Perhaps I'm making a faulty assumption here, but this has me stumped.
I've got to set up two identical repeaters in two different places in the same control. I want to avoid changing the names of controls so I can use the same functions on the front end (and actually, if there's a better way to have two identical repeaters in two different places other than a straight copy and paste, that'd be great). But for simplicity's sake, I've broken down the two as follows:
<asp:Repeater ID="rptTest" runat="server">
<ItemTemplate>
<asp:UpdatePanel runat="server" ID="updTestPanel">
<ContentTemplate>
<asp:TextBox ID="txtTest" runat="server" />
</ContentTemplate>
</asp:UpdatePanel>
<asp:TextBox ID="txtTest2" runat="server" />
</ItemTemplate>
</asp:Repeater>
<asp:Repeater ID="rptTest2" runat="server">
<ItemTemplate>
<asp:UpdatePanel runat="server" ID="updTestPanel">
<ContentTemplate>
<asp:TextBox ID="txtTest" runat="server" />
</ContentTemplate>
</asp:UpdatePanel>
<asp:TextBox ID="txtTest2" runat="server" />
</ItemTemplate>
</asp:Repeater>
Here's the thing: txtTest2 is fine being repeated in both repeaters, but txtTest throws the following errors:
Error 4 'txtTest' is already declared as 'Protected WithEvents txtTest As System.Web.UI.WebControls.TextBox' in this class.
Error 5 'Private Overloads Function __BuildControltxtTest() As System.Web.UI.WebControls.TextBox' has multiple definitions with identical signatures.
Error 8 'txtTest' is already declared as 'Protected WithEvents txtTest As System.Web.UI.WebControls.TextBox' in this class.
Is there a way to do what I'm trying to do, or do I need to rethink how I'm calling in asynchronous data in the repeater?
Without knowing too much as to what you are trying to do, the approach you have will work - but you cannot have two controls with the same name on the page. They are all in 'page' scope, and hence will complain.
What I would suggest is to have the methods be different for each textbox inside the repeater, but have them call different methods. In those methods, you can just pass the texbox values to a centralized method which will actually do the work. This way, you don't have to repeat the code, all you are doing is making two different functions that are the pass-thrus to your centralized method..
If you have controls that are DataBound (Repeater, DataList, FormVeiw, etc.) and under the updatepanel, these controls will have page level scope. You have to give them unique IDs, as I don't think that there is another work around for this problem. If you notice these controls are available on the page, without using FindControl.
Related
I am making some changes to an internal application that has a Telerik RadGrid component on one .aspx page.
Each row in the RadGrid represents an order and there is a dropdown which allows setting the status of the order. Changing the status of the order updates a couple of other properties of the order which are displayed on that row.
Up until now, changing the order status has resulted in a complete page post back and re-render. I'm keen to change this to a partial post back using an UpdatePanel. I could wrap the status dropdown (a RadCombo) in an UpdatePanel which would take care of the actual database changes that are required (as per the code sample below), but then without updating the other properties on the RadGrid row, the updates are not presented to the user.
<telerik:RadGrid ID="OrdersGrid" runat="server" ...>
<MasterTableView DataKeyNames="OrderId" AllowMultiColumnSorting="false">
<NoRecordsTemplate ...></NoRecordsTemplate>
<Columns>
<telerik:GridBoundColumn ... />
...
<telerik:GridTemplateColumn HeaderText="Order Status" UniqueName="OrderStatus">
<ItemTemplate>
<asp:UpdatePanel runat="server">
<ContentTemplate>
<telerik:RadComboBox ID="RadOrderStatus" DataSourceID="OrderStatusDataSource" runat="server"
SelectedValue='<%# Bind("OrderStatus") %>' Skin="Metro" Width="180px" DataTextField="OrderStatus"
DataValueField="OrderStatus" AutoPostBack="True" EnableLoadOnDemand="False" OnSelectedIndexChanged="RadOrderStatus_SelectedIndexChanged">
</telerik:RadComboBox>
</ContentTemplate>
</asp:UpdatePanel>
</ItemTemplate>
</telerik:GridTemplateColumn>
</Columns>
<SortExpressions>...</SortExpressions>
</MasterTableView>
</telerik:RadGrid>
I'm wondering how I can use the UpdatePanel to effectively wrap the row of the RadGrid so that the entire row can be updated as opposed to just the cell that the dropdown is in. I've tried experimenting already with tag placement but I'm new to Telerik and therefore not very clued up.
At what level in the mark up can I place the UpdatePanel to get this to work as I'd like?
Or is there a Telerik way of doing this?
