Custom Templated Control - To Modify Where Databound Data Is Output To?
Aug 31, 2010
Basically, I have a custom templated control with a custom data container class. When a developer adds an instance of my control to a page, they can define the controls in the LayoutTemplate however they like, as follows:
<ml:MyControl id="MyControl1" runat="server">
<LayoutTemplate>
<span><%#Container.ErrorMessage%></span>[code]...
I would like my control to automatically move the "ml_errormessage" (databound content from Container.ErrorMessage - hard coded token in the property) to be a class of its containing element to make it easier for jQuery to use a selector to find the element and dynamically insert the error message client side. More importantly, I would like it moved out of the way so the class name doesn't get replaced by the content and jQuery can find it as many times as it needs to during the page lifecycle. In other words, I would like the output to look like this without the developer changing the input template or resort to using custom controls in the template:
<span id="MyControl1"><span>
<span class="ml_errormessage"></span>
</span></span>
I would like to move the value using the controls collection rather than resorting to string parsing of the output, if possible. However, when I interrogate the collection in an override of OnPreRender, the control in the template looks like this in the debugger:
{System.Web.UI.DataBoundLiteralControl}
System.Web.UI.DataBoundLiteralControl: {System.Web.UI.DataBoundLiteralControl} [code]...
As you can see the "ml_errormessage" value is nowhere to be found. Upon analysis of the DataBind event of the Control class using Reflector, I see that it delegates the binding behavior to each control. In other words, each control handles its own databinding. However, since I have no way of knowing in advance what control types will be in the template, how can this change be done?
Note: an acceptable alternative would be to add a new HtmlGenericControl (span) in the exact spot where the "ml_errormessage" is and add it as a class to this new control.On a side note, is there an easy way to get the control's output to indent for easy reading during debugging?
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Similar Messages:
Nov 11, 2010
I am fairly new to asp.net programming. I found this custom control that uses ajax to update the contents of the control and it is working perfectly. However, I need to access some of the asp.net labels and images in the databound event so I can set their values/properties appropriately, and am not sure how to go about adding additional code or accessing these in my custom control (I have been googling endlessly with no results). My code for the custom control is below.
Imports System
Imports System.Text
Imports System.IO
Imports System.Collections
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports Microsoft.VisualBasic
Namespace myControls
Public Class AjaxDivView
Inherits CompositeDataBoundControl
Implements ICallbackEventHandler
Private _itemTemplate As ITemplate
''' <summary>
''' The ItemTemplate is used to format each item from the data source.
''' </summary>
<TemplateContainer(GetType(DivViewItem))> _
<PersistenceMode(PersistenceMode.InnerProperty)> _
Public Property ItemTemplate() As ITemplate
Get
Return _itemTemplate
End Get
Set(ByVal value As ITemplate)
_itemTemplate = value
End Set
End Property
''' <summary>
''' Register Javascript
''' </summary>
Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)
'Register Refresh Function
Dim eRef As String = Page.ClientScript.GetCallbackEventReference(Me, Nothing, "AjaxDivView_Result", "'" & Me.ClientID & "'", "AjaxDivView_Error", False)
Dim refreshFunc As String = "function AjaxDivView_Refresh() {" & eRef & "}"
Page.ClientScript.RegisterClientScriptBlock(Me.GetType(), Me.UniqueID, refreshFunc, True)
MyBase.OnPreRender(e)
End Sub
''' <summary>
''' Iterate through the data items and instantiate each data item in a template.
''' </summary>
Protected Overloads Overrides Function CreateChildControls(ByVal dataSource As System.Collections.IEnumerable, ByVal dataBinding As Boolean) As Integer
Dim counter As Integer = 0
For Each dataItem As Object In dataSource
Dim contentItem As New DivViewItem(dataItem, counter)
_itemTemplate.InstantiateIn(contentItem)
Controls.Add(contentItem)
counter = counter + 1
Next
DataBind(False)
Return counter
End Function
''' <summary>
''' Render this control's contents in a Ul tag
''' </summary>
Protected Overrides ReadOnly Property TagKey() As System.Web.UI.HtmlTextWriterTag
Get
Return HtmlTextWriterTag.Div
End Get
End Property
''' <summary>
''' Render my contents to a string and send the result back to the client
''' </summary>
Public Function GetCallbackResult() As String Implements System.Web.UI.ICallbackEventHandler.GetCallbackResult
Dim builder As New StringBuilder()
Dim sWriter As New StringWriter(builder)
Dim hWriter As New HtmlTextWriter(sWriter)
Me.RenderContents(hWriter)
Return builder.ToString()
End Function
''' <summary>
''' Whenever I get called through AJAX, rebind my data.
