I have a class method which calls FindControl and creates a generic control reference as follows:
Control oControl = oCriteriaTable.FindControl(sControlName);
The generic oControl variable may end up containing a reference to a normal form control (e.g. Textbox, DropDownList) or it may end up with a reference to a UserContol (e.g. csiDateRange)
For Textbox or DropDownList Controls I can access the generic control's properties by casting as follows:
However..... This code is contained in a regular class file not an ASP page. The (ASP.csiDateRange) cast fails to compile because the ASP namespace is unknown. How do I reference that namespace (and that of my UserControl) in my class?
I have the follow using directives for the class:
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;
using System.Collections;
The UserControl Control Directive is as follows:
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="csiDateRange.ascx.cs" Inherits="UserControls_csiDateRange" Classname="csiDateRange"%>
Please note again that the (ASP.csiDateRange) works perfectly in an ASP page, Just not in a regular class definition.
your user control would need to have a base class, specified on same place where this class so that it could reference the user control with the base type. See Rick Strahl's excellent post about the subject:
http://west-wind.com/weblog/posts/3016.aspx
I really apprecaite your reply as almost none of my posts here are ever responded to. Unfortunately, I don't understand your suggestion. My user control does have a base class: System.Web.UI.UserControl. The article you referred to is a good one but I don't understand
how it answers this issue. As a metter of fact the author states:
"For normal application usage this is not a big issue as in most applications developers will drop controls onto a Page visually. However, for dynamically loaded user
controls things are going to be tricky – I don’t see how you can truly dynamically load a user control any more assuming you can’t add the <@ Register > directive to the page explictly. Maybe there’s some way to do the equivalent of <@ Register > in code?
If there is, I couldn’t find it…"
The problem he states is nearly identical to my issue in that this is a class, not a page, so there is no where to add a <@ Register> or <@ Reference > directive so that
I can access the properties of the UserControl. Could you provide a short example of the approach you are suggesting?
Meanwhile I have come to a less than ideal workaround using reflection. Below is an example for others who may be wrestling with this issue:
...
...
using System.Reflection;
...
static public class MyTestClass {
// This WON'T work because namespace ASP is unknown in a regular class
/*
static public String GetAPropertyValueViaReflection() {
Control oControl = oSomeContainer.FindControl("myKnownUserControl");
sControlValue = ((ASP.myKnownUserControl)oControl).SomeKNownProperty;
return sControlValue;
}
*/
// This DOES work until I can figure out how to get a true reference to "myKnownUserControl"
static public String GetAPropertyValueViaReflection() {
Control oControl = oSomeContainer.FindControl("myKnownUserControl"); PropertyInfo pi = oControl.GetType().GetProperty("SomeKNownProperty");
sControlValue = pi.GetValue(oControl, null).ToString();
return sControlValue;
}
}
Exaclty, your control has that as base class when you could basically in the code use only that type to refer to the UC. However, if you write your own class (in the same library where you try to reference it), which derives from System.Web.UI.UserControl
public class MyClass : System.Web.UI.UserControl
{
}
and specify all the members etc here (you'd also need to use CodeFileBaseClass attribute in case they are control members). Essentially mechanism Rick has described like this
This is a pretty major change in the way ASP.NET works. There’s a workaround for this, but it’s not pretty:
Create a base class for your page and make it inherit from Page
Store this Page either in APP_CODE or in a separate assembly so it’s visible to your pages
Implement your Public interface on this base Page
Then create your Page and make it inherit from this base Page
Now when you need to cast, cast to the base type
BTW: I've commented on that post about the @Register
re: Understanding Page Inheritance in ASP.NET 2.0
tammi 12, 2006 04:51Teemu Keiski
Equivalent of using @register in code is running the same through Page.ParseControl. Ugly as hell but seems to work,
Dim c As Control = Page.ParseControl("<%@Register TagPrefix=""rc"" TagName=""c"" Src=""subfolder/uc_subfolder.ascx""%><rc:c runat='server' />")
form1.Controls.Add(c)
this does not work. what if i am inside a class (say, MyClass.vb) and have a method that passes a page variable to it. I want to add a control (say, MyControl.ascx) to that page dynamically, but I can't simply go
dim ctl as MyControl = CType(page.LoadControl("MyControl.ascx"), MyControl)
MyControl isn't recognized as a type, and so far as I've seen, there's no workaround for this. Why did ASP.NET stop supporting user controls as objects? Seems stupid to me.
It did not, but provided two models for working with it. The model which doesn't recognice types without having a base class or @reference directive, a web site project, does so to avoid explicit compilation step when making changes during development. And
since there isn't that step, the type cannot be implicitly known as it's not compiled beforehand into an assembly, but you must tell what it is. Other reason is that App_Code is compiled before user controls or pages.