I could wrap the whole grid but if possible, I'd rather not have the whole grid update on each partial post back, the permitted operations are limited to the row level so I see a full grid update as wasteful.
You can't place an UpdatePanel around each row. For starters, there is no provision to do that (you can't do it with the standard GridView either). Then, if you manage to do that (e.g., override the Render event), you would get invalid markup because you can't have <div> elements inside the <table> and between the other <tr> nodes.
One note on the performance—the AJAX request will have the page go through its entire lifecycle on the server, so all code will be executed again and any time consuming operation will also be executed. The only difference between the AJAX and the full postback is what gets rendered and returned in the response, so you basically shave off network time only.
What you can do is the following:
wrap the entire grid. I would use RadAjaxPanel and RadAjaxLoadingPanel so you have a pretty loading indicator. Something like:
<telerik:RadAjaxLoadingPanel ID="RadAjaxLoadingPanel1" runat="server" Skin="Black"></telerik:RadAjaxLoadingPanel>
<telerik:RadAjaxPanel ID="RadAjaxPanel1" runat="server" LoadingPanelID="RadAjaxLoadingPanel1">
<telerik:RadGrid ID="RadGrid1" runat="server"></telerik:RadGrid>
</telerik:RadAjaxPanel>
OR, use client-side code and jQuery. The combo can call a WebService or a PageMethod that will return the data and you can use jQuery to traverse the DOM and update the other elements (textboxes, dropdowns, whatever you have). This is going to be more difficult.
I've been wondering to why you have to use FindControl to reference the checkbox in the Login1's LayoutTemplate. Example:
var login1CheckBox1 = (CheckBox)Login1.FindControl("CheckBox1");
I would expect to be able to do something along the lines of:
var login1CheckBox1 = Login1.LayoutTemplate.CheckBox1;
In the case of the Repeater below, it is obvious, because there can be n number of CheckBoxes.
But for the Login control, it doesn't seem to make sense. Why wouldn't this be implemented differently?
<asp:Login ID="Login1" runat="server">
<LayoutTemplate>
<asp:CheckBox ID="CheckBox1" runat="server" />
</LayoutTemplate>
</asp:Login>
<asp:Repeater ID="Repeater1" runat="server">
<ItemTemplate>
<asp:CheckBox ID="CheckBox1" runat="server" />
</ItemTemplate>
</asp:Repeater>
Does anyone have any light to shine on this?
A control added to a page via markup is defined in the designer partial class, generally, at design time.
A control added to a template is generally instantiated programmatically within the control's collection of controls.
Since the control added to the template does not exist at compile-time in the definition of that control, it would be rather impossible to achieve the syntax you're aiming for.
When creating a page in markup, we're using the IDE's facilities to generate a partial class. When defining a template in markup, we're simply setting the value of the ITemplate for that control.
I'm under the impression that a control in a nested UpdatePanel will cause the top level UpdatePanel to refresh (thus refreshing both UpdatePanels) because any events on that control act as an "implicit" trigger. Is that correct?
I've been trying to wire something like this up-
UserControl
Parent UpdatePanel
"Show" button
ASP:Panel
Dynamically added UserControls, each with UpdatePanels
When the Show button is clicked, the ASP:Panel becomes visible and starts adding UserControls to itself dynamically, based on some back-end logic.
Each of the dynamically added controls (henceforth: UserControls) have their own Atlas-enabled buttons and links, so they have UpdatePanels too. Currently when I click on a link in one of the UserControls, the entire contents of the ASP:Panel disappear, as if it's being re-rendered. All of my dynamically-added controls disappear, and none of their click events are caught in the debugger.
I'm assuming what's happening here is that controls that reside in nested update panels are causing the parent UpdatePanel to post back because they're firing "implicit" triggers. Is there a way for my UserControls to operate autonomously and not mess with the ASP:Panel that contains them?
If not, what strategy should I be pursuing here? If I have to re-render the entire ASP:Panel every time an event happens on one of the (possibly many) UserControls, that means I'll have to recreate the UserControls, which take a bit of effort to create. I'll also have to preserve some kind of view state to recreate them. I'm somewhat new to ASP.NET and that sounds intimidating. I'd rather never refresh the top leve UserControl and ASP:Panel if I can avoid it, and let each of the dynamically-added UserControls fire and handle their own events asynchronously.
EDIT: Instead of adding the controls dynamically, I added them to the markup(not a bad solution). So got rid of the controls disappearing problem, because now the controls are not added dynamically but instead exist in the markup. But still the parent UpdatePanel posting is a big performance hit, because all the UserControls are getting posted instead of one. How do I make only one UserControl postback? Also, I would like to know how to get rid of the problem of controls disappearing if added dynamically?