''' </summary>
Public Sub RaiseCallbackEvent(ByVal eventArgument As String) Implements System.Web.UI.ICallbackEventHandler.RaiseCallbackEvent
Me.DataBind()
End Sub
Public Class DivViewItem
Inherits WebControl
Implements IDataItemContainer
Private _dataItem As Object
Private _index As Integer
Public ReadOnly Property DataItem() As Object Implements System.Web.UI.IDataItemContainer.DataItem
Get
Return _dataItem
End Get
End Property
Public ReadOnly Property DataItemIndex() As Integer Implements System.Web.UI.IDataItemContainer.DataItemIndex
Get
Return _index
End Get
End Property
Public ReadOnly Property DisplayIndex() As Integer Implements System.Web.UI.IDataItemContainer.DisplayIndex
Get
Return _index
End Get
End Property
Protected Overrides ReadOnly Property TagKey() As System.Web.UI.HtmlTextWriterTag
Get
Return HtmlTextWriterTag.Div
End Get
End Property
Public Sub New(ByVal dataItem As Object, ByVal index As Integer)
_dataItem = dataItem
_index = index
End Sub
End Class
End Class
End Namespace
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Sep 29, 2010
Context
I'm putting together a templated, databound control. Presently it works with the following syntax...
<cc:ItemChooserControl ID="ItemChooser" runat="server">
<TitleTemplate>
<h4><%# DataBinder.Eval(Container.DataItem, "DisplayName") %></h4>
</TitleTemplate>
</cc:ItemChooserControl>
Problem
What I would like though is that the shorter, simpler Eval would work instead.
<h4><%# Eval("DisplayName") %></h4>
What I get however when using straight Eval is an error:
Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control.
Code
I'm databinding to a custom HtmlTableCell...
public class TitleTemplateTableCell: HtmlTableCell, INamingContainer
{
private object m_DataItem;
public virtual object DataItem
{
get { return m_DataItem; }
set { m_DataItem = value; }
}
}
With the following custom DataBind (non-related code removed)...
foreach (object dataItem in dataSource) {
TitleTemplateTableCell title = new TitleTemplateTableCell();
TitleTemplate.InstantiateIn(title); // TitleTemplate is the template property
title.DataItem = dataItem;
title.DataBind();
}
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Apr 5, 2010
I dont want to use asp.net's TreeView control. I want to create a custom template databound control with multi template support like -
<asp:MtNavigationControl>
<ItemTemplate>
...
...
</ItemTemplate>
<SelectedItemTemplate>
...
...
</SelectedItemTemplate>
<ParentItemTemplate>
...
...
</ParentSelectedItemTemplate>
<SelectedParentItemTemplate>
...
...
</SelectedParentSelectedItemTemplate>
</asp:MtNavigationControl>
My data is like -
class Employee
{
string EmployeeName
List<Employee> Employees
}
Does anyone know how to accomplish it?
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Apr 13, 2010
I am trying to develop a very simple templated custom server control that resembles GridView. Basically, I want the control to be added in the .aspx page like this:
[Code]....
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Mar 22, 2011
I am trying to build a custom composite control, which allows me to add custom content to each child control. It's a similar concept to what you have with a GridView and TemplateColumn. The markup used to place the control on the page would end up being something like this:
[Code]....
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[Code]....
I have tried to follow examples on MSDN and other forums but I can't make this work. I think I'm missing the code to render the contents of the template, but I don't know how to hook that up.
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Aug 11, 2010
I have a templated user control with single instance template attribute. It works great for everything except the following scenario:
[Code]....
The folder selector uses a tree view that allows people to select a folder, its FolderSelected event works perfectly and the file selector updates with the files. The file selector has a repeater that lists the files in the selected directory. It has a linkbutton for each of the files so that the user can select a file. The problem is that the ItemCommand event of the repeater doesn't fire when the file name is clicked on. The page performs the async postback like it should, but in debug, the method to handle the itemcommand event is never hit. On the same user control to select files there is a button that the user can add files to the folder. When it is clicked, the event DOES fire and the file is added and the control refreshes in the update panel, everything perfect. It seems that because the linkbutton is already in a templated control (which is in a user control, in a templated control), the event isn't firing correctly. I am confused as to why this should be a problem, especially since all the other events (even the custom ones) fire as long as they aren't in another templated control. Since the code is complicated, I didn't want to post it all here.
