Loading WebUserControls `.ascx` files at runtime gives you the ability to create a dynamic page, the ability to create a page that accept plugins.

The problem is when you load WebUserControl at runtime, any postback caused by the page or the control itself will cause the control to disappear, here is a simple way explaining how to load these controls and maintaining them after postback.

First create two WebUserControls as shown below:

 

In the Save Button's code behind for both controls, write the following code:

          
            

            
          
          protected
          
          
          void
           butSave_Click(
          object
           sender, 
          EventArgs
           e)

{

   Label1.Text = TextBox1.Text;

}

        

Then create an `aspx` page with three Buttons and a Panel on the page as shown below:

 

Write the following code in page's code behind:

          
            

            
          
          protected
          
          
          void
           Page_Load(
          object
           sender, 
          EventArgs
           e)

{

             if
           (ViewState[
          "myControl"
          ]
!= 
          null
           && ((
          string
          )ViewState[
          "myControl"
          ])
!= 
          string
          .Empty)

   {

                UserControl
           uc
= LoadControl(ViewState[
          "myControl"
          ]
+ 
          ".ascx"
          ) 
          as
          
          
          UserControl
          ;

      uc.ID = ((

          string
          )ViewState[
          "myControl"
          ]);

                // Do
not clear Panel1's controls in `Page_Load` using `Panel1.Controls.Clear()`
          

                  // in some cases
the control's viewstate will be lost.

          
          
            

      Panel1.Controls.Add(uc);

            

   }

            

}

            

 

            

            
          
          protected
          
          
          void
           butLoadControl1_Click(
          object
           sender, 
          EventArgs
           e)

{

   ViewState[

          "myControl"
          ] = 
          "WebUserControl1"
          ;

             UserControl
           uc
= LoadControl(
          "WebUserControl1.ascx"
          ) 
          as
          
          
          UserControl
          ;

   uc.ID = 

          "WebUserControl1"
          ;

   Panel1.Controls.Clear();

   Panel1.Controls.Add(uc);

}

 

          protected
          
          
          void
           butLoadControl2_Click(
          object
           sender, 
          EventArgs
           e)

{

   ViewState[

          "myControl"
          ] = 
          "WebUserControl2"
          ;

             UserControl
           uc
= LoadControl(
          "WebUserControl2.ascx"
          ) 
          as
          
          
          UserControl
          ;

   uc.ID = 

          "WebUserControl2"
          ;

   Panel1.Controls.Clear();

   Panel1.Controls.Add(uc);

}

 

 

        

Run the code, and test it your self.

 

To download a sample project click the below link:

LoadDynamicWebUserControl.zip (3.23 KB)

I needed to create a CLR function to generate a report and uses ZedGraph to make a graph and save it on the disk.

I used VS 2005 to make the CLR function, but when try to add a reference to the project, all I see is few of the .Net assemblies, and there is no `Browse` button to add assemblies from the disk.

 

I did some google as usual and found this on Sql Server's Book Online:

Unsupported Libraries

Unsupported libraries can still be called from your managed stored procedures, triggers, user-defined functions, user-defined types, and user-defined aggregates. The unsupported library must first be registered in the SQL Server database, using the CREATE ASSEMBLY statement, before it can be used in your code. Any unsupported library that is registered and run on the server should be reviewed and tested for security and reliability.

And that solved the problem...

First, I'm not sure what Permission_Set ZedGrpah needs, so I'm going to mark the database as TrustWorthy so I can give the assembly an unsafe Permission_Set.

Use

Master

Go

Alter

Database Test Set TrustWorthy On

Go

Use

Test

Go

Then when I added the ZedGraph I got an error message:

Create

Assembly [ZedGraph]

From

'C:\ZedGraph\ZedGraph.dll'

With

Permission_Set = Unsafe

 

Msg 10301, Level 16, State 1, Line 1

Assembly 'ZedGraph' references assembly 'system.windows.forms, version=2.0.0.0, culture=neutral, publickeytoken=b77a5c561934e089.', which is not present in the current database. SQL Server attempted to locate and automatically load the referenced assembly from the same location where referring assembly came from, but that operation has failed (reason: 2(The system cannot find the file specified.)). Please load the referenced assembly into the current database and retry your request.

