ASPX using C# : System.InvalidCastException: Specified cast is not valid - C# Discussion Boards

Re: ASPX using C# : Exception Details: System.Web.HttpException: A page can have only one server-side Form tag.

15-Dec-05 7:42

When I run my ASPX page I receive the following error message:

Server Error in '/test' Application.
--------------------------------------------------------------------------------

A page can have only one server-side Form tag.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: A page can have only one server-side Form tag.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[HttpException (0x80004005): A page can have only one server-side Form tag.]
System.Web.UI.Page.OnFormRender(HtmlTextWriter writer, String formUniqueID)
System.Web.UI.HtmlControls.HtmlForm.RenderChildren(HtmlTextWriter writer)
System.Web.UI.HtmlControls.HtmlContainerControl.Render(HtmlTextWriter writer)
System.Web.UI.HtmlControls.HtmlForm.Render(HtmlTextWriter output)
System.Web.UI.Control.RenderControl(HtmlTextWriter writer)
System.Web.UI.Control.RenderChildren(HtmlTextWriter writer)
System.Web.UI.HtmlControls.HtmlForm.RenderChildren(HtmlTextWriter writer)
System.Web.UI.HtmlControls.HtmlContainerControl.Render(HtmlTextWriter writer)
System.Web.UI.HtmlControls.HtmlForm.Render(HtmlTextWriter output)
System.Web.UI.Control.RenderControl(HtmlTextWriter writer)
System.Web.UI.Control.RenderChildren(HtmlTextWriter writer)
System.Web.UI.Control.Render(HtmlTextWriter writer)
System.Web.UI.Control.RenderControl(HtmlTextWriter writer)
System.Web.UI.Page.ProcessRequestMain()

I only have one form tag throughout the whole project so I really don't understand what it's complaining about.
Thanks! Big Grin | :-D

Jane

enjoycrack15-Dec-05 7:56

Re: ASPX using C# : Exception Details: System.Web.HttpException: A page can have only one server-side Form tag.

15-Dec-05 7:56

Hi there,

IMO, the error is describing pretty well. You might have 2 forms with the runat='server' attribute. Can you post the form's code here?

<< >>

jmfekete15-Dec-05 8:06

Re: ASPX using C# : Exception Details: System.Web.HttpException: A page can have only one server-side Form tag.

15-Dec-05 8:06

Do you think it's talking about the two "runat" I have in the following code:

<asp:datagrid id="_gdl
" width="100%"
="" runat="server" allowcustompaging="true" allowpaging="true" onpageindexchanged="Grid_Change" pagesize="10
">

If so, then should I delete " Runat="server" "?
Thanks!

enjoycrack15-Dec-05 8:09

Re: ASPX using C# : Exception Details: System.Web.HttpException: A page can have only one server-side Form tag.

15-Dec-05 8:09

Are you using master page??

<< >>

jmfekete15-Dec-05 8:25

Composite Pattern and Generics

15-Dec-05 8:25

Hmm. If I new what master page was I could tell you. When I deleted " Runat="server" " I didn't receive the error message anymore. Now I have initialize _gdl.VirtualItemCount somewhere because it doesn't like that.
As far as I know VirtualItemCount is a predefined function. When I place my cursor over the function, the tool tip says "Gets or sets the virtual number of items in the System.Web.UI.WebControls.Datagrid control when custom paging is used".

This is the first chunk of code I have after defining the namespace:

public class DataGridPage : Page
{
private int _startIndex=0;
protected DataGrid _gdl;

protected void Page_Load(object Src, EventArgs e)
{
if (!IsPostBack)
{
_gdl.VirtualItemCount = GetItemCount();
_startIndex = _gdl.VirtualItemCount-_gdl.PageSize;
BindGrid();
}
}

Thanks!

