I have a UserControl that I need to add dynamically. I tried to follow this MSDN article, but I'm not having any success....
http://msdn.microsoft.com/en-us/library/c0az2h86.aspx
The UserControl is basically an image gallery, and it loads some pictures based on an ID. My idea was to make this ID available as a property. Then when I create an instance of the control, I could set this ID and add it to the form.
I added a reference to the control in the .aspx page that will use it, like this:
<%# Reference Control="~/PictureGallery.ascx" %>
And in the UserControl I added a ClassName like this:
<%# Control Language="C#" AutoEventWireup="true" CodeFile="PictureGallery.ascx.cs"
Inherits="PictureGallery" ClassName="PictureGallery" %>
When I try to create an instance in the .aspx.cs like the article suggests, Dim gallery As ASP.PictureGallery, I get an "Type ASP.PictureGallery is not defined".
The article mentions a namespace, ASP, and I tried importing it to the .aspx.cs with no luck.
So, I'm not able to get a reference to the UserControl.
How can it be fixed?
It sounds like you are confusing two separate ways of working with a UserControl.
One way is to register the control on your page so that you can put it into the page at Design Time e.g.
<div>
<asp:PictureGallery id="myGallery" runat="server" MyProperty="SomeValue">
</asp:PictureGallery>
</div>
The second is programmatically (or dynamically) adding it into the page at runtime in your code behind. If so, then you need to use the LoadControl function which is mentioned in the sample. You do not need to register the control in the aspx file if you do this.
e.g.
Dim gallery as PictureGallery = LoadControl("~/PathToControl/gallery.ascx")
gallery.MyProperty = "SomeValue"
placeHolder.controls.add(gallery)
edit
What is the class name of the control in the code behind...something like this:
Partial Public Class MyControlsClassName
Inherits System.Web.UI.UserControl
That is the type you need to use when you declare it. Is it within a namespace perhaps?
I don't think you've placed the control in your code behind. You may well have created the reference, but do you have a tag such as <asp:PictureGalary id="gallary"></asp:PictureGalary> anywhere in your aspx?
The ASP namespace is generated at run time- user controls get "compiled" as they are used by .aspx pages so this is why you get the error message "Type ASP.PictureGallery is not defined".
When adding user controls dynamically you should use the Page.LoadControl method:
Page.LoadControl("~/PictureGallery.ascx")
Related
While trying to insert controls in my page with the following block of code, i got this exception
The Controls collection cannot be modified because the control
contains code blocks
Literal lite=new Literal();
lite.Text = #"<div class='cookieLaw_slidesharey'><a id='cookieLaw_slideshare' href='#'><img src='/img/content/cookielaw_slideshare.jpg'/></a></div>";
Control control = this.FindControl("PlaceHolder");
control.Controls.AddAt(0,lite);
I tried to follow the advices written in this thread:
"The Controls collection cannot be modified because the control contains code blocks"
Which are basically:
replacing <%= %> with <%# %>
And adding
Page.Header.Databind() in the page load
But i get the following exception:
Object reference not set to an instance of an object.
Thank you for your help.
PS: i'm using .NET 3.5
Check if your "PlaceHolder" has a runat=server attribute. That should already help. You can address that control by it's id then instead of using FindControl.
The reason why your Page.Header.Databind() is not working is probably because you don't have a head section with the runat=server like in the example you copied from. They were adding controls in the header there which can be slightly different.
I'm working with referencing user controls on my ASPX page and I'm wondering what the difference is between these two page directives.
#Reference
#Register
#Register is primarily used for registering tag prefixes to declaratively use controls within a page.
<%# Register tagprefix="my" namespace="MyNamespace" %>
<my:CustomControl runat=server />
#Reference is primarily used to refer to a page or user control (by file name or virtual path) to programatically refer to members of the page or control.
<%# Reference Control="MyControl.ascx" %>
<% MyControl ctrl = (MyControl) Page.LoadControl("MyControl.ascx");
ctrl.CustomProperty = "..."; //REFERENCE directive is needed to access property
%>
#Register is the more commonly used directive. You use this when you want to use a user control in your aspx or ascx page declaratively. #Register associates the control with a specific prefix and you can then use it in your markup.
#Reference only tells ASP.NET to compile the other control when your aspx or ascx page is compiled. That makes sure it is available at run-time and can be added to your control hierarchy programmatically. This is less common since dynamically changing user controls at runtime is not comon.
Here's a good blog post about it.
http://weblogs.asp.net/johnkatsiotis/archive/2008/08/13/the-reference-directive.aspx
I'm trying to load User Control from another project, And I like to do it with it's name space:
<%# Register TagPrefix="IPGostar" Namespace="IPGostarPorject" Assembly="IPGostarPorject" %>
but this way when I use this server tag:
<IPGostar:DataGrid runat="server" ID="DataGrid1"></IPGostar:DataGrid>
the Page_Load of the DataGrid.ascx.cs will load but the content of ascx file won't load.
