MBR IT/.NET 247 : Persisting datasets using viewstates and xml on ASPFriends.com 'aspngdatagridrepeaterdatalist' list

Persisting datasets using viewstates and xml

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This message was discovered on ASPFriends.com 'aspngdatagridrepeaterdatalist' list.

I am trying to use viewstates and xml to persist datasets instead of sessions, however, I get a NULL error when I try to read back the XML string.

Have I done something wrong ??? Here's part of my page_load() method

**************
if (ViewState["Hello"] == null) {
ds = new DataSet();
oleDa.Fill(ds, "customers");
string myXml = ds.GetXml();
//put xml from dataset into ViewState
ViewState["Hello"] = myXml;
} else {
//get xml back from ViewState
string vxml = ViewState["Hello"].ToString();
StringReader sr = new StringReader(vxml);
//read in XML from stream
ds.ReadXml(sr);
}
if (!IsPostBack)
{
MyDataGrid.DataSource = dv;
MyDataGrid.DataBind();
}
*******

Can someone help !!

CHEERS !!

Sum Pun

Reply to this message...

Alex Lowe

Have you checked out this article -
http://www.aspfree.com/authors/stephen_rylander/Persist.aspx?

Alex - AspFriends.com Moderation Team
Microsoft MVP - ASP.NET

***********************************************************
Translate C# code to VB.NET code at
http://aspalliance.com/aldotnet/examples/translate.aspx
***********************************************************

-----Original Message-----
From: Click here to reveal e-mail address [mailto:Click here to reveal e-mail address]
Sent: Sunday, August 11, 2002 7:17 AM
To: aspngDataGridRepeaterDatalist
Subject: [aspngdatagridrepeaterdatalist] Persisting datasets using
viewstates and xml

I am trying to use viewstates and xml to persist datasets instead of
sessions, however, I get a NULL error when I try to read back the XML
string.

Have I done something wrong ??? Here's part of my page_load() method

**************
if (ViewState["Hello"] == null) {
ds = new DataSet();
oleDa.Fill(ds, "customers");
string myXml = ds.GetXml();
//put xml from dataset into ViewState
ViewState["Hello"] = myXml;
} else {
//get xml back from ViewState
string vxml = ViewState["Hello"].ToString();
StringReader sr = new StringReader(vxml);
//read in XML from stream
ds.ReadXml(sr);
}
if (!IsPostBack)
{
MyDataGrid.DataSource = dv;
MyDataGrid.DataBind();
}
*******

Can someone help !!

CHEERS !!

Sum Pun
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YOUR ID |
http://www.aspfriends.com/aspfriends/aspngdatagridrepeaterdatalist.asp =
JOIN/QUIT

Reply to this message...

Doug J. Nelson

In the code example you posted,=20

if (ViewState["Hello"] =3D=3D null) {=20
ds =3D new DataSet();=20
oleDa.Fill(ds, "customers");=20
string myXml =3D ds.GetXml();=20
//put xml from dataset into ViewState=20
ViewState["Hello"] =3D myXml;=20
} else {=20
//get xml back from ViewState=20
string vxml =3D ViewState["Hello"].ToString();=20
StringReader sr =3D new StringReader(vxml); =20
//read in XML from stream=20
ds.ReadXml(sr);=20
}

Declare ds outside of the if statement when you get to the else
statement, ds is undeclared.

ds =3D new DataSet();
if(ViewState["Hello"] =3D=3D null)
{
oleDa.Fill(ds, "customers");=20
string myXml =3D ds.GetXml();=20
//put xml from dataset into ViewState=20
ViewState["Hello"] =3D myXml;=20
}
else
{
//get xml back from ViewState=20
string vxml =3D ViewState["Hello"].ToString();=20
StringReader sr =3D new StringReader(vxml); =20
//read in XML from stream=20
ds.ReadXml(sr);=20
}

Doug Nelson
SynApp north
305 Arch St
Cloquet, MN 55720
(218) 878 - 2015=20
(218) 878 - 2019 fax

Reply to this message...

	System.Data.DataSet
	System.IO.StringReader

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