Develop Reference

dropdown selected item and repose.redirect

I have two dropdownlist in my project and get the items from sql server. One of them show list of something (And I named it DropdownSoore) and another one show list of members of it (And I named it DropdownAye) that update when select an item from DropdownSoore. then when select an item from DropdownAye go to page of them by forwarding query string. I have no problem to updating DropdownAye but when I select item from it and redirect to page of it, the DropdownAye lose the selected item and show the first item (as default) and index to query string in url.
what should I do?
Excuse me about my grammer, I'm not English...
I set DropdownSoore:
<asp:DropDownList ID="DropDownListSoore" runat="server" class="nav-link btn btn-outline-secondary dropdown-toggle" aria-haspopup="true" aria-expanded="true" AutoPostBack="True"></asp:DropDownList>
for (int i = 0; i <= dt.Rows.Count - 1; i++)
{
string IdSoore = Convert.ToString(dt.Rows[i]["IdSoore"]);
string NameSoore = Convert.ToString(dt.Rows[i]["NameSoore"]);
DropDownListSoore.Items.Add(IdSoore + "." + NameSoore);
}
string forwardedIdSoore = Request.QueryString["IdSoore"];
if (forwardedIdSoore != null)
{
DropDownListSoore.Items.FindByValue(forwardedIdSoore);
}
And then set DropdownAye:
<asp:DropDownList ID="DropDownListAye" runat="server" class="nav-link btn btn-outline-secondary dropdown-toggle" aria-haspopup="true" aria-expanded="true" OnSelectedIndexChanged="DropDownListAye_SelectedIndexChanged" AutoPostBack="True"></asp:DropDownList>
DropDownListAye.Items.Clear();
for (int i = 0; i <= dt1.Rows.Count - 1; i++)
{
DropDownListAye.Items.Add(Convert.ToString(dt1.Rows[i]["NumberAye"]));
}
int iSelectedAye = Convert.ToInt32(DropDownListAye.SelectedIndex) + 1;
string SelectedAye = Convert.ToString(dt1.Rows[iSelectedAye]["IdAye"]);
Session["SSelectedAye"] = SelectedAye;
string forwardedIdAye = Request.QueryString["IdAye"];
if (forwardedIdSoore != null)
{
DropDownListSoore.Items.FindByValue(forwardedIdAye);
}
in page_Load. and dont have problem to update DopdownAye but when I used it to redirect always get IdAye=1 in url and show the first item of DropdownAye ...:
protected void DropDownListAye_SelectedIndexChanged(object sender, EventArgs e)
{
int SelectedAye = Convert.ToInt32(Session["SSelectedAye"]);
int SelectedSoore = Convert.ToInt32(DropDownListSoore.SelectedIndex) + 1;
string forward = "~/contentAye.aspx?IdSoore=" + SelectedSoore + "&IdAye=" + SelectedAye;
Response.Redirect(forward);
}
I try !IsPostBack but dont have utility too.
I do all thing I think and i dont know what shoild i do.

And where are you loading up these infomration?
Remember, page load ALWAYS fires and triggers for each post-back, for each button click, and any OTHER event on the page that calls code behind.
What does the above really mean?
Well, it means that you need to ONLY ONE TIME load up the drop downs, the gridview(s), or whatever else you have.
So, for the last 200+ web pages I have built, I ALWAYS have this code stub in the page load event:
so this markup:
<h3>Select Hotel</h3>
<asp:DropDownList ID="DropDownList1" runat="server"
DataValueField="ID"
DataTextField="HotelName" Width="356px">
</asp:DropDownList>
<br />
<br />
<asp:Button ID="Button1" runat="server"
Text="Show/get/display drop selection" OnClick="Button1_Click"
CssClass="btn" />
<br />
<h3>Selected result</h3>
<asp:Label ID="Label1" runat="server" Text=""></asp:Label>
and code behind:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
// load up data, controls etc.
string strSQL =
"SELECT ID, HotelName FROM tblHotelsA ORDER BY HotelName";
DataTable dt = General.MyRst(strSQL);
DropDownList1.DataSource = dt;
DropDownList1.DataBind();
DropDownList1.Items.Insert(0, new ListItem("Please Select Hotel", ""));
}
}
protected void Button1_Click(object sender, EventArgs e)
{
string sResault =
$#"dropdown list value (pkid) = {DropDownList1.SelectedItem.Value}
<br/>
Dropdown list Text (Hotel) = {DropDownList1.SelectedItem.Text}";
Label1.Text = sResault;
}
and the result:
SUPER important:
If I leave out the !IsPostBack test in page load, then for EVERY button click, the dropdown list re-load code will trigger, and runs BEFORE your button stubb, or post back. As a result, I will see/find/get no valid value from the drop down list, since page load ALWAYS runs before the given code stub, and thus if page load "every time" re-loads the data, then it will blow out the choosen value in the drop down list.
So, loading up of grids, data, dropdowns etc. can ONLY occur one time in page load, since page load ALWAYS runs before each button or event code stub you have behind.
If you thus only load up the controls and dropdowns on the first REAL page load, then the values the user selects in those dropdowns should work, but only will work if you ALWAYS include that all important if (!IsPostBack) code stub in your page load event.
Now, of course in place of that button to loadup + display the dropdown list into that label?
Well, of course that button click may well (like often) jump or navigate to another page. So, in place of that code to fill out the selected value(s) into that lable, we could pass the selected value to the next page. And how to do that? Well, you can use session(), you can use parmaters in the URL, or you can even use a post-back URL, and then the WHOLE previous page becomes available (Page.Previous), which then in theory allows you to grab ANY and ALL values from the previous page.
but, say we choose session() to pass the value, then this:
Session["HotelPK"] = DropDownList1.SelectedItem.Value;
Response.Redirect("GridFun3.aspx");

