Is it possible to add an event to a control which is inside another control, like say a PlaceHolder control using the designer?
When the control is alone on the form this works perfectly... you simply add it from the properties window by clicking the thunder icon and clicking on the event needed.
I know I can do by adding it manually but it would just be faster if it were generated for me.
To test this, add the following to a form and try adding the OnClick event of the btnTest through the designer or properties window:
<asp:PlaceHolder ID="phTest" runat="server">
<asp:Button runat="server" Text="Button" ID="btnTest" />
</asp:PlaceHolder>
Any help is appreciated
Regards
<asp:PlaceHolder ID="phTest" runat="server">
<asp:Button runat="server" Text="Button" ID="btnTest" OnClick="bUpdate_Click" />
</asp:PlaceHolder>
I have had to do it manually in my project and as long as you match up the eventargs it was straight forward
I don't think PlaceHolder control is using for this purpose. From MSDN
The PlaceHolder Web server control
enables you to place an empty
container control within the page and
then dynamically add, remove, or loop
through child elements at run time.
The control only renders its child
elements; it has no HTML-based output
of its own.
Well I guess there is NO way it can be done through the designer, except by adding the eventhandler to the button before you put it into the Placeholder.
Thanks for the help guys...
Related
I'm currently trying to create a web based wizard tool. I have a Wizard page that contains navigation buttons and an asp panel that will contain the individual wizard panels.
<asp:Panel ID="wizardControlPanel" runat="server">
<!-- Wizard panel goes here -->
</asp:Panel>
<asp:Button ID="backButton" runat="server" Text="< Back" OnClick="BackButton_Click" />
<asp:Button ID="nextButton" runat="server" Text="Next >" OnClick="NextButton_Click" />
<asp:Button ID="cancelButton" runat="server" Text="Cancel" PostBackUrl="~/"/>
One control dynamically fills a checkboxlist
<asp:Label ID="Title" runat="server" Text=""></asp:Label>
<asp:Label ID="DescriptionLabel" runat="server" Text ="Description for the wizard"></asp:Label>
<asp:CheckBoxList ID="ProjectSelector" runat="server" DataTextField="ProjectName" DataValueField="Id" ></asp:CheckBoxList>
I dynamically load this control into my wizardControlPanel once the checkbox is populated.
WizardControl = (BaseWizardControl)LoadControl(("~/Views/" + e.ControlType.Name + ".ascx"));
wizardControlPanel.Controls.Add(WizardControl);
The problem is; on postback I then need to be able to find out which checkboxes were checked server side, but the control no longer exists.
I can't find it on the _page variable. Running in to problems (I think) because I am adding the control to a content holder. How can I get this control back?
It is there, you just won't be able to access it using an ID. You'll need to find it by looking through the wizardControlPanel.Controls collection. I think there is a property that represents the filename you used. But it would be best to use the debugger to track down either where it is in the collection or an identifier you can use to find it.
Having done this once or twice, I think I also remember that you'll need to recreate the control prior to the OnLoad event of the life cycle so that the postback will be able to populate it.
As Markus says, there is probably a better way to do what you are trying to do. But if you MUST load this dynamically, this is how you should go about locating it.
If you add controls dynamically in ASP.NET WebForms, you need to re-add them manually very early in the page lifecycle of the PostBack (e.g. by overriding OnInit and creating the control with the same id in this code) in order to be able to retrieve the values. See this link for a How-To.
The following sample shows the basic steps. It consists of an ASPX-page that contains a Panel as a placeholder:
<asp:Panel ID="wizardPanel" runat="server">
</asp:Panel>
<asp:Button ID="btn" runat="server" Text="Do a postback" />
<br />
<asp:Label ID="lbl" runat="server" />
This is the codebehind-file:
public partial class DynamicUserControls : System.Web.UI.Page
{
protected UserControl userCtrl;
protected override void OnInit(EventArgs e)
{
base.OnInit(e);
if (Page.IsPostBack)
CreateUserControl();
}
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
CreateUserControl();
else
{
lbl.Text = "The following values were selected: " + string.Join(", ", ((IGetSelectedValues)userCtrl).SelectedValues);
}
}
private void CreateUserControl()
{
if (Request["UserCtrl"] == "A")
{
userCtrl = (UserControl) LoadControl("~/MyUserControlA.ascx");
userCtrl.ID = "myUserCtrl";
wizardPanel.Controls.Add(userCtrl);
}
else if (Request["UserCtrl"] == "B")
{
userCtrl = (UserControl)LoadControl("~/MyUserControlB.ascx");
userCtrl.ID = "myUserCtrl";
wizardPanel.Controls.Add(userCtrl);
}
}
}
The basic steps are the following:
The page determines the user control type to be created upon a Request parameter during Page_Load (or later if necessary). It assigns the ID myUserCtrl to the UserControl.