So I did as it says, I added the System.Windows.Forms first

Create

Assembly [System.Windows.Forms]

From

'C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Windows.Forms.dll'

With

Permission_Set = Unsafe

 

I noticed on the object explorer that the System.Windows.Forms was added with its refereces

 

Now add the ZedGraph

Create

Assembly [ZedGraph]

From

'C:\ZedGraph\ZedGraph.dll'

With

Permission_Set = Unsafe

 

Now back to VS 2005

 

 

And everything goes well.

 

Important: Always add the unsupported assemblies from a query window, using CREATE ASSEMBLY command, do not add them using the Object Explorer, I tried it and it always gives error.

 

I found a great post on dmitryr's blog on how to find the current trust level for your ASP.NET application, it is practical if you are hosting your site on a hosting company as the hosting company can set the trust level for your application in their machine.config file, and set it un-overridable.

Here is how to check the trust level:

Create an aspx page and place a Label:

<%

@ Page Language ="C#" AutoEventWireup ="true" CodeFile ="CheckTrustLevel.aspx.cs" Inherits ="CheckTrustLevel" %>

<!

DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<

html xmlns ="http://www.w3.org/1999/xhtml" >

<

head runat ="server">

< title > Untitled Page </ title >

</

head >

<

body >

< form id ="form1" runat ="server">

< div >

< asp : Label ID ="Label1" runat ="server" Text ="Label"></ asp : Label >

</ div >

</ form >

</

body >

</

html >

 

 

 

In code behind...

 

using

System;

using

System.Data;

using

System.Configuration;

using

System.Collections;

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;

public

partial class CheckTrustLevel : System.Web.UI. Page

{

protected void Page_Load( object sender, EventArgs e)

{

Label1.Text = GetCurrentTrustLevel().ToString();

}

AspNetHostingPermissionLevel GetCurrentTrustLevel()

{

foreach ( AspNetHostingPermissionLevel trustLevel in

new AspNetHostingPermissionLevel [] {

AspNetHostingPermissionLevel .Unrestricted,

AspNetHostingPermissionLevel .High,

AspNetHostingPermissionLevel .Medium,

AspNetHostingPermissionLevel .Low,

AspNetHostingPermissionLevel .Minimal

})

{

try

{

new AspNetHostingPermission (trustLevel).Demand();

}

catch (System.Security. SecurityException )

{

continue ;

}

return trustLevel;

}

return AspNetHostingPermissionLevel .None;

}

}

 

 

Run the page and it will tell you what trust level your application has.

I use a website provided by the mobile phone company to send SMS messages, and charge it to my mobile phone, good to send bulk messages to friends and family.

I thought about using an automated method to send SMS to make it easier, I asked the mobile phone company if they provide something like a WebAPI or SMPP, but they don't.

So... I thought about using their form, and here come the greate HttpWebRequest and HttpWebResponse.

 

First I opened the login page... opened the page source, search for all form fields, login id, password and hidden fields.

Then I opened the Send SMS page... and did the same.

Now writing a test page:

protected void Page_Load( object sender, EventArgs e)

{

// Login Page

Uri uri = new Uri ( "http://WebSite/index.php" );

// Login Form Fields

string data = "mo=login" ;

data +=

"&passwd=password" ;

data +=

"&login=1" ;

// Create a new instance of the CookieContainer

CookieContainer cookieContainer = new CookieContainer ();

if (uri.Scheme == Uri .UriSchemeHttp)

{

// Create an instance of HttpWebRequest

HttpWebRequest request = HttpWebRequest .Create(uri) as HttpWebRequest ;

// Preserve Cookies that have login information

request.CookieContainer = cookieContainer;

// Method = Post

request.Method =

WebRequestMethods . Http .Post;

// Data Length & Content Type

request.ContentLength = data.Length;

request.ContentType =

"application/x-www-form-urlencoded" ;

// Write Data to stream, this will send data to the website but will not fill the CookieContainer

StreamWriter writer = new StreamWriter (request.GetRequestStream());

writer.Write(data);

writer.Close();

// Get Response from website to fill the CookieContainer

request.GetResponse();

}

 

 

// Do the same here, and submitting the preserved cookies

uri =

new Uri ( "http://WebSite/myo/schedulemsg.php" );

data =

"srcMSISDN=" ;

data +=

"&CustomerId=" ;

data +=

"&strRawText1=" ;

data +=

"&pagename=batsms2.php" ;

data +=

"&smsmode=web2sms" ;

data +=

"&dstMSISDN=" ;

data +=

"&requestType=WEB2SMS" ;

data +=

"&source=WEB" ;

data +=

"&message=Messsgae to send" ;

data +=

"&characters=1" ;

data +=

"&coding=0" ;

data +=

"&when=now" ;

data +=

"&schdate=" ;

data +=

"&hh=00" ;

data +=

"&mm=00" ;

data +=

"&send=Send" ;

if (uri.Scheme == Uri .UriSchemeHttp)

