate5Controls(PlaceHolder1);
}
else
{
List<Control> generatedControls = Session["GeneratedButtons"] as List<Control>;
foreach(Control oneControl in generatedControls)
{
PlaceHolder1.Controls.Add(oneControl);
}
}
}
class GenerateButtons
{
PlaceHolder placeHolder;
public void Generate5Controls(PlaceHolder placeH)
{
placeHolder = placeH;
List<Control> generatedControls = new List<Control>();
for (int i = 0; i < 5; i++)
{
Button newBtn = new Button();
newBtn.Click += btn_Click;
newBtn.Text = "PageLoadButton Created. Number: "+i;
placeHolder.Controls.Add(newBtn);
AddControlToSession(newBtn);
}
}
public void btn_Click(object sender, EventArgs e)
{
Button newBTN = new Button();
newBTN.Text = "A New Button was added by the button event btn_click";
newBTN.Click += btn2_Click;
placeHolder.Controls.Add(newBTN);
AddControlToSession(newBtn);
}
public void btn2_Click(object sender, EventArgs e)
{
Button newBTN = new Button();
newBTN.Text = "A New Button was added by the button event btn2_click";
placeHolder.Controls.Add(newBTN);
AddControlToSession(newBtn);
}
private void AddControlToSession(Control ctrl)
{
List<Control> generatedControls = Session["GeneratedButtons"] as List<Control>;
if(generatedControls == null)
{
generatedControls = new List<Control>();
}
generatedControls.Add(ctrl);
Session["GeneratedButtons"] = generatedControls;
}
}
I'm trying to create a composite ASP.NET control that let's you build an editable control collection.
My problem is that when I press the add or postback button (which does nothing other than to postback the form) any values entered in the text boxes are lost.
I can't get it to work when the number of controls change between postbacks. I need to basically be able to recreate the control tree at two different times in the control life-cycle depending on the view state property ControlCount.
This test can be used to reproduce the issue:
public class AddManyControl : CompositeControl
{
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
EnsureChildControls();
}
protected override void CreateChildControls()
{
var count = ViewState["ControlCount"] as int? ?? 0;
for (int i = 0; i < count; i++)
{
var div = new HtmlGenericControl("div");
var textBox = new TextBox();
textBox.ID = "tb" + i;
div.Controls.Add(textBox);
Controls.Add(div);
}
ViewState["ControlCount"] = count;
var btnAdd = new Button();
btnAdd.ID = "Add";
btnAdd.Text = "Add text box";
btnAdd.Click += new EventHandler(btnAdd_Click);
Controls.Add(btnAdd);
var btnPostBack = new Button();
btnPostBack.ID = "PostBack";
btnPostBack.Text = "Do PostBack";
Controls.Add(btnPostBack);
}
void btnAdd_Click(object sender, EventArgs e)
{
ViewState["ControlCount"] = (int)ViewState["ControlCount"] + 1;
}
protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);
// If I remove this RecreateChildControls call
// the collection lags behind each postback
// because the count is incremented in the btnAdd_Click event handler
// however, the values are not lost between postbacks
RecreateChildControls();
}
}
If you want to play with ASP.NET's custom controls, you have to play by its rule and its picky! When you start to play with the OnPreRender in a custom control, you know you're on the wrong track 90% of the time.
Generally, the best way to use the ViewState is to declare a property backed up by it, just like the standard ASP.NET controls do (.NET Reflector has been my teacher for years!). This way, it will be read and saved naturally during the event's lifecycle.
Here is a code that seems to do what you want, quite naturally, without any trick:
public class AddManyControl : CompositeControl
{
private void AddControl(int index)
{
var div = new HtmlGenericControl("div");
var textBox = new TextBox();
textBox.ID = "tb" + index;
div.Controls.Add(textBox);
Controls.AddAt(index, div);
}
protected override void CreateChildControls()
{
for (int i = 0; i < ControlsCount; i++)
{
AddControl(i);
}
var btnAdd = new Button();
btnAdd.ID = "Add";
btnAdd.Text = "Add text box";
btnAdd.Click += new EventHandler(btnAdd_Click);
Controls.Add(btnAdd);
var btnPostBack = new Button();
btnPostBack.ID = "PostBack";
btnPostBack.Text = "Do PostBack";
Controls.Add(btnPostBack);
}
private int ControlsCount
{
get
{
object o = ViewState["ControlCount"];
if (o != null)
return (int)o;
return 0;
}
set
{
ViewState["ControlCount"] = value;
}
}
void btnAdd_Click(object sender, EventArgs e)
{
int count = ControlsCount;
AddControl(count);
ControlsCount = count + 1;
}
}
I believe you have to add the control into the view state.