I have a custom pager control and a GridView inside an update panel on my page in my system.
It normally works fine but a few times a week there will be an error in the logs where the PageIndex of the GridView is reset to 0.
The paging works like so.
private void PageBackward(Object sender, EventArgs e)
{
boundGridView.PageIndex = boundGridView.PageIndex - 1;
boundGridView.DataBind();
}
private void PageForward(Object sender, EventArgs e)
{
boundGridView.PageIndex = boundGridView.PageIndex + 1;
boundGridView.DataBind();
}
Simple right?
When this error occurs the users are just using the system normally.
We are in a clustered environment but all the GridView data should be stored in ViewState.
I'm considering just putting the PageIndex in the Session but really I shouldn't have to.
What causes this?
Related
I have a DropDownList and a CheckBox on my web form. After the DropDownList is clicked and this event is posted back to the server. DropDownList_SelectedIndexChanged event is called on the server side. Inside that event handler, I have CheckBox.Checked = true, But I couldn't make the page on the client side to reflect this change (CheckBox.Checked = true). How do I achieve this? Or am I in the wrong direction to use the DropDownList's event handler to update the CheckBox because the page firstly reloads and then DropDownList_SelectedIndexChanged is called?
Page load method:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
this.DropDownList1.Items.Clear();
AddItemsToDropDownList();
}
}
DropDownList selected index changed event handler:
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
var selected = this.DropDownList1.SelectedItem.Text;
CheckBox checkBox = GetCheckBoxToBeSetByText(selected);
checkBox.Checked = true;
}
OK. Found the issue. Actually there is nothing wrong with the code in my original post. But to make a smallest sample when I posted, I removed some "extra" code. The below is the "complete" code (OK, fine, I still removed some code). As you can see, I put the CheckBox into a static Dictionary. Each time the SelectedIndexChanged event handler is called, it's modifying the CheckBox in that static Dictionary, which means it's modifying the CheckBox object created from the last session? (still not clear here) Looks like each time when a postback message is received, a new set of CheckBox objects are created. Bear with me if this is known to everybody here already because I only have two days of experience on this web development thing up to today.
private static Dictionary<Environment, CheckBox> EnvironmentsCheckBoxes;
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
EnvironmentsCheckBoxes = new Dictionary<Environment,CheckBox>();
EnvironmentsCheckBoxes.Add(Environment.Dev1, this.Dev1_CheckBox);
EnvironmentsCheckBoxes.Add(Environment.Dev2, this.Dev2_CheckBox);
EnvironmentsCheckBoxes.Add(Environment.QA, this.QA_CheckBox);
EnvironmentsCheckBoxes.Add(Environment.QA2, this.QA2_CheckBox);
EnvironmentsCheckBoxes.Add(Environment.Demo, this.Demo_CheckBox);
EnvironmentsCheckBoxes.Add(Environment.Prod, this.Prod_CheckBox);
EnvironmentsCheckBoxes.Add(Environment.UAT, this.UAT_CheckBox);
}
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
var selected = this.DropDownList1.SelectedItem.Text;
if (selected == "Dev1")
{
EnvironmentsCheckBoxes[Environment.Dev1].Checked = true;
}
else if (selected == "Dev2")
{
...
}
...
}
In .NET i have a gridview which has to display on the mainpage with default settings. So i put it in pageload code. In the same page i have a "List" button; people choose date etc. and when they press the button gridview loads data from another stored procedure. I put that code under List button event. But after people press List button and gridview comes with the needed data, if they press something else (because of page refresh itself) gridview turns back to default settings.