When using Page.LoadControl you get back a control instance but the compiler hasn't been told what MyControl type is. And it can only be told by having
<%@ Reference Control="MyControl.ascx" %>
And if you need that type in a class, you need to declare the base type in App_Code or external control project/class library.
The other model, Web Application Project also called WAP, which works similarly to the model in VS2003, has explicit compilation step, and therefore the type of the user control is known available on the entire project.
dim ctl as MyControl = CType(page.LoadControl("MyControl.ascx"), MyControl)
You can change it to:
dim ctl as Object = CType(page.LoadControl("MyControl.ascx"), Object)
This effectively abstracts the control to a level where you can make use of the fact that the Object class allows you to reference any property at design time. (ie, Late binding)
ctl.Lala will compile happily, but will fail at runtime if no "Lala" property exists. If the "Lala" property does exist at runtime, then you're in business.
I just applied this technique to an instance where I had a class in app_code that needed to reference a usercontrol on several pages.
awjenning
Member
135 Points
28 Posts
Accessing a UserContol's custom properties in a regular class (not a page class)
Oct 13, 2006 08:29 PM|LINK
Hello,
I have a class method which calls FindControl and creates a generic control reference as follows:
Control oControl = oCriteriaTable.FindControl(sControlName);
The generic oControl variable may end up containing a reference to a normal form control (e.g. Textbox, DropDownList) or it may end up with a reference to a UserContol (e.g. csiDateRange)
For Textbox or DropDownList Controls I can access the generic control's properties by casting as follows:
sControlValue = ((TextBox)oControl).Text;
sControlValue = ((DropDownList)oControl).Text;
The problem I am having is that I cannot figure out how to cast when a UserControl is in the generic so that I can get to it's custom properties.
If this code is contained in an ASP page I can cast as follows:
sControlValue = ((ASP.csiDateRange)oControl).SomeCustomProperty;
However..... This code is contained in a regular class file not an ASP page. The (ASP.csiDateRange) cast fails to compile because the ASP namespace is unknown. How do I reference that namespace (and that of my UserControl) in my class?
I have the follow using directives for the class:
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;
using System.Collections;
The UserControl Control Directive is as follows:
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="csiDateRange.ascx.cs" Inherits="UserControls_csiDateRange" Classname="csiDateRange"%>
Please note again that the (ASP.csiDateRange) works perfectly in an ASP page, Just not in a regular class definition.
Any ideas????
Thanks,
Tony
c# User Controls Class
joteke
All-Star
46224 Points
6896 Posts
ASPInsiders
MVP
Re: Accessing a UserContol's custom properties in a regular class (not a page class)
Oct 14, 2006 01:18 PM|LINK
Hi,
your user control would need to have a base class, specified on same place where this class so that it could reference the user control with the base type. See Rick Strahl's excellent post about the subject: http://west-wind.com/weblog/posts/3016.aspx
Teemu Keiski
Finland, EU
awjenning
Member
135 Points
28 Posts
Re: Accessing a UserContol's custom properties in a regular class (not a page class)
Oct 14, 2006 05:44 PM|LINK
Joteke,
I really apprecaite your reply as almost none of my posts here are ever responded to. Unfortunately, I don't understand your suggestion. My user control does have a base class: System.Web.UI.UserControl. The article you referred to is a good one but I don't understand how it answers this issue. As a metter of fact the author states:
"For normal application usage this is not a big issue as in most applications developers will drop controls onto a Page visually. However, for dynamically loaded user controls things are going to be tricky – I don’t see how you can truly dynamically load a user control any more assuming you can’t add the <@ Register > directive to the page explictly. Maybe there’s some way to do the equivalent of <@ Register > in code? If there is, I couldn’t find it…"
The problem he states is nearly identical to my issue in that this is a class, not a page, so there is no where to add a <@ Register> or <@ Reference > directive so that I can access the properties of the UserControl. Could you provide a short example of the approach you are suggesting?
Meanwhile I have come to a less than ideal workaround using reflection. Below is an example for others who may be wrestling with this issue:
...
...
using System.Reflection;
...
