XMLReader Problem

[Ben]

Hi,

I'm just moving to VB.NET and I'm trying to load a recordset intoan XMLReader and loop through the records. When I use the.ReadElementString() method to get the next 'record' if it hasreached the last record (eof) it fails with "Invalid attempt toread when reader is closed". It doesn't seem capable of findingthis out until the error has occured though (Readstate isinteractive prior to the failure and EOF is false.)

Is this limited information enough for anyone to tell me whereI'm going wrong ? (currently as I'm in the early stages I haveif err.number = 5 then err.clear which is a bit crap so ...)

Thanks,

Ben.

[Christoph Schittko [MVP]]

How are you looping through the reader?

Are you checking the return value from the call to the Read method?

While reader.Read()

' do stuff ...

End While

--
HTH
Christoph Schittko [MVP, XmlInsider]
Software Architect, .NET Mentor
"Ben" <gr*********@hotmail.com> wrote in message
news:Os*************@TK2MSFTNGP11.phx.gbl...
Hi,

I'm just moving to VB.NET and I'm trying to load a recordset into an
XMLReader and loop through the records. When I use the .ReadElementString()
method to get the next 'record' if it has reached the last record (eof) it
fails with "Invalid attempt to read when reader is closed". It doesn't seem
capable of finding this out until the error has occured though (Readstate is
interactive prior to the failure and EOF is false.)

Is this limited information enough for anyone to tell me where I'm going
wrong ? (currently as I'm in the early stages I have if err.number = 5 then
err.clear which is a bit crap so ...)

Thanks,

Ben.

[Anandraj]

Hi Ben,
Even I am facing the Same Problem. I am getting three records without Root
Element. I am able to read the values to the End After the End It saying the
same error like "Invalid attempt to read when reader is closed". Any thing
we are doing wrong. Please reply me if you have found out the answer.

Thanks
Anandraj.A.

"Christoph Schittko [MVP]" <ch********************@austin.rr.com> wrote in
message news:#v**************@tk2msftngp13.phx.gbl...

How are you looping through the reader?

Are you checking the return value from the call to the Read method?

While reader.Read()

' do stuff ...

End While

--
HTH
Christoph Schittko [MVP, XmlInsider]
Software Architect, .NET Mentor
"Ben" <gr*********@hotmail.com> wrote in message
news:Os*************@TK2MSFTNGP11.phx.gbl...
Hi,

I'm just moving to VB.NET and I'm trying to load a recordset into an
XMLReader and loop through the records. When I use the ..ReadElementString() method to get the next 'record' if it has reached the last record (eof) it
fails with "Invalid attempt to read when reader is closed". It doesn't seem capable of finding this out until the error has occured though (Readstate is interactive prior to the failure and EOF is false.)

Is this limited information enough for anyone to tell me where I'm going
wrong ? (currently as I'm in the early stages I have if err.number = 5 then err.clear which is a bit crap so ...)

Thanks,

Ben.

[Oleg Tkachenko]

Anandraj wrote:

Even I am facing the Same Problem. I am getting three records without Root
Element. I am able to read the values to the End After the End It saying the
same error like "Invalid attempt to read when reader is closed". Any thing
we are doing wrong. Please reply me if you have found out the answer.

It's not clear what do you mean. Show us some code.
Basically it's your responsibility not to call XmlReader's methods when
there is no more input to read.
--
Oleg Tkachenko
http://www.tkachenko.com/blog
Multiconn Technologies, Israel

[Anandraj]

Hi Oleg,
Here is the detailed description.
I am using only one method to access the Database where the output is XML. I
want to to return the XML to the Client Component. so my code will go like
this below.
XmlReader XmlRdr=null;

... SQL Statement

XmlRdr=Cmd.ExecuteXmlReader();

....

return XmlRdr;

I have read we have to close the XMLReader Otherwise it will create problem.

http://msdn.microsoft.com/library/de...us/cpguide/htm
l/cpconObtainingDataAsXMLFromSQLServer.asp

So Where I have to close the Reader ? I am calling this Method in my Client
Component. I am getting the Exception only in the client Component.

If I put the same code in the Component where the Database Accessing is
Happpening it is working fine.

Please give Suggestions

Thanks

Anandraj.A.

"Oleg Tkachenko" <oleg@no_!spam!_please!tkachenko.com> wrote in message
news:uc**************@TK2MSFTNGP11.phx.gbl...

Anandraj wrote:

Even I am facing the Same Problem. I am getting three records without Root Element. I am able to read the values to the End After the End It saying the same error like "Invalid attempt to read when reader is closed". Any thing we are doing wrong. Please reply me if you have found out the answer.