Datagrid ItemCommand event not firing

I am still a novice with asp.net, so I'm sure there are better ways to do some of this...
I want to allow a user to enter a date, and then execute an SQL query against a database to return all records matching that date. I want to display those records, and allow the user to select one for additional processing. It seemed like the DataGrid with a column of Pushbuttons was a good choice. In fact, I've done this before, but it those cases there was no user interaction involved. The page just ran a fixed SQL query. With what I'm doing now, the data is displayed as I want, but the Pushbuttons aren't working...the ItemCommand event doesn't fire.
I've read a lot of threads about the ItemCommand event not firing, but I still can't get this to work. My understanding is that I need to bind the DataGrid while not in a Postback, and I think my code does that. When I debug the Page_Load event, I can see that the code inside if (!IsPostBack){} is running, and the session variables have the expected data.
On the page that hosts the DataGrid, I have a 'Find' button that executes a SQL query against a database. The query uses a date entered into the textbox that is on that page. In the 'Find' button click event, I store the results of the query (a DataTable) in a session variable, then do a Redirect to re-load the page.
Once the page reloads, the session variables contain my expected data and the data is displayed in the DataGrid, along with the Pushbuttons. When I click any of the buttons in the DataGrid, the contents of the DataGrid disappear and the ItemCommand event does not fire.
Here's the definition of the DataGrid (updated to include the button):
<asp:Panel runat="server" ID="pnlSelect" HorizontalAlign="Left" Visible="true" style="margin-top:10px" >
Please select a participant.
<asp:DataGrid runat="server" ID="grdItems" AutoGenerateColumns="true" BorderColor="black" BorderWidth="1" CellPadding="3" style="margin-left:2px; margin-top:6px" OnItemCommand="grdSelect_ItemCommand" >
<Columns>
<asp:ButtonColumn HeaderStyle-HorizontalAlign="Center" ButtonType="PushButton" Text="Select" HeaderText="Select" CommandName="Select" >
<ItemStyle Width="60px" HorizontalAlign="Center"/>
</asp:ButtonColumn>
</Columns>
</asp:DataGrid>
</asp:Panel>
Here's the Page Load code (unneeded code-behind stuff is commented out):
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
if (Session["y"] != null)
{
txtFind.Text = Session["x"].ToString();
DataTable table = Session["y"] as DataTable;
Session.Remove("x");
Session.Remove("y");
if (table != null)
{
/*
ButtonColumn buttonColumn = new ButtonColumn
{
HeaderText = "Select",
Text = "Select",
CommandName = "Select",
ButtonType = ButtonColumnType.PushButton,
};
grdItems.Columns.Add(buttonColumn);
foreach (DataColumn c in table.Columns)
{
BoundColumn column = new BoundColumn
{
HeaderText = c.Caption,
DataField = c.Caption,
ReadOnly = true
};
grdItems.Columns.Add(column);
}
*/
grdItems.DataSource = table;
grdItems.DataBind();
}
}
}
}
Here's the relevant 'Find' button event code. I can't post the details of the sql query text, but that part does work and the DataTable does contain the expected data:
DataTable table = DatabaseHelper.FindBySQL(sqlText);
if (table != null && table.Rows.Count > 0)
{
Session["x"] = searchtext;
Session["y"] = table;
Response.Redirect(Request.RawUrl, true);
}
And this the ItemCommand event. I place a breakpoint on the first line, and the debugger never hits it.
protected void grdItems_ItemCommand(object source, DataGridCommandEventArgs e)
{
string item = "";
switch (e.CommandName.ToLower())
{
case "select":
item = e.Item.Cells[1].Text.Trim();
//todo: handle the selected data
break;
}
}
Thanks for any thoughts.
Don