Upon a PostBack, the page inspects the Request parameters again and re-creates the UserControl with the same ID myUserCtrl. This is important so that ASP.NET can retrieve the new values of the control from the postback data after the page initialization phase. The hardest part is usually to decide which user controls to create, because the data that are available in OnInit is usually not too many.
In Page_Load, the user control can be accessed and the values that were posted back are available. The UserControls in the sample contain a CheckBoxList and implement an interface that allows to retrieve the values that were selected by the user.
In most cases it is easier to find a different approach. Maybe you can use a MultiView control for your wizard that contains the UserControls for the wizard pages as static content. See this link for a description of how to use the MultiView control. If there are not too many (read unlimited) different UserControls to use, this approach is much more stable.
I was looking in the wrong place. Page.Form as opposed to Page.Request.Form. Due to the fact the checkboxlist is already defined in the user control, it's name is traceable in this variable. This way I can keep the current wizard structure.
<ContentTemplate>
<div class="detail_purchase_button">
<a class="commandbutton" href='/Courses?RestoreFilters=1'>Return to Catalog</a>
<%# linkAddToCart %>
</div>
</ContentTemplate>
string url = "/Cart?AddItem={0}", DataItemID;
linkAddToCart = new HyperLink();
linkAddToCart.CssClass = "commandbutton";
linkAddToCart.NavigateUrl = url;
linkAddToCart.Text = "Add To Cart";
The button within the anchor tag shows up on the page. However, the Hyperlink button does not appear at all.
The second block of code is running in the Page_Load event (I will put it in a method after I get it to work) and is referencing a public Hyperlink field.
Thanks for any help.
Define the hyperlink control via markup in the presentation file.
<asp:HyperLink id="lnkAddToCart" runat="server" />
Place it where you need it to be. You can still reference its properties in your codebehind.
lnkAddToCart.CssClass = "commandbutton";
lnkAddToCart.NavigateUrl = url;
// etc.
If you were to define the control dynamically instead, you would need to add it to the appropriate container, such as a panel or placeholder
<asp:Panel id="theContainer" runat="server" /> or
<asp:PlaceHolder id="theContainer" runat="server" />
...
// define the HyperLink as in your original code snippet
theContainer.Controls.Add(lnkAddToCart);
However, unless you absolutely need to dynamically create the control, adding it to the the ASPX at design time is best. You can always set Visible="false" (to the markup, .Visible = false; in code) if it does not need to be displayed all the time.
Your question seems a bit vague but I am trying to answer based on what I understand out of it. Please ignore if I misunderstood your question.
It is not possible to add an hyperlink like this. First put a placeholder(i.e. panel) within the contenttemplate and then add the hyperlink into the placeholder from code behind.
<a class="commandbutton" href='/Courses?RestoreFilters=1'>Return to Catalog</a>
<asp:Panel id="pnlLink" runat="server"></asp:Panel>
</div>
</ContentTemplate>
And then in the code behind
string url = "/Cart?AddItem={0}", DataItemID;
linkAddToCart = new HyperLink();
linkAddToCart.CssClass = "commandbutton";
linkAddToCart.NavigateUrl = url;
linkAddToCart.Text = "Add To Cart";
pnlLink.Controls.Add(linkAddToCart);
Try setting an ID to the linkAddToCart control that you create dynamically. Your code does not define an ID for it. With that being said, I would recommend doing this the way Anthony suggested. I don't see the need to do this kind of thing. If you want to have some logic for making appear in certain cases, just define it in your markup with Visible="false" and make it visible when you need to.
Is it possible to use an UpdatePanel that has like a few text boxes, and a search button, and then perhaps another UpdatePanel that has a gridview in it to return the results of what was searched. When the user clicks search it hides the boxes, and displays the gridview. Can I do this with UpdatePanels? I am using c# for my coding. Or should I be doing this another way?
You only need one UpdatePanel in that case and setup a Trigger to your search Button.
Put only the controls that will be refreshed in your UpdatePanel.