First off, keep in mind: UpdatePanels do not alter the lifecycle of a page.
All of the Control Tree (including the UpdatePanels) must be reconstructed just as with a Normal Postback Life-cycle.1 2 The UpdatePanels ensure that only a portion of the rendered (HTML) view is returned. Removing all UpdatePanels should result in the same behavior, except with a full postback. For instance, only the HTML representing a nested UpdatePanel (presumably because data changed) might be sent back in the XHR response.
To get "true" AJAX consider Page Methods. Alternatively, DevExpress (and perhaps Telerik and others?) offer their own form of "Callback Panels", which are similar to UpdatePanels, but can bypass parts of the life-cycle (and, as a result often do not support the ViewState model entirely or may introduce their own quirks).
While not understanding the above is the most likely reason for the controls "disappearing", here is my rule: Do Not Let [Nested] UpdatePanels Work "Automatically".
Edge cases with dynamic controls and nested UpdatePanels will be encountered. There might be a nice way to handle this, but I have failed on multiple different attempts.
Instead, for every update panel, run with:
UpdateMode="Conditional"
ChildrenAsTriggers="False"
With the "Conditional" UpdateMode, make sure to manually specify the Trigger control or call panel.Update() (although this hard-wires the Control) as required. Depending on needs ChildrenAsTriggers="True" might work as well. The big thing is that UpdateMode is not "Always" which is the default.
After switching to this approach, I have no problem -- well, almost none -- with nested UpdatePanels.
Happy coding!
1 If the page doesn't render correctly where Partial Rendering (in the ScriptManager) is disabled (e.g. all requests are full postbacks) then there is no reason to expect/believe it will work correctly with UpdatePanels.
2 There are times when it's warranted to "cheat" expensive recomputations in the control tree for controls that will not be re-rendered. However, I would consider these advanced cases that should only be done when performance analysis indicates there is a specific need.
I had a similar issue with a heavy ajax Gridview control, and a HTML page with multiple UpdatePanels, some nested, some not.
It took me over 3 weeks of trial and error, reading, testing, debugging and prototyping to finally resolve all the post backs and partial postbacks.
However I did notice a pattern, which worked for me.
Like the #user above's response, make sure your UpdatePanels are set Conditional and only specificy asp:PostBackTrigger on the final or decisive control that you want the page to do a full postback on. I always use asp:AsyncPostBackTrigger where ever possible.
So for example, if you're using UpdatePanels inside a GridView and you want a popup inside a cell of the gridview's row, then you need to use a nested UpdatePanel.
ie
<asp:TemplateField HeaderText="Actions & Communications">
<ItemTemplate>
<asp:UpdatePanel ID="upAction1" runat="server" UpdateMode="Conditional">
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btnActionOK" />
</Triggers>
<ContentTemplate>
...
...
<ajaxToolkit:ModalPopupExtender ID="ajaxMPE" runat="server"
BackgroundCssClass="modalBackground"
PopupControlID="upAction2"
TargetControlID="btnADDaction">
</ajaxToolkit:ModalPopupExtender>
<asp:UpdatePanel ID="upAction2" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:Panel ID="pnlACTION" runat="server" CssClass="pnlACTION">
<div id="divHDR">
<asp:Label ID="lblActionHdr" runat="server">** header **</asp:Label>
</div>
<div id="divBOD">
<table style="width: 98%; text-align:left">
<tr>
<td colspan="2">
Please enter action item:<br />
<asp:TextBox ID="txtAction" runat="server" ValidationGroup="vgAction" TextMode="MultiLine" Rows="3" Width="98%"></asp:TextBox>
<asp:RequiredFieldValidator ID="rfvAction" runat="server" ControlToValidate="txtAction" ValidationGroup="vgAction"
ErrorMessage="* Required" SetFocusOnError="True"></asp:RequiredFieldValidator></td>
</tr>
<tr>
<td colspan="2">
Select staff assigned to this task:<br />
<asp:DropDownList ID="ddlActionStaff" runat="server" AppendDataBoundItems="true" ValidationGroup="vgAction" />
<asp:RequiredFieldValidator ID="rfvStaff" runat="server" ControlToValidate="ddlActionStaff" InitialValue="0" ValidationGroup="vgAction"
ErrorMessage="* Required" SetFocusOnError="True" Width="98%"></asp:RequiredFieldValidator></td>
</tr>
<tr>
<td colspan="2" style="text-align: center">
<asp:Button ID="btnActionOK" runat="server" Text="OK" OnClick="btnActionOK_Click" ValidationGroup="vgAction" CausesValidation="false" />
<asp:Button ID="btnActionCANCEL" runat="server" Text="CANCEL" OnClick="btnActionCANCEL_Click" ValidationGroup="vgAction" CausesValidation="false" />
</td>
</tr>
</table>
</div>
</asp:Panel>
</ContentTemplate>
</asp:UpdatePanel>
</td>
</tr>
</table>
<asp:SqlDataSource ID="sdsTETactions" runat="server" ConnectionString="<%$ ConnectionStrings:ATCNTV1ConnectionString %>"
...
