Develop Reference

Sending data from a button inside a repeater control to code-behind

I've got a button inside a repeater control, and I need to send some identifying information from the button to the onClick event so I know which ID has been clicked. My asp.net code (in part) looks like this:
<asp:Repeater ID="ParentRepeater" runat="server" OnItemDataBound="ParentRepeater_ItemDataBound">
<ItemTemplate>
<div class="bevelBox"><h3><b><%#Eval("AlbumName") %> Photo Gallery</b></h3></div>
<asp:Repeater ID="PhotoRepeater" runat="server" onitemcommand="PhotoRepeater_ItemCommand" OnItemDataBound="PhotoRepeater_DataBinding">
<HeaderTemplate>
<div class="bevelBox">
<Table>
<tr>
<td style="width:160px"><h3>Concert Photo</h3></td>
<td style="width:535px"></td>
<td><asp:Button ID="btnAddPhoto" runat="server" OnClick="btnAddPhoto_Click" Text="Add Yours" CommandArgument='<%#Eval("AlbumID") %>' UseSubmitBehavior="false" /></td>
</tr>
</Table>
</div>
Someone told me I could use the CommandArgument command to get this data to the code-behind.
On the C# side, I have this:
protected void btnAddPhoto_Click(object sender, EventArgs e)
{
Button btn = (Button)sender;
string ggg = btn.CommandArgument.ToString();
mdlAddPhoto.Enabled = true;
mdlAddPhoto.Show();
}
I put a break point on the "string gggg" line, just to see what is being passed back. There's nothing indicating the <%#Eval("AlbumID") %> is being passed back.
Can anyone tell me how I can get this ID data passed back to the C# side?

call listview OnPagePropertiesChanging function from another function in c# asp.net

I have an aspx ListView control, a data pager for paging, paging is working fine. Now I have a dropdown to change page size and show the relevant records in listview. But dropdown not working properly.
I have total 14 records and when i go to 2nd page which has 4 records after that i change dropdown page size to 30 then it does not reflect listview and still showing same 4 records. It changes page number from 2nd to 1st only.
HTML:-
<asp:DropDownList ID="ddlCount" AutoPostBack="true" runat="server" CssClass="form-control"
SelectedIndexChanged="ddlCount_SelectedIndexChanged"> </asp:DropDownList>
<asp:ListView ID="lvParkingLots" runat="server" GroupPlaceholderID="grp" ItemPlaceholderID="item"
GroupItemCount="2" OnPagePropertiesChanging="lvPL_PagePropertiesChanging">
<LayoutTemplate>
<table class="table table-striped tblForm" id="gs">
<tr id="grp" runat="server">
</tr>
<tr class="pagination-listview">
<td></td>
<td style="float: right;">
<asp:DataPager ID="dp" runat="server" PagedControlID="lvParkingLots" PageSize="30">
<Fields>
<asp:NumericPagerField NextPageText="Next" PreviousPageText="Prev" />
</Fields>
</asp:DataPager>
</td>
</tr>
</table>
</LayoutTemplate>
C# function:-
protected void lvPL_PagePropertiesChanging(object sender, PagePropertiesChangingEventArgs e)
{
DataPager dp = (lvParkingLots.FindControl("dp") as DataPager);
dp.SetPageProperties(e.StartRowIndex, e.MaximumRows, false);
Binddata();
}
I have tried below code but not working..
protected void ddlCount_SelectedIndexChanged(object sender, EventArgs e)
{
Binddata();
}

The first argument to the event is of type object, here it should be the ListView, and the second argument will be PagePropertiesChangingEventArgs which is expecting StartRowIndex and MaximumRow, both are of type integer, so you can call that method like this:
int startRowIndex =2,MaximumRow=3;
lvPL_PagePropertiesChanging(lvSample, new PagePropertiesChangingEventArgs(startRowIndex , MaximumRow));
// where lvSample is the listview
In the case of the second example, you have to call the method like this:
ddlCount_SelectedIndexChanged(ddlCount, EventArgs.Empty);

Get the text of a label in a listview

I have a listview control which is populated with data from a database. I have used the label to display that data. Now I need to use the value of that label in some other place. I am trying to access the text value of the label control but it says
Object reference not set to an instance of an object.
But I do have value in the label.
<asp:ListView ID="msg_list" runat="server">
<ItemTemplate>
<table>
<tr class="myitem">
<td>
<asp:Label ID="reg_id_reply" runat="server" Text="helo" Visible="false" />
<asp:Label role="menuitem" ID="msg_lbl" runat="server" text='<%#Eval("msg")%>' /><i style=" color:Gray; " > from
<asp:Label ID="tme" runat="server" Text='<%#Eval("name")%>' />
<i> on </i>
<asp:Label ID="tmelbl" runat="server" Text='<%#Eval("tme")%>'/>
<a id="msg-reply" class="btn button" data-toggle="modal" data-target="#msg-rply" style="cursor:pointer;" ><i class="glyphicon glyphicon-share-alt white"> </i></a> </td>
<hr style=" margin-top:1px; margin-bottom:1px; " />
</tr>
</table>
<%--<hr style=" margin-top:1px; margin-bottom:1px; " />--%>
</ItemTemplate>
</asp:ListView>
This is how i tried to access the text of the label.Note that the code below is inside a button click event onClick of buttom.
Label mylbl = (Label)msg_list.FindControl("reg_id_reply");
string rid = mylbl.Text;