It's like this tag only calls the cs file and not the ascx file at the first place..
In this case, is it okay to load a .ascx user control file inside a cs file? (for example on Page_Load function we render the ascx file) and if it is okay how can I do that?
Second am I on the wrong path here?
Modfiy register tag to something like
<%# Register TagPrefix="IPGostar" TagName="IPGostar" Src="DataGrid.ascx" %>
If you are using a user control you have to specfiy the Source file. Your syntax holds good for custom controls.
You need to look into loading the control using Page.LoadControl().
At runtime, the ascx inherits from the class defined in the ascx.cs. They are not the same thing. The control defined in the ascx is a subclass of that in the ascx.cs.
If you want to distribute a control entirely as a binary, you will need to rewrite it as a ServerControl rather than a UserControl with an ascx.
You can't render the ASCX from the Page_Load of the class in the code behind. That won't work how you are thinking it might.
I have a web application that has a page that loads the content from the database. I want to be able to put a form in the dynamic content, but .net doesn't let the inside form perform it's action. Is there a way to allow this or some other way I can get a form on a dynamic content page?
--EDIT--
I think I need to clarify something. This is an aspx page that loads content from the database. As far as I know, the text I pull from the db and stick in the Label is never compiled or processed by the .net wp, thus I can't use the code behind to fix this issue.
This is a common problem, when you want to have a non-postback form to a 3rd party site (like a PayPal button, for example).
The problem occurs because HTML doesn't let you have form within a form, and most ASP.NET pages have a <form runat="server" /> "high up" in the HTML (or in the Master page).
My favorite solution is to hide the "high up" form tag, while still showing all of the content. Then you can feel free to dump any tags you want in the body. If you do this dynamically you can choose on a page-by-page basis which pages have custom forms.
I created a class called GhostForm.cs to handle this. You can read all about it here:
http://jerschneid.blogspot.com/2007/03/hide-form-tag-but-leave-content.html
There can only be one form on the page (the asp form); you have to use that form somehow.
To clarify, there can only be one form processed.
Not with webforms, no. You have to work within the one, full page form by using an event handler connected to a Button to LinkButton. Fortunately, it's pretty easy to do:
foo.aspx:
...
<asp:TextBox id="txtFoo" runat="server" />
<asp:Button id="btnFoo" runat="server" onclick="btnFoo_Click />
...
foo.aspx.cs:
...
protected void btnFoo_Click(object sender, EventArgs e)
{
string s = txtFoo.Text;
// do something with s
}
...
Dino Esposito has an article from MSDN magazine that covers handling multiple forms or "simulating" sub forms in ASP.Net that might just answer all your questions.
http://msdn.microsoft.com/en-us/magazine/cc164151.aspx
Any work around would be hacky and very ugly. By design asp.net uses a form tag to post and get data. This is why they call it a Web Forms Application. Html does not allow nested forms. What you want to do is use a WebRequest in your code behind.
If you are trying something like a paypal button you could simply use something like this.
Markup:
<div id="PayPalButtonContainer" runat="server"></div>
Code Behind:
public static string GetPayPalButtonMarkup()
{
const string markup = #"https://www.paypal.com/cgi-bin/webscr
?cmd=_xclick&business={0}
&item_name=Widget
&amount={1}
¤cy_code=USD";
return markup;
}
PayPalButtonContainer.InnerHtml = string.format(GetPayPalButtonMarkup,"YOUR PAYPAL USER NAME", "YOUR PRICE VALUE");
you either have to deal with the postback by adding a server side click event handler to what you want to be the "sub forms" submit button (this is how web formas deals with multiple submit type buutons on the same page) or do soemthing clever with AJAX if you dont want a full post back
I've run across this issue before. One workaround that I have done is to place my code that I want my action to be done upon inside of an asp:Panel. With the panel you can set the attribute of "DefaultButton" to a button inside of the panel, and clicking the button (or pressing "enter") will fire that button's click event. I've found this quite handy when wanting to submit a "form" by pressing enter when I have a master page that contains the only allowable asp:Form.
Hope this helps.
When I first came across this problem, I found the simplest solution for me was to simple COPY and PASTE the Master page and give it a slightly different name, something like:
SiteNameMasterPage 'Default page with FORM tag
SiteNameMasterPageNF 'No Form tag
And then depending on wether I wanted a FORM tag or or not, simply change the masterpage link at the top of my CONTENT-PAGES, like this
<%# Page Title="" Language="VB" MasterPageFile="~/SiteName.master" %>
<%# MasterType VirtualPath="~/SiteName.master" %>
<!-- This masterpage has the default FORM tag -->
or
<%# Page Title="" Language="VB" MasterPageFile="~/SiteNameNF.master" %>
<%# MasterType VirtualPath="~/SiteNameNF.master" %>
<!-- This masterpage does NOT have the default FORM tag -->
and then in the content page, wherever I want to place my form I can include the <form> tag
I have a number of similarly structured FormViews. In an effort to avoid duplicate markup, I've created a master page that contains the FormView, and placed a ContentPlaceHolder inside the FormView. The specific databound controls - which are the only thing that change from page to page - are then on the page that uses that master page.