{

HttpWebRequest request = HttpWebRequest .Create(uri) as HttpWebRequest ;

// Submit preserved cookies

request.CookieContainer = cookieContainer;

request.Method =

WebRequestMethods . Http .Post;

request.ContentLength = data.Length;

request.ContentType =

"application/x-www-form-urlencoded" ;

StreamWriter writer = new StreamWriter (request.GetRequestStream());

writer.Write(data);

writer.Close();

// Create an instance of the response to check if the message was sent

HttpWebResponse response = request.GetResponse() as HttpWebResponse ;

StreamReader reader = new StreamReader (response.GetResponseStream());

string tmp = reader.ReadToEnd();

response.Close();

if (tmp.IndexOf( "Message was sent successfully !." ) > 0)

Label1.Text =

"Message was sent successfully !." ;

else

{

Label1.Text =

"Confirmation Message was not received." ;

}

}

}

 

It is working :D as expected.

Source: http://blah.winsmarts.com/2006/05/20/loadcontrol-a-usercontrol--and-pass-in-constructor-parameters.aspx

 

The inability of LoadControl to accept Constructor Parameters is a real pain in the donkey. This post tells you how to get around that hella annoying issue.

The awesome thing about ServerControls in ASP.NET is that you can instantiate them via a constructor, and hence offer a programming model similar to windows forms user controls. Unfortunately, you can't apply the same concept to UserControls because they are really mini pages within themselves. So you are limited to calling something like -

LoadControl("WebUserControl.ascx") ;

Wouldn't it be nice if you could instead do ...

LoadControl("WebUserControl.ascx",constructorparameter1, constructorparameter2, constructorparameter3 ...) ;

So say for instance, it would be nice if the following code would work -

Control toAdd = LoadControl( "WebUserControl.ascx" , "Sahil Malik" ,5) ;
PlaceHolder1.Controls.Add(toAdd) ;

Note: There is a new overload new in .NET 2.0 which takes the signature LoadControl(Type,object[]), which is very similar to the above. But it is frequently problematic in ASP.NET 2.0 to refer to a user control in a strongly typed manner.

Well, here is how you'd make it work.

1. First of all write the user control (Duhh!!). My user control has a label on it called Label1, and it has the following code-behind.

public partial class WebUserControl : System.Web.UI.UserControl
{
    public WebUserControl()
    {
    }

    public WebUserControl(string labelText, int howManyTimes)
    {
        System.Text.StringBuilder sb = new System.Text.StringBuilder() ;
        for (int i = 1; i <= howManyTimes; i++)
        {
            sb.Append(labelText) ;
            sb.Append("<br>") ;
        }
        Label1.Text = sb.ToString() ;
    }
}

As you can see, I am simply appending the same text over and over again. Note that it is important to explicitly create a default public constructor (i.e. one without parameters) or you'd confuse the ASP.NET runtime.

2. Step #2 is to add the following private method to your default.aspx, or add it as a protected method to the base class of all your pages, or a static method that can somehow access your page object. In my case I kept things simple and added a private method to my default.aspx.

private UserControl LoadControl(string UserControlPath, params object[] constructorParameters)
{       
    List<Type> constParamTypes = new List<Type>() ;
    foreach (object constParam in constructorParameters)
    {
        constParamTypes.Add(constParam.GetType()) ;
    }

    UserControl ctl = Page.LoadControl(UserControlPath) as UserControl;

    // Find the relevant constructor
    ConstructorInfo constructor = ctl.GetType().BaseType.GetConstructor(constParamTypes.ToArray()) ;

    //And then call the relevant constructor
    if (constructor == null)
    {
        throw new MemberAccessException("The requested constructor was not found on : " + ctl.GetType().BaseType.ToString()) ;
    }
    else
    {
        constructor.Invoke(ctl,constructorParameters) ;
    }

    // Finally return the fully initialized UC
    return ctl;
}

3. And finally, add the following to the Page_Load (or any other suitable place) of your default.aspx -

protected void Page_Load(object sender, EventArgs e)
{
    Control toAdd = LoadControl("WebUserControl.ascx","Sahil Malik",5) ;
    PlaceHolder1.Controls.Add(toAdd) ;
}