Can't update using FindControl

I have a TextBox within my EditItemTemplate in my listview_car:
<EditItemTemplate>
<asp:TextBox ID="txt1" runat="server" Text='<%# Bind("photo1") %>' Visibile="true">
</asp:TextBox>
</EditItemTemplate>
Now in the code I have this in my ItemUpdating event:
protected void listview_car_ItemUpdating(object sender, ListViewUpdateEventArgs e)
{
var txt1 = listview_car.Items[0].FindControl("txt1") as TextBox;
txt1.Text = "newImage";
}
Now I have debugged it and the value that is showing from my DB is correct, then when I set it from the code using txt1.Text = "newImage"; it shows it has updated the textbox in the Auto's however it does not update in the DB, but the strange thing is when I type in the textbox and click the edit button it updates but doesn't update when I set the string in the code?
Does anyone know what I am doing wrong?

When ItemUpdating() is called all values were already collected in the NewValues collection. To modify any of values you should modify e.NewValues
protected void listview_car_ItemUpdating(object sender, ListViewUpdateEventArgs e)
{
e.NewValues["key"] = "newImage";
}
where "key" is a name of the key (not a name of the control) which is usually a column name. You could also use an index 0,1,2...

In listview_car_ItemUpdating, first update the database, then call whatever method you used to bind your controls to the database when the page first loaded. This will retrieve the new value of photo1 from the database and bind it to txt1.

Problem with DetailsView events

I have a list with button links when a button list is clicked this event is triggered:
protected void DetailsView1_ItemCommand(object sender, DetailsViewCommandEventArgs e)
{
DetailsView dv = (DetailsView)sender;
LinkButton linkbtn = (LinkButton)dv.FindControl("LinkButton3");
string threadID = e.CommandArgument.ToString();
string threadName = linkbtn.Text;
Server.Transfer("~/AnswerQuestion.aspx?x=" + threadID+"&question=" + threadName + "&time=" + DateTime.Now);
}
Mark up of the LinkButton.
<ItemTemplate >
<asp:LinkButton ID="LinkButton3" runat="server" Text=<%# Eval("ThreadTitle") %> CommandName="Select" CommandArgument=<%# Eval("ThreadsID") %>>LinkButton</asp:LinkButton>
</ItemTemplate>
The problem is that I allowed paging too..so the Detailsview1_ItemCommand is triggered when a certain page is clicked (e.g. if we are on page 1 and page 2 clicked, then the event is triggered)..
I want to prevent this by wrapping the Server.Transfer statement and make a condition that states whether it was the buttonLink that was clicked and not the pager...
(I cant cast sender..cause I get the DetailsView)
Is it possible..

You have specify a CommandName for LinkButton so why you don't use it?
if(e.CommandName == "Select")
{
//Do something
}
By the way if this LinkButton doesn't perform any server action except transferring onto another page maybe would be better to use simple anchor tag here.

SharePoint - Passing Dataview Row Arguments to a C# function from ASP.net button

I've done this with a asp.net Gridview. but does anybody have any examples on how to pass row information from an asp.net button in SharePoint Dataview rows to an inline C# function?
the button Repeats as follows:
<asp:Button runat="server" Text="Delete" id="Delete{#ID}" OnClick="DeleteDoc()"/>
My function looks like this:
void DeleteDoc(object sender, EventArgs e) { }
}
I tried adding another parameter but get:
No overload for 'DeleteDoc' matches delegate 'System.EventHandler'

Try to change your method access modifier to protected and OnClick="DeleteDoc()" to OnClick="DeleteDoc".
Also i didn't managed to make it work with id="Delete{#ID}" so try without that to.
This worked on my test case
<asp:Button runat="server" Text="Delete"
OnClick="DeleteDoc"
CommandArgument='<%# Eval("ID")%>'/>
and
protected void DeleteDoc(object sender, EventArgs e)
{
Button b = sender as Button;
YourDeleteDocumentHelperMethod(b.CommandArgument);
}