...
</asp:SqlDataSource>
</ContentTemplate>
</asp:UpdatePanel>
</ItemTemplate>
<ItemStyle HorizontalAlign="Center" />
</asp:TemplateField>
Notice a few things here:
The ModalPopupExtender does not refer to the Ok and Cancel buttons. This is because I want them to trigger a partial postback to the server (code-behind)
The nested UpdatePanel (upAction2) is purely to force a partial postback on that panel only (pnlAction)! Therefore this forces the data validation triggers to work and keep the panel open if the user does not provide data in the requiredfield validators
The main UpdatePanel (upAction1) controls the entire lot and keeps all postbacks held within that panel only and NOT affecting the gridview (not shown entirely).
There is a great article here, which explains it better.
I hope this helps someone
I have a massive viewstate hidden field that is causing my application to be unworkable. I have tried:
EnableViewState="false" on every control
EnableViewState="false" in page directive
Page.EnableViewState = false in Page_Init
<pages enableViewState="false" /> in web.config
The page causing the issue has a single GridView which I want to render once only, so I don't ever need the viewstate.
I examined the hidden field using this tool, and there is apparently hardly any info in it (since I disabled the property in every control probably). For some reason though, the page insists on including a hidden field that is thousands and thousands of lines long.
How can I get rid of this field (or reduce it to a usable size) for good?
Here is an exert from the offending GridView:
<asp:GridView ID="MyGrid" runat="server" AutoGenerateColumns="False"
EnableModelValidation="True" EnableViewState="False"
CssClass="my-report">
<Columns>
<asp:TemplateField>
<HeaderTemplate>
<span title='title' class="abbr">My ID</span>
</HeaderTemplate>
<ItemTemplate>
<%# Eval("my_id") %>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<HeaderTemplate>
<span title='title2' class="abbr">Second col heading</span>
</HeaderTemplate>
<ItemTemplate>
<asp:ListView ID="MyListView" runat="server" EnableViewState="False">
<LayoutTemplate>
<ul>
<asp:PlaceHolder runat="server" ID="itemPlaceHolder" EnableViewState="False" />
</ul>
</LayoutTemplate>
<ItemTemplate>
<li><%# Eval("field_2")%></li>
</ItemTemplate>
</asp:ListView>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
The hidden field you see on the page is not only for ViewState, it also contains the ControlState. There is no way to disable the control state so you'll need to find a way to live with it. How many items the grid is displaying?
As a last option you may consider compressing generated viewstate field.
Here you have an MSDN article explaining how ControlState works
If your GridView is non-interactive (that is, it doesn't contain any child controls that post back), then you can reduce the size of view state by waiting until the page's Render method is called to bind the grid:
Protected Overrides Sub Render(writer As HtmlTextWriter)
MyGrid.DataSource = ...
MyGrid.DataBind()
MyBase.Render(writer)
End Sub
In case anyone has a similar problem, it was occuring because I had a ListView inside each row of the grid. I replaced the ListView with a Repeater and the viewstate is no longer a problem.
Another option is to use Flesk.ViewState something.
It can put the viewstate on files, compress it, session, etc.
Like the others say, sometimes is inevitable in ASPNET to live with ViewState.
Thats why your best option is to move to MVC :)
So I am working on localization for a website, and I have ran into many scenarios where I need to output the localized string from the resource, such as in the following markup:
<cc1:TabPanel HeaderText="<%= Culture.Strings.labelImageA %>">
<HeaderTemplate>
<img id="ImageA" runat="server"/>
</HeaderTemplate>
<ContentTemplate>
<uc2:Charter ID="CharterA" runat="server" />
</ContentTemplate>
</cc1:TabPanel>
In the instance above, I am attempting to output form the resource Culture.Strings.labelImageA but am receiving a warning that
This is not a scriplet.Will be output as plain text
Is there an escape character I can use in the markup in order to allow this to pull from the resource file? Otherwise, I will have to jump through many hoops to set this property in the code behind.
What surely works is to use binding markup <%# %>. This, however, would probably require calling DataBind manually on your control.
I doubt there exists a simpler way.