Jane

RogerRabbit7815-Dec-05 7:20

RogerRabbit78

15-Dec-05 7:20

Hi,

I have a little Generic problem.
Look a this very simplified Composite Pattern:

public abstract class BaseClass
{
}

public class Leaf
{
}

public class LeafA : Leaf
{
}

public class LeafB : Leaf
{
}

public class Composite<TChild> where TChild : BaseClass
{
  private List<TChild> _children = new List<TChild>();
  public List<TChild> Children { get { return _children;}}
}

Now in the main program I create a sample tree structure:

Composite<BaseClass> root = new Composite<BaseClass>();

root.Children.Add(new LeafB());
root.Children.Add(new LeafA());


Composite<LeafA> comp = new Composite<LeafA>();
comp.Children.Add(new LeafA());
comp.Children.Add(new LeafA());

root.Children.Add(comp);

comp = new Composite<LeafB>();
comp.Children.Add(new LeafB());
comp.Children.Add(new LeafB());

root.Children.Add(comp);

How i can check, if the childnode is a Composite ?
I ever get back a null

foreach (BaseClass b in root.Children)
{
  // test if Leaf
  if (b is Leaf)
  {
  }
  // else it must be Composite
  else
  {
    Composite<BaseClass> child = (b as Composite<BaseClass>); // child is null after this cast
  }
}

How I can solve this ?

thx for your help

Roger

ASPX using C# : System.InvalidCastException: Specified cast is not valid

jmfekete15-Dec-05 6:57

Re: ASPX using C# : System.InvalidCastException: Specified cast is not valid

15-Dec-05 6:57

When running my aspx page that uses C# programming I receive the following error message:
Server Error in '/test' Application.
--------------------------------------------------------------------------------

Specified cast is not valid.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidCastException: Specified cast is not valid.

Source Error:

Line 50: {
Line 51: conn.Open();
Line 52: count = (int)cmd.ExecuteScalar();
Line 53: }
Line 54: finally { conn.Dispose(); }

Source File: c:\inetpub\wwwroot\test\test.aspx.cs Line: 52

Stack Trace:

[InvalidCastException: Specified cast is not valid.]
test.DataGridPage.GetItemCount() in c:\inetpub\wwwroot\test\test.aspx.cs:52
test.DataGridPage.Page_Load(Object Src, EventArgs e) in c:\inetpub\wwwroot\test\test.aspx.cs:35
System.Web.UI.Control.OnLoad(EventArgs e)
System.Web.UI.Control.LoadRecursive()
System.Web.UI.Page.ProcessRequestMain()

What can I do so that I won't get this message and can finally see if the data is being loaded into my ASPX page properly? I checked on Microsoft's website to see what it means but it's like reading stereo instructions.
Thanks!

Jane

enjoycrack15-Dec-05 7:00

Re: ASPX using C# : System.InvalidCastException: Specified cast is not valid

15-Dec-05 7:00

Hi there,

IMO, try to delete all file in debug folder and rebuild then the project....

Gud luke

<< >>

jmfekete15-Dec-05 7:25

Re: ASPX using C# : System.InvalidCastException: Specified cast is not valid

15-Dec-05 7:25

Thanks for the advice but that didn't work. I'm grabbing data from my local SQL server and I just want to post it. Do you need my code?

Jane

jmfekete15-Dec-05 7:30

Re: ASPX using C# : System.InvalidCastException: Specified cast is not valid

15-Dec-05 7:30

Nevermind, someone else's solution eliminated the problem.
Thanks for your help!!

Jane

enjoycrack15-Dec-05 7:52

Re: ASPX using C# : System.InvalidCastException: Specified cast is not valid

15-Dec-05 7:52

Happy coding ... Rose | [Rose]

<< >>

chinky singh15-Dec-05 7:22

chinky singh

15-Dec-05 7:22

change the code on line 52:

count = (int)cmd.ExecuteScalar();
to
count = Convert.ToInt32(cmd.ExecuteScalar());

Re: ASPX using C# : System.InvalidCastException: Specified cast is not valid

jmfekete15-Dec-05 7:29

A Static class Serialization problem

15-Dec-05 7:29

Woohooo! That eliminated the error message. Thank you very much! Now I just have to get past another one.

