Develop Reference

how to bind more than one dropdownlist without refreshing?

protected void Page_Load(object sender, EventArgs e)
{
bindbranches();
bindbranches1();
}
public void bindbranches()
{
DataTable dtbranch = new DataTable();
dtbranch = objsupplyBAL.getbrnch();
ddlbranch.DataSource = dtbranch;
ddlbranch.DataBind();
ddlbranch.Items.Add(new ListItem("--select--", "0"));
ddlbranch.SelectedIndex = ddlbranch.Items.Count - 1;
}
public void bindbranches1()
{
DataTable dt = new DataTable();
dt = objsupplyBAL.getbrnch();
ddlbranch1.DataSource = dt;
ddlbranch1.DataBind();
ddlbranch1.Items.Add(new ListItem("--select--", "0"));
ddlbranch1.SelectedIndex = ddlbranch1.Items.Count - 1;
}
My dropdownlist's are not binding without refreshing.If i select one dropdownlist another one is refreshing. What i have to add extra to my code. Can any one tell...

protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
bindbranches();
bindbranches1();
}
}
if you add this...it's work properly ...first try this...

The reason that is happening is you are running the code every time the page postsback, try the following to only populate the items once (on the initial page load) :
protected void Page_Load(object sender, EventArgs e) {
if (!this.IsPostBack) {
bindbranches();
bindbranches1();
}
}
Alternatively you can also handle the Page.Init event to run this code, this will change the dropdowns when the page is first loaded and will keep the values throughout subsequent postbacks :
protected void Page_Init(object sender, EventArgs e) {
bindbranches();
bindbranches1();
}
If you want the second dropdown to refresh only when the first item is selected, try the following solution :
protected void ddlbranch_SelectedIndexChanged(object sender, EventArgs e) {
bindbranches1();
}
And bind ddlbranch_SelectedIndexChanged to the selected index changed event of your ddlbranch control. This will only run the code when the page is initially loaded and when the user selects an item from the ddlbranch dropdown

You will have to set AutoPostBack Property of the drop down to true if you want to fill another drop down on change of one drop down so on change event will start executing
Loot # http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.listcontrol.autopostback.aspx

restoring dropdown selected values in c# after refresh by retrieving values from database

I have created a dropdownlist in my webpage which is outside the gridview and I have added automatic refresh. My problem is that I`m unable to retain the selected value in dropdownlist after the refresh. It goes to the default settings in the dropdown. Please help.
Thanks a lot for replying..
part of my code goes this way....
page_load(...)
{
Refresh
if(!IsPostBack)
{
//calling my function which includes databind..
myfunction();
}
}
i tried the same code as you people suggested but its not working..
even now after refresh, the default values appear in dropdownlist

You probably need to implement something like this in your page_load handler:
if (IsPostback) return;
//here populate the dropdown

Let me guess your Page_Load:
protected void Page_Load(object sender, EventArgs e)
{
DataBindGridView(); // loads the datasource of the grid and calls gridView1.DataBind();
DataBindDropDown(); // loads the datasource of the dropdown and calls dropDown1.DataBind();
}
Do not reload all on every postback, just if !(IsPostBack):
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
DataBindGridView();
DataBindDropDown();
}
}
If you need to refresh your GridView don't use Page_Load but the appropriate event handler. If you use an ASP.NET Timer to reload your page periodically to refresh the grid, use it's Tick event.
protected void GridRefreshTimer_Tick(object sender, EventArgs e)
{
DataBindGridView();
}

Run the button event handler before page_load

I have a table with all the objects I have in my db. I load them in my Page_Load function. I have a text field and a button that when clicking the button, I want the handler of that click to put a new object with the name written in the text field in the db.
Now, I want that what happens after the click is that the page loads again with the new item in the table. The problem is that the button event handler is run after the Page_Load function.
A solution to this would be to use IsPostBack in the Page_Load or use the pre load function. A problem is that if I would have 3 different buttons, I would have to differ between them there instead of having 3 different convenient functions.
Any solutions that don't have this problem?
Code:
protected void Page_Load(object sender, EventArgs e)
{
if (Session["userId"] == null)
Response.Redirect("Login.aspx");
// LOAD DATA FROM DB
}
protected void CreateObject(object sender, EventArgs e)
{
// SAVE THE NEW OBJECT
}

Maybe you should try loading your data during PreRender instead of Load
protected void Page_Load(object sender, EventArgs e)
{
this.PreRender += Page_PreRender
if (Session["userId"] == null)
Response.Redirect("Login.aspx");
}
protected bool reloadNeeded {get; set;}
protected void CreateObject(object sender, EventArgs e)
{
// SAVE THE NEW OBJECT
reloadNeeded = true;
}
protected void Page_PreRender(object sender, EventArgs e)
{
if(reloadNeeded || !IsPostBack)
// LOAD DATA FROM DB
}

You can check the event target and do what you need then:
protected void Page_Load(object sender, EventArgs e)
{
if (IsPostBack)
{
string eventTarget = Page.Request.Params["__EVENTTARGET"];
if(whatever)
{
//do your logic here
}
}
}
Get control name in Page_Load event which make the post back

Use the Page_PreRenderComplete event to retrieve your table. That way your page will always have the most recent data available after all user events have fired.