How do i keep the gridview with wanted data?
protected void Page_Load(object sender, EventArgs e)
{
opsbelgegridview.DataSource = DB.OpsHavuzGetir();
opsbelgegridview.DataBind();
protected void listelebtn_Click(object sender, EventArgs e)
{
opsbelgegridview.DataSource = DB.OpsHavuzDetayListeleBtn(tarih1.ToString("yyyy-MM-dd"), tarih2.ToString("yyyy-MM-dd"), durumdd.SelectedItem.Text.ToString(), islemtipdd.SelectedItem.Text.ToString());
opsbelgegridview.DataBind();
You can use IsPostBack() and only load the initial grid on the first load of the page. Then if the grid data changes it will stay.
private void Page_Load()
{
if (!IsPostBack)
{
opsbelgegridview.DataSource = DB.OpsHavuzGetir();
opsbelgegridview.DataBind();
}
}
protected void Page_Load(object sender, EventArgs e)
{
if (ScriptManager.GetCurrent(this).IsInAsyncPostBack)
{
string id = ScriptManager.GetCurrent(Page).AsyncPostBackSourceElementID;
if (id == cboGroup.UniqueID)
{
foreach (ListItem i in lstTest.Items)
i.Selected = true;
}
}
}
This code runs when my cboGroup causes my UpdatePanel to refresh which has the lstTest in it and the data inside of it gets updated, but it does NOT select them all. How can I make it so when my UpdatePanel is finished refreshing all elements of the list box that it refreshed get selected?
[edit] I'm noticing now that at this point what's in the listbox is the previous values and not the new values I would need. So this seems to be before the listbox is filled with data (which is via a SqlDataSource) so it's probably overwriting this.
I was able to put my selection code in the list box's DataBound() event.
protected void lstTest_DataBound(object sender, EventArgs e)
{
SelectAllTest();
}
As I have problems loosing indexes after postbacks, is it beter to remember indexes or values in sessions?
Thanks.
I think if you simply make sure EnableViewState is not set to false for that specific control or on page level, then you will be able retain the indexes for selection done by user
I'd say store them in sessions, HOWEVER, do you make any selection stuff in the page load event, if so, have you checked so that it won't redo that population after a postback??
This could mess things up, this would set the time on every postback:
protected void Page_Load(object sender, EventArgs e)
{
Label1.Text = DateTime.Now.ToString();
}
This would however have your stuff remain intact in the viewstate and the time would only update if the page is loaded without a postback:
protected void Page_Load(object sender, EventArgs e)
{
if (Page.IsPostBack != true)
{
Label1.Text = DateTime.Now.ToString();
}
}
Time for my daily ASP.NET question.
One of my pages shows all of our customer information from a customer table. I want the user to choose whether to see all customer records, or select a specific record from a list. So, my webpage has two radio buttons (show all customers, show specific customer), a listbox (full of customer names), and a formview control. The problem I'm having is getting the formview to update when I change modes via radio buttons or listbox selection (see code below).
Can anyone provide me with some pointers on how to do what I'm trying to do?
protected void Page_Load(object sender, EventArgs e)
{
UpdatePage ();
}
protected void RadioButtonShowAll_CheckedChanged(object sender, EventArgs e)
{
}
protected void RadioButtonShowSelected_CheckedChanged(object sender, EventArgs e)
{
}
protected void DropDownListCustomers_SelectedIndexChanged(object sender, EventArgs e)
{
RadioButtonShowSelected.Checked = true;
UpdatePage ();
}
protected void UpdatePage ()
{
if (RadioButtonShowAll.Checked)
SqlDataSource1.SelectCommand = "SELECT * FROM [Customer] ORDER BY [Company]";
else
SqlDataSource1.SelectCommand = "SELECT * FROM [Customer] WHERE ([CustomerID] = #CustomerID) ORDER BY [Company]";
FormView1.DataBind();
}
First, you only have the SelectedIndexChanged event wired up... In that case, what happens when you change the drop down box is first, Page_Load() fires--which calls UpdatePage(). Then, the event fires, which calls UpdatePage() again. The second time probably doesn't do what you expect.
The fix is to only call UpdatePage() from Page_Load() the first time the page is loaded, but not from postbacks:
protected void Page_Load(object sender, EventArgs e)
{
if (!this.IsPostBack)
UpdatePage();
}
Your page has to be updated on Client side, for it to show the new data. You'll need to use Javascript or AJAX and have some variable that keeps track of the need to refresh your page, this way you can send a request to update the page to the server when the Formview needs updating.