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Mar 22, 2010
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Sep 29, 2010
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Feb 26, 2010
I am writing an ASP.NET custom control.In my custom control code, I find a PlaceHolder control in the page like so:this.myPlaceholder = Page.FindControl("placeholder1") as PlaceHolder Then, I render the placeholder as the output of the custom control:
protected override void Render(HtmlTextWriter output)
if (this.myPlaceholder != null)
this.myPlaceholder.RenderControl(output);
However, this causes the placeholder to be rendered in two places - in the custom control output (good) and in the original location in the page (bad).
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Jan 27, 2010
I've created a templated user control by following the example on the microsoft support pages. I won't post it all but the important part of the CS file looks as follows:
[Code]....
I'm not sure if the whole _CurrentDataItem business is required, I don't think so.The problem I've got, is that I've tried nesting it inside a FormView control so I can use it to display a record from a database. My ASPX looks like this:
[Code]....
Now, the bound properties (TitleText and TitleSubText) bind correctly, but the nested / template content is blank when the page loads. I'm not sure if this is something to do with the order in which everything is loaded or because I'm missing some code in the SimpleTemplate to get it to bind (etc.).
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Jan 5, 2011
Is there some way to intercept the HTML output stream in asp.net and make modifications? Eg using httpmodules or something? I know this is possible using java servlets and assume there must be an elegant way to do this with asp.net.
My purpose is to combine the many javascript files into one composite script which has been minified/packed, to make the page load faster.Eg, if my page normally outputs the following in the page head:
<script type="text/javascript" src="/scripts/blah.js"></script>
<script type="text/javascript" src="/scripts/yada.js"></script>
I want to replace that with the following:
<script type="text/javascript" src="/scripts/all.js"></script>
(also i realise i'll have to create all.js somehow).
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Dec 7, 2010
I want to render something like this (with ASP.Net Controls in the codebehind):
<ul>
<li class="first"><h1>This is a caption</h1></li>
<li><a href="#" title="" target="_self">Foo</a></li>
<li><a href="#" title="" target="_self">Foo1</a></li>
<li><a href="#" title="" target="_self">Foo2</a></li>
<li><a href="#" title="" target="_self">Foo3</a></li>
<li><a href="#" title="" target="_self">Foo4</a></li>
</ul>
<ul>
<li class="first"><h1>This is a another caption</h1></li>
<li><a href="#" title="" target="_self">Foo5</a></li>
<li><a href="#" title="" target="_self">Foo6</a></li>
<li><a href="#" title="" target="_self">Foo7</a></li>
<li><a href="#" title="" target="_self">Foo8</a></li>
<li><a href="#" title="" target="_self">Foo9</a></li>
<li><a href="#" title="" target="_self">Foo10</a></li>
<li><a href="#" title="" target="_self">Foo11</a></li>
</ul>
The amount of li elements that will be rendered into each ul is determined at runtime. Each link in a li belongs to into a specific ul (the one containing a specific caption. Imagine this as a kind of a treeview with nodes and subnodes) During the bind Event I need access to an ASP:HyperLink that will be rendered into the a-element. Which databound ASP.Net control should I pick for this? Looks like a repeater in a repeater, which should make the databinding process ugly. I'm thinking about creating this HTML-Output with StringWriters myself.
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Apr 15, 2010
I want to access a label in templated user control.
I find this code in internet, but it doesn't work.
Error:Object reference not set to an instance of an object.
public static Control FindControl(Control parent, string id)
{
Control recurse;
if (parent.ID == id)
[Code]....
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Apr 20, 2010
How to change the values in gridview on text change of templated control without databind again?the value of templated text boxes should change If i change the value of one of the templated textbox then accordingly(By mathematical calculations) the vlaues of all tempated textboxes should also change.
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Nov 10, 2010
I have a ObjectDataSource and a ListView referencing it.
I have created a Templated User Control (see:
http://msdn.microsoft.com/en-us/library/36574bf6.aspx) and placed it in the ListView's InsertItemTemplate
It has one template <ContentTemplate>. Inside that template, I've defined a couple of server controls with their properties = '<%# Bind("colName") #>'.
See below:
[Code]......
