On PostBack, from clicking on an ImageButton, it first hits
protected void Page_Load(object sender, EventArgs e)
Then it hits
protected void ImageButton_Click(object sender, EventArgs e)
My problem is that in my Page_Load it refreshes a ListBox before the selected items can be processed by ImageButton_Click.
Is there a way to tell what events are yet to be processed, so I can handle them?
Populate/databind your ListBox within Page_Load only on the first load, not after postback. Viewstate will maintain the items in your ListBox subsequently.
protected void Page_Load(object sender, EventArgs e) {
if(!IsPostBack) //if not postback
{
//populate your listbox
}
}
Here's a good read on the Page's Lifecycle, you'll understand the sequence/order of page/child-controls' events and their purposes.
http://msdn.microsoft.com/en-us/library/ms178472.aspx
Related
I use a gridview to display the search result. After clicking search button, the gridview will show page 1, but when I click page 2 link, the gridview disappeared and it was back when I click search button again and show page 2's content.
here is my code
<asp:GridView ID="searchresult" runat="server" AutoGenerateColumns="true" AllowPaging="true" OnRowDataBound="searchresult_RowDataBound" OnPageIndexChanging="searchresult_PageIndexChanging"
HeaderStyle-BackColor="#f9e4d0"
HeaderStyle-Height="20px"
Font-Size="11px"
AlternatingRowStyle-BackColor="#cfdfef"
Width="800px" style="text-align:left">
</asp:GridView>
and code behind
protected void search_Click(object sender, EventArgs e)
{
List<someclass> totalResult = new List<someclass>();
..... //some code to generate the datasource
searchresult.DataSource = totalResult;
searchresult.AllowPaging = true;
searchresult.DataBind();
}
protected void searchresult_RowDataBound(object sender, GridViewRowEventArgs e)
{
}
protected void searchresult_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
searchresult.PageIndex = e.NewPageIndex;
DataBind();
}
I have no idea why the page 2 won't show up until I click search button again. when I clicked the page 2 link, the page did postback but the RowDataBound event was not fired
You have to give your grid a datasource. It appears you are only doing this on search_Click, so your grid is only going to have data then. Try something like:
protected void search_Click(object sender, EventArgs e)
{
PopGrid();
}
protected void searchresult_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
searchresult.PageIndex = e.NewPageIndex;
PopGrid();
}
protected void PopGrid()
{
List<someclass> totalResult = new List<someclass>();
..... //some code to generate the datasource
searchresult.DataSource = totalResult;
searchresult.AllowPaging = true;
searchresult.DataBind();
}
searchresult_PageIndexChanging event handler will make that functionality work. However I recommend you use a gridview control inside a Panel with vertical scroll bar. My user love it and it is a lot faster moving up and down the gridview without defining any page index changing.
I hope it work for you.
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();
}
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);
}
I need help with figuring out why the buttons in a Gridview are not transferring to the designated pages when clicked.
I added a button (Button1) outside of the GridView, for which the Server.Transfer("Page2.aspx") will work, yet it won't work for the buttons in the GridView (it just renders a postback to the same page).
Does anyone know why the button click for the GridView will not go to Page2.aspx?
(I have Googled this question, and the answers that others received did not work for my program).
Some of the code:
protected void Page_Load(object sender, EventArgs e)
{
}
protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
{
if (e.CommandName.Equals("GoToPageTwo"))
{
int index = Convert.ToInt32(e.CommandArgument);
GridViewRow row = GridView1.Rows[index];
Server.Transfer("Page2.aspx");
}
}
protected void Button1_Click(object sender, EventArgs e)
{
Server.Transfer("Page2.aspx");
}
protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
}
I am using Visual Studio 2010, and I created a site (.aspx).
I have 2 radiobuttons, and a DropDownList.
I want to have an invisible dropdownlist and whenever I click on the one radiobutton then the downdownlist to appear!
I have added a code like this but nothing changes and I can't understand why!!
protected void RadioButton_CheckedChanged(object sender, EventArgs e)
{
if (RadioButton1.Checked == true)
DropDownList4.Visible = true;
else
DropDownList4.Visible = false;
}
protected void Page_Load(object sender, EventArgs e)
{
DropDownList4.Visible=false;
}
The only thing I am getting, is an invisible dropdownlist than never becomes visible!
Both of my radiobuttons have the same action "radiobutton_checkedchanged" ..
Thank you!
your code is ok , set AutoPostBack property of radiobutton to true
since RadioButton_CheckedChanged(object sender, EventArgs e) events occurs after page load
it will work no need for checking !IsPostBack
Modify your code as below:
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
DropDownList4.Visible=false;
}
}