Jane

HolyGrandFather15-Dec-05 6:45

15-Dec-05 6:45

Hi..

i have a Class, that has 3 DataMembers, all three are Static...
whenever i try to Serialize her, the output XML is EMPTY!
Please do help,

Here is the Class code, and Xml Serializer code...

The Class
-------

using System;
using System.IO;
using System.Xml;
using System.Runtime.Serialization.Formatters.Binary;
using System.Xml.Serialization ;

namespace ShipurSherut
{
[Serializable]
public class AppSettings
{
public static String Merhav;
public static String Yeud;
public static String ServerAddress;

static AppSettings()
{

}
}
}

The Xml Serializer:
--------------

public static void ToXml(Object objToXml,string filePath,bool includeNameSpace)
{
StreamWriter stWriter=null;
XmlSerializer xmlSerializer;
try
{
xmlSerializer = new XmlSerializer(objToXml.GetType());
stWriter = new StreamWriter(filePath);
if (!includeNameSpace)
{
System.Xml.Serialization.XmlSerializerNamespaces xs= new XmlSerializerNamespaces();
xs.Add("","");//To remove namespace and any other inline information tag
xmlSerializer.Serialize(stWriter, objToXml,xs);
}
else
{
xmlSerializer.Serialize(stWriter, objToXml);
}
}
catch(Exception exception)
{
throw exception;
}
finally
{
if(stWriter!=null) stWriter.Close();
}
}

Guffa15-Dec-05 11:39

15-Dec-05 11:39

If you only have static fields, there is no data in the object, so there is nothing to serialize.

---
b { font-weight: normal; }

HolyGrandFather16-Dec-05 8:59

16-Dec-05 8:59

So, Maybe i missunderstood the whole meaning of Static.. i thought a claasic datamembers , let's me , save my data at a class, that don't need and instance in order for me to read the data... a sort of public class. that i can approach from every class in my project./

in that case , i wanted to take the data from my xml file( the application settings) and then use it in multiple classes, without havin the need to open instances of the same class , and double my data....

am i missing the propuse of the static class?

Guffa18-Dec-05 0:48

18-Dec-05 0:48

No, that is correct. The static members reside in the class. But you are serializing an object, not the class.

---
b { font-weight: normal; }

HolyGrandFather18-Dec-05 5:27

18-Dec-05 5:27

ok, How can i serialize the class?

Guffa18-Dec-05 22:51

18-Dec-05 22:51

You can't serialize a class, as a class can not be dynamically created.

One way to serialize the static information could be to put the fields in a separate class, and put a static instance of that class in the original class:

public class MyInfo {<br />
string info, moreInfo, excessInfo;<br />
}<br />
<br />
public class MyClass {<br />
static MyInfo info = new MyInfo();<br />
}

Then you can add serialization to the info class, and serialize the static instance.

---
b { font-weight: normal; }

HolyGrandFather19-Dec-05 4:50

Re: Browser closing event

19-Dec-05 4:50

Man, i can't find the words , to express my gratitude...
i'm programming alone, a messy project.
i got no experiance in c#, and i can't ask anyone i know for help, cause they don't prog... and if they are,, not c#...

anyhow, Thank you... it works FINE! , i did exactly what you told me...

Bye - Yosi! Smile | :)

Browser closing event

chinky singh15-Dec-05 5:51

chinky singh

15-Dec-05 5:51

Hi All

I am using javascript to catch the browser closing event as I have to delete few files if the user closes the browser directly without logging off.

But if the javascript is disabled in the browser of the user, then files will not get deleted.
Is their anyway I can catch the browser closing event in asp.net rather than javascript?

Thanks

albCode15-Dec-05 5:54

albCode

15-Dec-05 5:54

check this link

http://www.codecomments.com/ASP_.NET_Caching/message670221.html

Re: Browser closing event

chinky singh15-Dec-05 6:12

chinky singh

15-Dec-05 6:12

hi Albanian

I did check the link. My Page_Unload event is not invoked at all. Is their anyway I can invoke that.
Using javascript I am able to catch the browser closing but I need some way to do without that.

Re: Browser closing event

Guffa15-Dec-05 11:54