Why don't you move what you have in the click event into a new method. Then call that method as the first line in your page load?

An old question but I faced the same problem in my C#/ASP.NET Website with master/content pages: a click on a link on the master page should change a query parameter for a gridview on the content page. As you stated the button click event is handled after Page_Load. But it is handled before Page_LoadComplete (see the information about ASP.NET Page Life Cycle), so you can change the page content there.
In my case I solved the problem by setting a session variable in the click event in the master page, getting this variable in the Page_LoadComplete event in the content page and doing databind based on that.
Master page:
<asp:LinkButton ID="Btn1" runat="server" OnCommand="LinkCommand" CommandArgument="1" >Action 1</asp:LinkButton>
<asp:LinkButton ID="Btn2" runat="server" OnCommand="LinkCommand" CommandArgument="2" >Action 2</asp:LinkButton>
protected void LinkCommand(object sender, CommandEventArgs e)
{
HttpContext.Current.Session["BindInfo", e.CommandArgument.ToString());
}
Content page:
protected void Page_LoadComplete(object sender, EventArgs e)
{
string BindInfo = HttpContext.Current.Session["BindInfo"].ToString();
YourBindDataFunction(BindInfo);
}

to avoid page refresh during button click event in asp.net

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack) // If page loads for first time
{
Session["update"] = Server.UrlEncode(System.DateTime.Now.ToString()); // Assign the Session["update"] with unique value
//=============== Page load code =========================
//============== End of Page load code ===================
}
}
protected void Button1_Click(object sender, EventArgs e)
{
if (Session["update"].ToString() == ViewState["update"].ToString()) // If page not Refreshed
{
//=============== On click event code =========================
Label1.Text = TextBox1.Text;
//lblDisplayAddedName.Text = txtName.Text;
//=============== End of On click event code ==================
// After the event/ method, again update the session
Session["update"] = Server.UrlEncode(System.DateTime.Now.ToString());
}
else // If Page Refreshed
{
// Do nothing
}
}
protected override void OnPreRender(EventArgs e)
{
ViewState["update"] = Session["update"];
}
}
This is not working for high resolution gradient background.

Consider wrapping your button and the label in an updatepanel control, which uses AJAX to refresh their contents.
The rest of the page will not be reloaded and the action will not affect the browser navigation.
See this page on how an updatepanel control works.

Since you are handling the button click event in server side there has to be a postback to handle it.
If you do not want a post back to happen change the event handling to "client click"

//Heinzi code worked for me just made a small change in OnPreRender event, assign the ViewsState value when its not post back
protected override void OnPreRender(EventArgs e)
{
if (!IsPostBack)
{
ViewState["update"] = Session["update"];
}
}

get submit button id

Inside asp.net form I have few dynamically generated buttons, all of this buttons submit a form, is there a way to get which button was submit the form in page load event?

The sender argument to the handler contains a reference to the control which raised the event.
private void MyClickEventHandler(object sender, EventArgs e)
{
Button theButton = (Button)sender;
...
}
Edit: Wait, in the Load event? That's a little tricker. One thing I can think of is this: The Request's Form collection will contain a key/value for the submitting button, but not for the others. So you can do something like:
protected void Page_Load(object sender, EventArgs e)
{
Button theButton = null;
if (Request.Form.AllKeys.Contains("button1"))
theButton = button1;
else if (Request.Form.AllKeys.Contains("button2"))
theButton = button2;
...
}
Not very elegant, but you get the idea..

protected void Page_Load(object sender, EventArgs e) {
string id = "";
foreach (string key in Request.Params.AllKeys) {
if (!String.IsNullOrEmpty(Request.Params[key]) && Request.Params[key].Equals("Click"))
id = key;
}
if (!String.IsNullOrEmpty(id)) {
Control myControl = FindControl(id);
// Some code with myControl
}
}

This won't work if your code is inside a user control:
Request.Form.AllKeys.Contains("btnSave") ...
Instead you can try this:
if (Request.Form.AllKeys.Where(p => p.Contains("btnSave")).Count() > 0)
{
// btnSave was clicked, your logic here
}

You could try:
if (this.Page.Request.Form[this.btnSave.ClientID.Replace("_", "$")] != null) {
}

please try this code in page load event
string eventtriggeredCategory = Request.Form["ctl00$ContentPlaceHolder1$ddlCategory"];
if eventtriggeredCategory is returning any value its fired the event of ddlCategory
this is works fine for me
Thanks
Jidhu

Request.Form["__EVENTTARGET"] will give you the button that fired the postback

Use CommandArgument property to determine which button submits the form.
Edit : I just realized, you said you need this at PageLoad, this works only for Click server side event, not for PageLoad.