It's not clear what do you mean. Show us some code.
Basically it's your responsibility not to call XmlReader's methods when
there is no more input to read.
--
Oleg Tkachenko
http://www.tkachenko.com/blog
Multiconn Technologies, Israel

[Oleg Tkachenko]

Anandraj wrote:

So Where I have to close the Reader ? I am calling this Method in my Client
Component. I am getting the Exception only in the client Component.

So am I right that you pass XmlReader client side, read XML from it
successfully and then having exception on Close() method? What's the
exception exactly looks like (along with stack trace, please)?

--
Oleg Tkachenko
XmlInsider
http://blog.tkachenko.com

[Anandraj]

Hi Oleg,
My Component Code goes like htis.
public class WM_Helper

{

public WM_Helper() {}

public static XmlReader GetXMLSet(string SPName)

{

// Creating Connection and Command

XmlReader XmlRdr=null;

string ConString=ConfigurationSettings.AppSettings["ConnectionString"];

SqlConnection Con=new SqlConnection(ConString);

SqlCommand Cmd=new SqlCommand(SPName,Con);

Cmd.CommandType=CommandType.StoredProcedure;

try

{

Con.Open();

XmlRdr=Cmd.ExecuteXmlReader();

}

catch

{

throw new Exception(" Error while executing " + SPName);

}

finally

{

//Disposing the Objects

Con.Dispose();

Cmd.Parameters.Clear();

Cmd.Dispose();

}

return XmlRdr;

}

}

My client code is like this

//try

//{

XmlReader red=WM_Helper.GetXMLSet("GetStatusList");

while(red.Read())

{

}

//}

//catch(Exception Ex)

//{

// string str=Ex.Message;

//}

Exception is "Invalid attempt to Read when reader is closed."

Stack Trace is
Invalid attempt to Read when reader is closed.
at System.Data.SqlClient.SqlDataReader.Read()
at System.Data.SqlClient.SqlStream.Read(Byte[] buffer, Int32 offset, Int32
count)
at System.Xml.XmlStreamReader.Read(Byte[] data, Int32 offset, Int32
length)
at System.Xml.XmlScanner.Read()
at System.Xml.XmlScanner.ScanContent()
at System.Xml.XmlTextReader.ParseBeginTagExpandCharEn tities()
at System.Xml.XmlTextReader.Read()
at MDB.WebForm1.Button7_Click(Object sender, EventArgs e) in
c:\inetpub\wwwroot\mdb\webform1.aspx.cs:line 175
at System.Web.UI.WebControls.Button.OnClick(EventArgs e)
at
System.Web.UI.WebControls.Button.System.Web.UI.IPo stBackEventHandler.RaisePo
stBackEvent(String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(IPostBackEve ntHandler
sourceControl, String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(NameValueCol lection postData)
at System.Web.UI.Page.ProcessRequestMain()

Hope this will help you.

Thanks

Anandraj.A.

"Oleg Tkachenko" <oleg@NO!SPAM!PLEASEtkachenko.com> wrote in message
news:Ox**************@TK2MSFTNGP10.phx.gbl...

Anandraj wrote:

So Where I have to close the Reader ? I am calling this Method in my Client Component. I am getting the Exception only in the client Component.

So am I right that you pass XmlReader client side, read XML from it
successfully and then having exception on Close() method? What's the
exception exactly looks like (along with stack trace, please)?

--
Oleg Tkachenko
XmlInsider
http://blog.tkachenko.com

[Oleg Tkachenko]

Anandraj wrote:

Con.Open();

XmlRdr=Cmd.ExecuteXmlReader();

}

catch

{

throw new Exception(" Error while executing " + SPName);

}

finally

{

//Disposing the Objects

Con.Dispose();

Cmd.Parameters.Clear();

Cmd.Dispose();

This looks suspicious to me. You are creating XmlReader, but closing
connection and command, which provides data XmlReader is supposed to read.
--
Oleg Tkachenko
XmlInsider
http://blog.tkachenko.com

[Anandraj]

Actually I want to write a Common Component for Where Input is Empty and
Output is XML.Usually for Master Datas.
So How can we do this? Here the SP will return the XMLReader as Output from
there I have to get the Different XML in diffrent Client and then I have to
Parse and Show it to the User.
Any Idea to Implement will be help for me.

Thanks
Anandraj.A.

"Oleg Tkachenko" <oleg@NO!SPAM!PLEASEtkachenko.com> wrote in message
news:OC**************@TK2MSFTNGP11.phx.gbl...

Anandraj wrote:

Con.Open();

XmlRdr=Cmd.ExecuteXmlReader();

}

catch

{

throw new Exception(" Error while executing " + SPName);

}

finally

{

//Disposing the Objects

Con.Dispose();

Cmd.Parameters.Clear();

Cmd.Dispose();

This looks suspicious to me. You are creating XmlReader, but closing
connection and command, which provides data XmlReader is supposed to read.
--
Oleg Tkachenko
XmlInsider
http://blog.tkachenko.com

[Jack]

why r u not thinking of DATASET ??
"Anandraj" <a_*************@yahoo.com> wrote in message
news:OQ**************@tk2msftngp13.phx.gbl...