Example:
<asp:TextBox ID="txtSearchCriteria" runat="server" />
<asp:Button ID="btnSearch" runat="server" OnClick="btnSearch_Click" />
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btnSearch" EventName="Click" />
</Triggers>
<ContentTemplate>
<asp:GridView ID="grdSearchResults" runat="server">
</asp:GridView>
</ContentTemplate>
</asp:UpdatePanel>
Implement the btnSearch_Click function to execute your search and bind the results to the GridView. The UpdatePanel will handle the ajax call and replacing of the HTML that the GridView will produce.
You want to keep as much out of the UpdatePanel as possible and only include what will actually change because it is transmitting that HTML with each update so it's a waste of resources if you are not actually doing anything to those controls with each action. That is why a trigger is best to be used in this case which will hook the UpdatePanel to the Click event outside of the UpdatePanel scope.
Read up more on UpdatePanel and how triggers work on MSDN.
If I understand the question correctly, you can do that with two <asp:Panel> controls inside the <UpdatePanel>. One panel for the textboxes, and the other for the gridview. You set which panel to show in the codebehind, depending on whether you're expecting your user to enter search criteria, or review the search results.
Yes you can.
You also could use just one update panel. Since you the Search Form (could be in a Panel) and the GridView inside the UpdatePanel.
I have two asp.net buttons inside a template (Expand and Collapse)
I want to implement a simple client side javascript function to hide the expand button after press it and show the collapse button and vice versa.
<asp:Button ID="btnExpand" runat="server" CommandName="Expand"
CommandArgument='<%# Container.DataElement("Id")%>' Text="+" />
<asp:Button ID="btnCollapse" runat="server" CommandName="Collapse"
CommandArgument='<%# Container.DataElement("Id")%>' Text="-" />
I tried OnClientClick event but I didn't know how to get the sender button and the second button from javascipt because they're in a template and their IDs will be generated.
I tried also to change their visibility from the code behind in the server (by Visible property) but the problems is the event handler will be fired after the postback and the changes will not be applied in the client.
Any help !!
sorry if the question is silly, I'm new in the web development.
Thanks in advance.
Use ClientID like:
<!-- Supposing you have the following button control -->
<asp:button id="myButton" runat="server" />
<script type="text/javascript">
var theID = '<%= myButton.ClientID %>';
// Now do whatever you like with it.
</script>
Be careful where you place that code. You need to make sure that the html client renderer has finished creating that item.
In the function where you are implementing the hide and show template, put $("#buttonID").hide();.
I am working on an asp.net web application where I have predefined panel in my project with
CSS. Now i want to create another panel with same design and CSS at run time at multiple times. I have a button control when i will click that button it will add another panel.
Please help me to add another panel with same criteria.
If it is something that you plan on reusing, I'd suggest you utilize a user control for this. You can them simply add a new instance of the control on your page.
A few things worth looking into:
https://web.archive.org/web/20210707024005/http://aspnet.4guysfromrolla.com/articles/081402-1.aspx
http://aspalliance.com/565
http://msdn.microsoft.com/en-us/library/c0az2h86.aspx
If you wanted to accomplish this with a postback to the page, add this to your event...
//MyControl = Custom User Control
var myControl = (MyControl) Page.LoadControl("MyControl.ascx");
this.ControlContainer.Controls.Add(myControl);
Like RSolberg said, you could write a User Control and add it multiple times:
<my:UserControl id="MyControl1" runat="server" />
<my:UserControl id="MyControl2" runat="server" />
<my:UserControl id="MyControl3" runat="server" />
Of course, your User Control can be as simple or as complex as you like, thus having repeated functionality on your page.
However, depending on your exact needs you might want to consider something like an ASP.NET Repeater, or ListView, or DataGrid control. With something like a Repeater, you can bind data to it, and have that data be displayed in a list/grid, that has a common look and feel. You can give your Repeater a HTML/CSS template for the header, items, and footer sections too to make it look consistent and professional.
<asp:Repeater id="MyRepeater" runat="server">
<HeaderTemplate>
<h1>Products</h1>
</HeaderTemplate>
<ItemTemplate>
<p>
Product name: <%# Eval("ProductName") %>
</p>
</ItemTemplate>
</asp:Repeater>
and in your code just do this:
MyRepeater.DataSource = products;
MyRepeater.DataBind();
There are many ways of doing what you're asking in ASP.NET - be a bit more specific and we'll be able to give you more specifc help.
Couldn't you just create a new panel in the code behind on the button's "On_Click" event? That would be my suggestion. You may need to have a placeholder to add the panel into something so it appears on the page.