Pass ASP.Net GridView from one page to another page

Question

I want to pass all the gridview value into another page I have one gridview in PatientDetails.aspx page and one button as below

<asp:GridView ID="gvDoctorList" runat="server" AutoGenerateColumns="False" DataSourceID="SqlDataSource1" 
    AllowPaging="True" AllowSorting="True" AutoGenerateEditButton="true" AutoGenerateSelectButton="true"
    AutoGenerateDeleteButton="true" OnSelectedIndexChanged="gvDoctorList_SelectedIndexChanged" OnRowCommand="gvDoctorList_RowCommand">
    <Columns>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:CheckBox runat="server" ID="chk" OnCheckedChanged="chk_CheckedChanged" AutoPostBack="true" />
                <asp:Label runat="server" ID="lblPID" Visible="false" Text='<%# Eval("PatientId") %>'></asp:Label>
                <asp:Button ID="btnSelect" runat="server" Text="Select" CommandName = "Select" />
            </ItemTemplate>
        </asp:TemplateField>

        <asp:BoundField DataField="PatientId" HeaderText="PatientId" SortExpression="PatientId" />
        <asp:BoundField DataField="firstname" HeaderText="firstname" SortExpression="firstname" />
        <asp:BoundField DataField="lastname" HeaderText="lastname" SortExpression="lastname" />                                
        <asp:BoundField DataField="sex" HeaderText="sex" SortExpression="sex" />
    </Columns>
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:MyDatabaseConnectionString %>" 
    SelectCommand="SELECT [PatientId],[firstname], [lastname], [sex] FROM [PatientDetails]"></asp:SqlDataSource>
<asp:Button ID="btnformatric" runat="server" Text="formatric3d" OnClick="btnformatric_Click" OnCommand="btnformatric_Command" />

on codebehind of PatientDetails.aspx is as below

protected void btnformatric_Click(object sender, EventArgs e)
{
    if (gvDoctorList.SelectedRow != null)
    {
        Server.Transfer("Patientstaticformatrix.aspx");
    }
    else
    {
        ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('Please select a row.')", true);
    }
}

Now on the second page name Patientstaticformatrix.aspx the code behind is as below

protected void Page_Load(object sender, EventArgs e)
{
    if (this.Page.PreviousPage != null)
    {
        GridView gvDoctorList = (GridView)this.Page.PreviousPage.FindControl("gvDoctorList");

        GridViewRow selectedRow = gvDoctorList.SelectedRow;
        Response.Write("PatientId: " + selectedRow.Cells[0].Text + "<br />");
        Response.Write("firstname: " + selectedRow.Cells[1].Text + "<br />");
        Response.Write("lastname: " + selectedRow.Cells[2].Text + "<br />");
    }
}

I had debug the code in second page....the value for gvDoctorList is null as well as the selectedRow is showing error of nullreference.

Can you please let me where I am wrong?

Answer 1

As i have seen your previous question also, So i can suggest you one thing, rather than keeping your gridview in session(which is expensive) you can use RowCommand event, and after having button here i don't think you need checkbox or chk_CheckedChanged event, you can pass the PatientID to your next page there you can write query to insert selected row data to your new table.

 <asp:TemplateField>
       <ItemTemplate>
        <asp:CheckBox runat="server" ID="chk" OnCheckedChanged="chk_CheckedChanged"  
         AutoPostBack="true" />
        <asp:Label runat="server" ID="lblPID" Visible="false" Text='<%# Eval("PatientId") %>'> 
       </asp:Label>
      <asp:Button ID="btnSelect" runat="server" Text="Select" CommandArgument='<%# 
       Eval("PatientId") %>' CommandName = "Select" />
      </ItemTemplate>
    </asp:TemplateField>



 protected void gvDoctorList_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            if (e.CommandName == "select")
            {
                int pID = Convert.ToInt32(e.CommandArgument);
                // either put ID in session and check 
                Session["PatientID"] = Convert.ToString(pID);
                Server.Transfer("Patientstaticformatrix.aspx");
            }
        }

On page_Load Event

 protected void Page_Load(object sender, EventArgs e)
    {
         string pID = Convert.ToString(Session["PatientID"]);
            if(!string.IsNullOrEmpty(pID))
            {
              int patientID = Convert.ToInt32(pID);
             //Call Stored procedure which will insert this record with this ID
             // to another table
            }    

    }

Answer 2

Try using Session Variables. You can set the GridView into a Session variable that can then be retreived later so long as the same session is still active.

You can use the following code to set the Session Variable on your first page :

Session["gvDoctorList"] = gvDoctorList;

And then to retreive from the variable on your second page :

GridView gvDoctorList = (GridView)Session["gvDoctorList"];

For more information on Sessions see the MSDN Session State Overview.