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Checkbox in datgridview not refrashing page when checked

I am trying to follow this exemple https://www.aspsnippets.com/Articles/Transfer-Selected-Rows-from-one-GridView-to-Another-in-Asp.net.aspx however my version dose not refreash the page when a checkbox is checked why is that?
Here is my front end code,
<asp:GridView ID="gvPurchases" runat="server" AutoGenerateColumns="false" ShowFooter="true" onrowdatabound="gvPurchases_RowDataBound"
ShowHeaderWhenEmpty="true" AllowPaging="True" OnPageIndexChanging="gridView_PageIndexChanging" DataKeyNames="compras_id"
OnRowCommand="gvPurchases_RowCommand" OnRowEditing="gvPurchases_RowEditing" OnRowCancelingEdit="gvPurchases_RowCancelingEdit"
OnRowUpdating="gvPurchases_RowUpdating" CellPadding="3" AllowUserToResizeColumns="True" PageSize="5" AllowSorting="true" onsorting="gvPurchases_Sorting" GridLines="None" CssClass="mGrid" PagerStyle-CssClass="pgr" AlternatingRowStyle-CssClass="alt">
<PagerSettings Mode="Numeric" />
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:CheckBox ID="chkRow" AutoPostBack="true" EnableViewState="true" runat="server" onclick = "Check_Click(this)" OnCheckedChanged="CheckBox_CheckChanged" />
<%--<asp:CheckBox ID="chkRow" runat="server" />--%>
<asp:ImageButton ImageUrl="~/Images/edit.png" runat="server" CommandName="Edit" ToolTip="Edit" Width="20px" Height="20px"/>
<asp:ImageButton ImageUrl="~/Images/delete.png" runat="server" CommandName="Delete" ToolTip="Delete" Width="20px" Height="20px"/>
</ItemTemplate>
<EditItemTemplate>
<asp:ImageButton ImageUrl="~/Images/save.png" runat="server" CommandName="Update" ToolTip="Update" Width="20px" Height="20px"/>
<asp:ImageButton ImageUrl="~/Images/cancel.png" runat="server" CommandName="Cancel" ToolTip="Cancel" Width="20px" Height="20px"/>
</EditItemTemplate>
<FooterTemplate>
<asp:ImageButton ImageUrl="~/Images/addnew.png" runat="server" CommandName="AddNew" ToolTip="Add New" Width="20px" Height="20px"/>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Compras ID" SortExpression="compras_id">
<ItemTemplate>
<asp:Label DataField="compras_id" ID="lblPurschaseID" CssClass="gridTextbox" Text='<%# Eval("compras_id") %>' runat="server" />
</ItemTemplate>
<%--<EditItemTemplate>
<asp:TextBox CssClass="gridTextbox" ID="txtType" Text='<%# Eval("tipo") %>' runat="server" />
</EditItemTemplate>--%>
<FooterTemplate>
<asp:TextBox CssClass="gridTextbox" ID="txtPurschaseIDFooter" runat="server" />
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Contract Number" >
<ItemTemplate>
<asp:Label DataField="numero_contrato" ID="lblContractNumber" CssClass="gridTextbox" Text='<%# Eval("numero_contrato") %>' runat="server" />
</ItemTemplate>
<EditItemTemplate>
<asp:DropDownList ID="drGridContractID" Runat="server" AutoPostBack="false" OnSelectedIndexChanged="DropDown_SelectedIndexChanged" />
<%-- <asp:TextBox CssClass="gridTextbox" ID="txtSupplier" Text='<%# Eval("nombre_proveedor") %>' runat="server" />--%>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox CssClass="gridTextbox" ID="txtContractNumberFooter" runat="server" />
</FooterTemplate>
</asp:TemplateField>
And here is my backend:
protected void CheckBox_CheckChanged(object sender, EventArgs e)
{
GetData();
SetData();
BindSecondaryGrid();
}
However the page does not refresh when checkbox is checked why is that?

I had to remove onclick = "Check_Click(this)" to fix the proble the onClick is useless.
Change
<asp:CheckBox ID="chkRow" AutoPostBack="true" EnableViewState="true" runat="server" onclick = "Check_Click(this)" OnCheckedChanged="CheckBox_CheckChanged" />
to
<asp:CheckBox ID="chkRow" AutoPostBack="true" EnableViewState="true" runat="server" OnCheckedChanged="CheckBox_CheckChanged" />

