c# - Error when paging in GridView -
i have gridview 2 columns. first shows date , second, year of date in first column. far works when change page, web fails message: "object reference not set instance of object."
this code:
test.aspx
<%@ page language="c#" autoeventwireup="true" codefile="test.aspx.cs" inherits="qq_site_test" %> <!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 runat="server"> <title>test</title> </head> <body> <form id="form1" runat="server"> <div> <asp:gridview id="gridview1" runat="server" allowpaging="true" pagesize="5" allowsorting="true" autogeneratecolumns="false" enablemodelvalidation="true" onrowcreated="gridview1_rowcreated" onpageindexchanged="gridview1_pageindexchanged" onpageindexchanging="gridview1_pageindexchanging"> <columns> <asp:commandfield showselectbutton="true" /> <asp:commandfield showdeletebutton="true" /> <asp:boundfield datafield="creationdate" headertext="creationdate" sortexpression="creationdate" /> <asp:templatefield headertext="year"> <itemtemplate> <asp:textbox id="textbox1" runat="server" readonly="true"></asp:textbox> </itemtemplate> </asp:templatefield> </columns> </asp:gridview> </div> </form> </body> </html> test.aspx.cs
using system; using system.collections.generic; using system.web; using system.web.ui; using system.web.ui.webcontrols; using system.data.odbc; using system.data; public partial class qq_site_test : system.web.ui.page { static dataset ds; protected void page_load(object sender, eventargs e) { if (!page.ispostback) { string connectionstring = "dsn=kitchenmaster.es.qq-site;"; string sqlquery = "select * tblsystems id < 100"; ds = new dataset(); odbcconnection connection = new odbcconnection(connectionstring); odbccommand command = new odbccommand(sqlquery, connection); odbcdataadapter adapter = new odbcdataadapter(command); try { adapter.fill(ds); gridview1.datasource = ds; gridview1.databind(); } catch (system.exception ex) { response.write(ex.message); } { if (connection.state == connectionstate.open) connection.close(); } } } protected void gridview1_rowcreated(object sender, gridviewroweventargs e) { if (e.row.rowtype == datacontrolrowtype.datarow) { try { datetime dt = (datetime)databinder.eval(e.row.dataitem, "creationdate"); e.row.cells[getcolumnbyid("year")].text = dt.year.tostring(); } catch (system.exception ex) { response.write(ex.message); } } } protected int getcolumnbyid(string columnname) { foreach (datacontrolfield column in gridview1.columns) { if (column.headertext == columnname) return gridview1.columns.indexof(column); } return -1; } protected void gridview1_pageindexchanged(object sender, eventargs e) { gridview1.selectedindex = -1; } protected void gridview1_pageindexchanging(object sender, gridviewpageeventargs e) { try { if (e.newpageindex != -1) { gridview1.pageindex = e.newpageindex; gridview1.datasource = ds; gridview1.databind(); } } catch (system.exception ex) { response.write(ex.message); } } } can me?
this line of code
gridview1.datasource = ds; is getting error.
when gridview1_pageindexchanging event called, have not yet set value ds. part in code in page_load event, , when it's not postback.