static public class MyTestClass {
// This WON'T work because namespace ASP is unknown in a regular class
/*
static public String GetAPropertyValueViaReflection() {
Control oControl = oSomeContainer.FindControl("myKnownUserControl");
sControlValue = ((ASP.myKnownUserControl)oControl).SomeKNownProperty;
return sControlValue;
}
*/
// This DOES work until I can figure out how to get a true reference to "myKnownUserControl"
static public String GetAPropertyValueViaReflection() {
Control oControl = oSomeContainer.FindControl("myKnownUserControl");
PropertyInfo pi = oControl.GetType().GetProperty("SomeKNownProperty");
sControlValue = pi.GetValue(oControl, null).ToString();
return sControlValue;
}
}
joteke
All-Star
46224 Points
6896 Posts
ASPInsiders
MVP
Re: Accessing a UserContol's custom properties in a regular class (not a page class)
Oct 17, 2006 09:57 AM|LINK
Exaclty, your control has that as base class when you could basically in the code use only that type to refer to the UC. However, if you write your own class (in the same library where you try to reference it), which derives from System.Web.UI.UserControl
public class MyClass : System.Web.UI.UserControl
{
}
and specify all the members etc here (you'd also need to use CodeFileBaseClass attribute in case they are control members). Essentially mechanism Rick has described like this
This is a pretty major change in the way ASP.NET works. There’s a workaround for this, but it’s not pretty:
BTW: I've commented on that post about the @Register
re: Understanding Page Inheritance in ASP.NET 2.0 tammi 12, 2006 04:51 Teemu Keiski
Equivalent of using @register in code is running the same through Page.ParseControl. Ugly as hell but seems to work,
Dim c As Control = Page.ParseControl("<%@Register TagPrefix=""rc"" TagName=""c"" Src=""subfolder/uc_subfolder.ascx""%><rc:c runat='server' />")
form1.Controls.Add(c)
Teemu Keiski
Finland, EU
jafoaz
Member
2 Points
1 Post
Re: Accessing a UserContol's custom properties in a regular class (not a page class)
Jun 13, 2007 05:17 PM|LINK
'Get the year from the page property
Dim propInfo As System.Reflection.PropertyInfo = Me.Page.GetType.GetProperty("SomePropName") Dim prop As Object = propInfo.GetValue(Me.Page, Nothing)tacoman667
Member
457 Points
106 Posts
Re: Accessing a UserContol's custom properties in a regular class (not a page class)
Jun 13, 2007 05:52 PM|LINK
Ok, this seems far too easy for how this thread is ending up. Have you tried:
myUserControl uc = this.Page.FindControl("<UserControl ID>");
If there is a proprty called MyText then you would only need to say:
uc.MyText = "My New Text!";
tacoman667
Member
457 Points
106 Posts
Re: Accessing a UserContol's custom properties in a regular class (not a page class)
Jun 13, 2007 05:53 PM|LINK
Ok, this seems far too easy for how this thread is ending up. Have you tried:
myUserControl uc = this.Page.FindControl("<UserControl ID>");
If there is a proprty called MyText then you would only need to say:
uc.MyText = "My New Text!";
edelman
Member
37 Points
22 Posts
Re: Accessing a UserContol's custom properties in a regular class (not a page class)
Jan 04, 2008 07:31 PM|LINK
this does not work. what if i am inside a class (say, MyClass.vb) and have a method that passes a page variable to it. I want to add a control (say, MyControl.ascx) to that page dynamically, but I can't simply go
dim ctl as MyControl = CType(page.LoadControl("MyControl.ascx"), MyControl)
MyControl isn't recognized as a type, and so far as I've seen, there's no workaround for this. Why did ASP.NET stop supporting user controls as objects? Seems stupid to me.
joteke
All-Star
46224 Points
6896 Posts
ASPInsiders
MVP
Re: Accessing a UserContol's custom properties in a regular class (not a page class)
Jan 06, 2008 08:11 AM|LINK
It did not, but provided two models for working with it. The model which doesn't recognice types without having a base class or @reference directive, a web site project, does so to avoid explicit compilation step when making changes during development. And since there isn't that step, the type cannot be implicitly known as it's not compiled beforehand into an assembly, but you must tell what it is. Other reason is that App_Code is compiled before user controls or pages.
When using Page.LoadControl you get back a control instance but the compiler hasn't been told what MyControl type is. And it can only be told by having
<%@ Reference Control="MyControl.ascx" %>
And if you need that type in a class, you need to declare the base type in App_Code or external control project/class library.
The other model, Web Application Project also called WAP, which works similarly to the model in VS2003, has explicit compilation step, and therefore the type of the user control is known available on the entire project.
Teemu Keiski
Finland, EU
ercarter
Member
4 Points
2 Posts
Re: Accessing a UserContol's custom properties in a regular class (not a page class)
Aug 12, 2009 08:34 PM|LINK
Using the above example:
dim ctl as MyControl = CType(page.LoadControl("MyControl.ascx"), MyControl)
You can change it to:
dim ctl as Object = CType(page.LoadControl("MyControl.ascx"), Object)
This effectively abstracts the control to a level where you can make use of the fact that the Object class allows you to reference any property at design time. (ie, Late binding)
ctl.Lala will compile happily, but will fail at runtime if no "Lala" property exists. If the "Lala" property does exist at runtime, then you're in business.
I just applied this technique to an instance where I had a class in app_code that needed to reference a usercontrol on several pages.