So I have a master page that looks something like this:
<%# master ... %>
...
<form runat=server>
...
<asp:formview runat="server" ... >
<edititemtemplate>
... Lots of common markup ...
<asp:contentplaceholder id='FormRows' runat='server' />
... Lots more common markup ...
</edititemtemplate>
</asp:formview>
...
</form>
and a page using that master page that looks something like this:
<%# page masterpagefile="Form.Master" ... %>
<asp:content contentplaceholderid="FormRows" runat="server" >
...
<p>
Field One:
<asp:textbox runat=server text='<%#Bind("Field1")%>' id='Field1' />
</p>
<p>
Field Two:
<asp:textbox runat=server text='<%#Bind("Field2")%>' id='Field2' />
</p>
...
</asp:content>
With an existing record, the FormView sees through to the databound controls (Field1, etc) and populates them with the correct data. But when inserting or updating, it doesn't see them, and they're not included in the insert or update. In the FormView_ItemInserting event, e.Values is empty; likewise in the FormView_ItemUpdating event, e.NewValues is empty.
So:
Is there a way to provoke the FormView on the master page to see through to the databound controls inside the ContentPlaceholder?
Failing that, is there a straightforward way of identifying controls that are databound with <%#Bind(...)%> so that I can add them manually to the values bag?
There are a couple of things that come to mind why this setup will not work and may lead to more code than markup.
If you have a datasource defined in the master page it will not handle the different data bound controls from each page without adding more logic to the master page to change the query etc.
All form views will be coupled together increasing the complexity of changes down the road
I would go with separate pages for each FormView reducing the complexity of code, debugging and the ability to change
Just my two cents
I think this will prove difficult, if not possible; in fact I'm surprised that the databinding works at all!
You may want to try a different method of encapsulating your FormView control.
You could try placing the FormView control in an .ascx control with a PlaceHolder where you now have the ContentPlaceHolder.
Then on each ASPX page, you could have a mirror ASCX page that contains the filler for the placeholder. You could give them the same names (Page1.aspx uses Page1.ascx) or set up a naming convention like Page1-Content.ascx, so that your FormView ascx would figure out what it's filler control is named, use Page.LoadControl() to load the control by path, and plug that content in during the Init phase.
Now, your content controls have the advantage of being able to have public properties, so you could bind to those public properties, and have the properties shuttle the data to and from the appropriate server controls in the filler .ascx file.
Unfortunately it's double the files (because of the ASPX and ASCX required for each page) but fairly work-unintensive compared to the alternative (duplicating all that code)
Of course, you haven't told us what all your common markup is, but your common markup could go into a CommonMarkupHeader.ascx and CommonMarkupFooter.ascx as well and included on each page's unique FormView.
Where do you have server form tag? May be in content place holder insted of master page, so your values not send to server page after submit
You might be able to do something like this...
Define an interface for your "data pages" that has a method signature that returns a bindable data source..
public interface IFormViewChild {
IEnumerable GetFormData();
}
Then you can have your "data pages" implement that interface...
public class ChildDataPage : Page, IDataPage {
public IEnumerable GetFormData() {
// code to return stuff here
}
}
Finally, in your masterpage's Load() event...
if (Page is IFormViewChild) {
myFormViewControl.DataSource = ((IFormViewChild)Page).GetFormData();
myFormViewControl.DataBind();
}
Please keep in mind that this is all psudo code typed directly into this web form editor.. so it's probably wrong. But it might not be :)
Here's a provisional solution - not elegant, but it works. In the code-behind for Form.Master I have something along these lines:
Private Sub FormView1_ItemInserting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.FormViewInsertEventArgs) Handles FormView1.ItemInserting
ManuallyAddValues(e.Values)
End Sub
Private Sub FormView1_ItemUpdating(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.FormViewUpdateEventArgs) Handles FormView1.ItemUpdating
ManuallyAddValues(e.NewValues)
End Sub
Private Sub ManuallyAddValues(ByRef Values As IOrderedDictionary)
For Each Field As Core.Field In FormView1.DataSourceControl.IncludedFields
If Values(Field.Name) Is Nothing Then
Dim DataboundControl As Control = FormView1.FindControl("FormRows").FindControl(Field.Name)
Values.Add(Field.Name, GetValue(DataboundControl))
End If
Next
End Sub
This isn't so elegant because
I have to know the names of all databound controls
This relies on the assumption that the ID of each control matches the fieldname
The 'GetValue' function (not included here) is a clumsy solution: it checks for various types (textbox, dropdownlist, checkbox, etc.) and gets the string value from the appropriate property (textbox.text, dropdownlist.selectedvalue, checkbox.checked, etc.).
I'd still love to at least have a way of knowing what's bound with the '<%#Bind("Foo")%>' syntax and getting that information directly.