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May 25, 2010
I want to be able to do something like this
<test:TabControl id="" runat="server"....>
<ItemTemplate>
<tabItem label="tab1" />
<tabItem label="tab2" />
</ItemTemplate>
</test>
The idea being here is that the only acceptable items in "ItemTemplates" are the tabitem types. There are many asp.net controls that use this, for example the ScriptManager class only allows you to specify certain types of objects under its various collections. Maybe thats the key to this.. I want to add a collection as opposed to a template. The idea is that in code I will then iterate over each "tabItem" and create the tab as I want it to look (probably rendering div's etc). Ive had a look at most of MSDN link on how to create templated controls but it doesnt seem to do exactly what I want it to. Would be grateful for some assistance.
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Jan 5, 2011
I would like to find a way to read a txt file (in my case delimited by €). I need to change the order of the columns and also add and remove some columns. My output file should be a txt file delmited by ;.
I tried Jet.OLEDB to read the file and put it into a datatable and then used a stringBuilder and streamwriter to get an output file in .txt format. However. This does not me since IŽ, reading the txt file from start to end and my output will be the same. It does not seem like I can have a custom sql statement when reading the file. The only query that works is
Dim da As New System.Data.OleDb.OleDbDataAdapter("Select * from 1.txt", TextConn)
How can I possible modify a txt file?
This is my code for now:
[Code]....
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May 28, 2010
I'm creating a custom templated composite control. If there is no 'ItemTemplate' specified in the mark-up, how do I create a default template programmatically?
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Dec 20, 2010
I am trying to access a control from the code behind in a tmeplated user control and and keep getting an object reference exception.
Is it possible to access these controls. I have tried the find control and just referencing the object i.e. this.someID, non of which worked.
Here is my templated control:
[Code]....
Here is the template ascx code:
[Code]....
Here is the test user control that is using the template:
[Code]....
Here is the codebehind for the test user control:
[Code]....
I have also tried this which throws the same error:
Label label = (Label)this.Page.FindControl( "DateTimeLabel2" );
label.Text = DateTime.Today.ToString();
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Sep 9, 2010
I'm trying to run the templated user control example provided by MSDN. Code is as follows:
So according to MSDN this should implement as follows:
[code]...
Designer complains that content is not allowed between the opening and closing tags of TemplatedFirstControl and that FirstTemplate is not supported. So what's missing? I duplicated MSDN's code verbatim
MSDN Article: [URL]
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Feb 8, 2011
I'm working on a user control that renders couple nested divs (a rounded corner box to be frank). This is a templated user control, which means that user can put any control he wants into the header, body or footer of this box. Everything is working fine, except the fact that server-side controls can't be retrived from my box. Take a look at this code:
[Code]....
Now codebehind of that control:
[Code]....
I have cut out all the unimportant stuff.Now when I use this control:
[Code]....
I want to access controls in page codebehind file (on Page Load): LiteralNewses.Text="";
but compiler returns an error that LiteralNewses doesn't exist. Also FindControl method can't find this literal.Any tips on what's wrong with this code? According to MSDN, setting TemplateInstance to Single ensures that controls from template will be accessible but not in my case...
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May 21, 2010
i am developing a tree view component which should be data driven and amendable instead default layout provided by .net can we change that proper hierarchial structure like organization chart is there any chance to provide with an hyperlink to redirect other page or content view control below to display the content related to it.
i am trying to use silverlight with c#.
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Mar 30, 2010
In my asp.net web page i have a dropdown box. Say like i have to bind EmployeeName to this dropdown box to show up as items.
I am using a dataTable to bind to this grid by having two columns in DataTable (EmployeeId and EmployeeName). But i am only binding the EmployeeName to the dropdown list box.
In the UI, after the user selects an Employee, I need to pass that employee's id to a function. Is there any way, i can directly pass the underlying data (EmployeeID in the DataTable attached to this dropdown), when the user selects the EmployeeName from the dropdown. Or i will have to make a roundtrip to the database and get the selected Employee's Id and then pass it to the function.
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Jan 6, 2010
I have an AJAX tab container with 2 panels within aspx page. Each panel hosts an ascx control. Each control contains GridView and FormView that are databound - 1st control to the parent table and 2nd - to the child. The 2nd control/tab contains standard DropDownList that is bound to the parent values so the user can select a parent to create "child" for. everything works fine except when the parent (on the 1st tab control) is created/updates the ObjectDataSource on the 2nd tab does not getting refreshed. Only after refreshing the hole page I can see the new "parent" value in the ddl on "child" page. I use strongly typed dataset. How I can programmatically refresh the DataSource? Simple rebinding didn't make a dent. Do I need to refresh page, the tab container, tab panel?
<asp:Content
ID="Content1"
ContentPlaceHolderID="ContentPlaceHolder1"
Runat="Server">
[Code]....
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