Actually I want to write a Common Component for Where Input is Empty and
Output is XML.Usually for Master Datas.
So How can we do this? Here the SP will return the XMLReader as Output from there I have to get the Different XML in diffrent Client and then I have to Parse and Show it to the User.
Any Idea to Implement will be help for me.

Thanks
Anandraj.A.

"Oleg Tkachenko" <oleg@NO!SPAM!PLEASEtkachenko.com> wrote in message
news:OC**************@TK2MSFTNGP11.phx.gbl...

Anandraj wrote:

Con.Open();

XmlRdr=Cmd.ExecuteXmlReader();

}

catch

{

throw new Exception(" Error while executing " + SPName);

}

finally

{

//Disposing the Objects

Con.Dispose();

Cmd.Parameters.Clear();

Cmd.Dispose();

This looks suspicious to me. You are creating XmlReader, but closing
connection and command, which provides data XmlReader is supposed to read. --
Oleg Tkachenko
XmlInsider
http://blog.tkachenko.com

[Anandraj]

Hi Jack,
We are not using the Dataset at all. We are store the data in the Objects
and Sending to the clinet similar to Javabeans in Java.
Is there any way to do that using the XMLReader. It will help ful to know
the reason and Answer for the Question.
anand
"Jack" <ja**@somewhere.com> wrote in message
news:#m**************@TK2MSFTNGP09.phx.gbl...

why r u not thinking of DATASET ??
"Anandraj" <a_*************@yahoo.com> wrote in message
news:OQ**************@tk2msftngp13.phx.gbl...

Actually I want to write a Common Component for Where Input is Empty and
Output is XML.Usually for Master Datas.
So How can we do this? Here the SP will return the XMLReader as Output

from

there I have to get the Different XML in diffrent Client and then I have

to

Parse and Show it to the User.
Any Idea to Implement will be help for me.

Thanks
Anandraj.A.

"Oleg Tkachenko" <oleg@NO!SPAM!PLEASEtkachenko.com> wrote in message
news:OC**************@TK2MSFTNGP11.phx.gbl...

Anandraj wrote:
> Con.Open();
>
> XmlRdr=Cmd.ExecuteXmlReader();
>
> }
>
> catch
>
> {
>
> throw new Exception(" Error while executing " + SPName);
>
> }
>
> finally
>
> {
>
> //Disposing the Objects
>
> Con.Dispose();
>
> Cmd.Parameters.Clear();
>
> Cmd.Dispose();

This looks suspicious to me. You are creating XmlReader, but closing
connection and command, which provides data XmlReader is supposed to read. --
Oleg Tkachenko
XmlInsider
http://blog.tkachenko.com

[Jack]

is this win app????


"Anandraj" <a_*************@yahoo.com> wrote in message
news:uZ**************@TK2MSFTNGP09.phx.gbl...

Hi Jack,
We are not using the Dataset at all. We are store the data in the Objects
and Sending to the clinet similar to Javabeans in Java.
Is there any way to do that using the XMLReader. It will help ful to know
the reason and Answer for the Question.
anand
"Jack" <ja**@somewhere.com> wrote in message
news:#m**************@TK2MSFTNGP09.phx.gbl...

why r u not thinking of DATASET ??
"Anandraj" <a_*************@yahoo.com> wrote in message
news:OQ**************@tk2msftngp13.phx.gbl...

Actually I want to write a Common Component for Where Input is Empty and Output is XML.Usually for Master Datas.
So How can we do this? Here the SP will return the XMLReader as Output

from

there I have to get the Different XML in diffrent Client and then I

have to

Parse and Show it to the User.
Any Idea to Implement will be help for me.

Thanks
Anandraj.A.

"Oleg Tkachenko" <oleg@NO!SPAM!PLEASEtkachenko.com> wrote in message
news:OC**************@TK2MSFTNGP11.phx.gbl...
> Anandraj wrote:
>
>
> > Con.Open();
> >
> > XmlRdr=Cmd.ExecuteXmlReader();
> >
> > }
> >
> > catch
> >
> > {
> >
> > throw new Exception(" Error while executing " + SPName);
> >
> > }
> >
> > finally
> >
> > {
> >
> > //Disposing the Objects
> >
> > Con.Dispose();
> >
> > Cmd.Parameters.Clear();
> >
> > Cmd.Dispose();
>
> This looks suspicious to me. You are creating XmlReader, but closing
> connection and command, which provides data XmlReader is supposed to

read.

> --
> Oleg Tkachenko
> XmlInsider
> http://blog.tkachenko.com