Thursday, 2 January 2014

How to use view state in asp net / how to maintain view state in asp.net

Posted on 09:10 in
Introduction:
This article is helps to how to get values from database in datatable formats using asp.net. Assign and get the viewstate values, Button click events then we bind the gridview after postback.
Designing Page (Source view): 
<!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 id="Head1" runat="server">
<title>How to maintain Datatable in viewstate using ASP.NET</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Button ID="btnviewstates" OnClick="btnviewstate_Click" runat="server" Text="Maintain viewstate in Datatable" />
<asp:GridView ID="grvOutput" runat="server" AutoGenerateColumns="true">
</asp:GridView>
</div>
</form>
</body>
</html>

VB.NET:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not Page.IsPostBack Then
            Dim dtTemp As New DataTable
            Dim con As New SqlConnection("server=192.168.1.100;uid=sa;pwd=sa123;database=asp_dotnet")
            con.Open()
            Dim cmd As New SqlCommand("SELECT b.name,a.subject,a.mark FROM studentmarkdetails a JOIN studentdetails b ON b.id=a.id", con)
            Dim da As New SqlDataAdapter(cmd)
            da.Fill(dtTemp)
            con.Close()
            ViewState("StudentInformation") = dtTemp
        End If
End Sub

Protected Sub btnviewstate_Click(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim dtTemp As DataTable = ViewState("StudentInformation")
        grvOutput.DataSource = dtTemp
        grvOutput.DataBind()
End Sub
C#.NET:
protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
               DataTable dtTemp = new DataTable();
            SqlConnection con = new SqlConnection("server=192.168.1.100;uid=sa;pwd=sa123;database=asp_dotnet");
            con.Open();
            SqlCommand cmd = new SqlCommand("SELECT b.name,a.subject,a.mark FROM studentmarkdetails a JOIN studentdetails b ON b.id=a.id", con);
            SqlDataAdapter da =new SqlDataAdapter(cmd);
            da.Fill(dtTemp);
            con.Close();
            ViewState["StudentInformation"] = dtTemp;
          
            }
}
protected void btnviewstate_Click(object sender, EventArgs e)
        {
            DataTable dtTemp = (DataTable) ViewState["StudentInformation"];
             grvOutput.DataSource = dtTemp;
             grvOutput.DataBind();
}
Demo:

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