According to the description for Control.FindControl Method (String):
This method will find a control only if the control is directly contained by the specified container.
The direct container that your label is contained within is the ItemTemplate. Therefore you may need to build a recursive search for your label if you are starting with the listview. You could try the following code that is suggested from this MSDN page:
private Control FindControlRecursive(Control rootControl, string controlID)
{
if (rootControl.ID == controlID) return rootControl;
foreach (Control controlToSearch in rootControl.Controls)
{
Control controlToReturn = FindControlRecursive(controlToSearch, controlID);
if (controlToReturn != null) return controlToReturn;
}
return null;
}
However also note that the listview may change the id values of components in the item template. If you know the item index you want then you can use the method suggested in this post:
var theLabel = this.ChatListView.Items[<item_index>].FindControl("reg_id_reply") as Label;

Showing buttons if list view is empty

I have a list view which retrieves the data from sql data source. I am trying to make two buttons(Yes and No) and a label outside the list view visible only if the list view is not empty. The process is: a person enter the information into text boxes and click the button retrieve, if the entered data exists in the database, the list view shows certain information.
I have the following code:
protected void btnExistingRetrive_Click(object sender, EventArgs e)
{
if (lstExisting.Items.Count>0 )
{
lblIsITYou.Visible = true;
btnYes.Visible = true;
btnNo.Visible = true;
}
}
By default buttons and the label are not visible.
The problem is when i click on retrieve button it shows me the list view with the information but buttons a the label are still not visible. They became visible only when i double click the retrieve button. Please tell me what is my mistake?
Thank you

Use the ListView EmptyDataTemplate
<asp:ListView ID="ContactsListView"
DataSourceID="ContactsDataSource"
runat="server">
<LayoutTemplate>
<table runat="server" id="tblProducts">
<tr runat="server" id="itemPlaceholder" />
</table>
</LayoutTemplate>
<ItemTemplate>
<tr runat="server">
<td>
<asp:Label ID="FirstNameLabel" runat="Server" Text='<%#Eval("FirstName") %>' />
</td>
<td>
<asp:Label ID="LastNameLabel" runat="Server" Text='<%#Eval("LastName") %>' />
</td>
</tr>
</ItemTemplate>
<EmptyDataTemplate>
<table class="emptyTable" cellpadding="5" cellspacing="5">
<tr>
<td>
<asp:Image ID="NoDataImage"
ImageUrl="~/Images/NoDataImage.jpg"
runat="server"/>
</td>
<td>
No records available.
</td>
</tr>
</table>
</EmptyDataTemplate>
</asp:ListView>

do you bind listview before checking the items count?

Do this on postback instead of in the event.
In your Page_Load do something like this:
protected void Page_Load(object sender, EventArgs e)
{
bool visible = (lstExisting.Items.Count > 0); // assuming it's never null
lblIsITYou.Visible = visible;
btnYes.Visible = visible;
btnNo.Visible = visible;
}
If the above creates complications then do as I said first with postback:
protected void Page_Load(object sender, EventArgs e)
{
if (IsPostBack)
{
bool visible = (lstExisting.Items.Count > 0); // assuming it's never null
lblIsITYou.Visible = visible;
btnYes.Visible = visible;
btnNo.Visible = visible;
}
}

repeater databinding , with manipulation of certain data on every item binded

in a repeater, i want to do a function on every item bounded, example
<asp:Repeater runat="server" ID="rptArticleContent"
OnItemDataBound="rptArticleContent_ItemDataBound">
<ItemTemplate>
<tr>
<td width="365" valign="top" align="left" class="bodyContent" bgcolor="#FFFFFF">
<div>
<h2 class="h2">
<asp:Label runat="server" ID="dsds"> <%#Eval("Title") %></asp:Label>
</h2>
<div class="article-body">
<div class="Article-image">
<%#Eval("Image") %>
</div>
<%#Eval("Description") %>
</div>
<asp:Literal runat="server" ID="litArticleSource" Text='<%#Eval("Source") %>'>
</asp:Literal>
</td>
</tr>
</ItemTemplate>
</asp:Repeater>
in code behind i want to do some manipulation on the data inside the Literal
protected void rptArticleContent_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
Literal litArticleSource = rptArticleContent.FindControl
("litArticleSource") as Literal;
string ArticleSourcesR = litArticleSource.Text;
}
ArticleSourcesR still gives null, somes told me that when catching the controle with rptArticleContent.FindControl i should add something so it would be applied on every item bounded, what is that missing clue.?? what should be added?

You don't want to use rptArticleContent in the function, rather e.Item which will return the current repeater item instance.