Get text box value from grid view Header

I have grid with text box for filter data on header.I have button outside the grid.I am using this gridview for filtering the grid by some columns. When I click on button I want to get value from text box and dropdownlist on codebehind.cs, below is my webform.aspx code of gridview,
<asp:Button ID="btngetLocationDate" runat="server" Text="Get Filtered Data" OnClick="getTextBoxValue"></asp:Button>
<asp:GridView ID="TrackerGrid" runat="server" BackColor="#CCCCCC" AllowPaging="True" AutoGenerateColumns="false">
<AlternatingRowStyle HorizontalAlign="Center" VerticalAlign="Middle" />
<Columns>
<asp:TemplateField HeaderText="User ID" SortExpression="User ID">
<ItemTemplate>
<asp:Label ID="lbluserid" runat="server" Text='<%# Eval("User ID") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Customer Name">
<HeaderTemplate>
Full Name:
<asp:DropDownList ID="ddlfullName" runat="server" AutoPostBack="true" OnSelectedIndexChanged="onselectDropdown">
<asp:ListItem Text="ALL" Value="ALL" Selected="True"></asp:ListItem>
</asp:DropDownList>
</HeaderTemplate>
<ItemTemplate>
<asp:Label ID="lblname" runat="server" Text='<%# Eval("Full Name") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Mobile Number">
<HeaderTemplate>
Mobile Number:
<asp:TextBox ID="txtMobilenumber" runat="server" AutoPostBack="true"></asp:TextBox>
</HeaderTemplate>
<ItemTemplate>
<asp:Label ID="lblmobile" runat="server" Text='<%# Eval("Mobile Phone") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Email Address">
<HeaderTemplate>
Email Id:
<asp:TextBox ID="txtemail" runat="server" AutoPostBack="true"></asp:TextBox>
</HeaderTemplate>
<ItemTemplate>
<asp:Label ID="lblemail" runat="server" Text='<%# Eval("Email ID") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Longitude">
<HeaderTemplate>
<asp:Label ID="lbllng" runat="server" Text="Longitude"></asp:Label>
</HeaderTemplate>
<ItemTemplate>
<asp:Label ID="lbllongi" runat="server" Text='<%# Eval("Longitude") %>' Width="70"></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Lattitude">
<HeaderTemplate>
<asp:Label ID="lbllat" runat="server" Text="Lattitude"></asp:Label>
</HeaderTemplate>
<ItemTemplate>
<asp:Label ID="lbllatti" runat="server" Text='<%# Eval("Lattitude") %>' Width="70"></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Activated On">
<HeaderTemplate>
<asp:Label ID="lbldevices" runat="server" Text="Activated On"></asp:Label></br>
</HeaderTemplate>
<ItemTemplate>
<asp:Label ID="lbldevice" runat="server" Text='<%# Eval("Activated On") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Location DateTime" SortExpression="Location DateTime">
<HeaderTemplate>
<asp:Label ID="Label1" runat="server" Text="Location DateTime"></asp:Label></br>
<asp:Label ID="lblStartDate" runat="server" AssociatedControlID="txtStartDate" Text="Start Date"></asp:Label>
<asp:TextBox ID="txtStartDate" runat="server"></asp:TextBox>
<cc1:calendarextender id="CalendarStartDate" runat="server" format="dd/MM/yyyy" targetcontrolid="txtStartDate" popupbuttonid="imgPopup1"></cc1:calendarextender>
<asp:ImageButton ID="imgPopup1" runat="server" ImageUrl="https://cdn4.iconfinder.com/data/icons/small-n-flat/24/calendar-alt-512.png" Height="20px" Width="30px" />
</br>
<asp:Label ID="lblEndDate" runat="server" Text="End Date" AssociatedControlID="txtEndDate"></asp:Label>
<asp:TextBox ID="txtEndDate" runat="server"></asp:TextBox>
<cc1:calendarextender id="CalendarEndDate" runat="server" format="dd/MM/yyyy" targetcontrolid="txtEndDate" popupbuttonid="imgPopup2"></cc1:calendarextender>
<asp:ImageButton ID="imgPopup2" runat="server" ImageUrl="https://cdn4.iconfinder.com/data/icons/small-n-flat/24/calendar-alt-512.png" Height="20px" Width="30px" />
</HeaderTemplate>
<ItemTemplate>
<asp:Label ID="lblDatetime" runat="server" Text='<%# Eval("Location DateTime") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
and I am getting texbox value in codebehind code.
protected void getTextBoxValue(object sender, EventArgs e)
{
DropDownList ddlfullname = (TrackerGrid.HeaderRow.FindControl("ddlfullName") as DropDownList);
string selectedValue = ddlfullname.SelectedItem.Text;
TextBox mobilenumber = (TrackerGrid.HeaderRow.FindControl("txtMobilenumber") as TextBox);
string mobile = mobilenumber.Text;
TextBox email = TrackerGrid.HeaderRow.FindControl("txtemail") as TextBox;
string emailid = email.Text;
TextBox staloc = TrackerGrid.HeaderRow.FindControl("txtStartDate") as TextBox;
string startlocatdate = staloc.Text;
TextBox endloc = TrackerGrid.HeaderRow.FindControl("txtEndDate") as TextBox;
string endlocadate = endloc.Text;
}
I am getting empty value when I debugging this code.I think my code is correct but how i am not getting value of textboxes, i don't understand. Please help me for solving my issue.
Thanks in advance.

You probably did not wrap the DataBind() of the Gridview inside an IspostBack check. If you do not then the values will be rested by the DataBind instead of being saved with ViewState.
protected void Page_Load(object sender, EventArgs e)
{
//not here
TrackerGrid.DataSource = source;
TrackerGrid.DataBind();
if (IsPostBack == false)
{
//but inside an ispostback check
TrackerGrid.DataSource = source;
TrackerGrid.DataBind();
}
}

Gridview row editing is not working

can anyone tell me what i am missing why my row editing event is not firing.
I am trying to give edit facility in same grid as well as Add new data.
I am able to add new data (new row) but unable to edit existing row for update.
my row editing event is not firing.
<asp:GridView ID="grdHierarchy" runat="server" AllowSorting="True" AutoGenerateColumns="False" CssClass="tableGridBorder" GridLines="None" ShowFooter="True" ShowHeaderWhenEmpty="True" Width="100%" OnRowCommand="grdHierarchy_RowCommand" OnRowDataBound="grdHierarchy_RowDataBound"
OnRowEditing="grdHierarchy_RowEditing">
<AlternatingRowStyle CssClass="AlternateRow" />
<Columns>
<asp:TemplateField HeaderText="Sr.#">
<ItemTemplate>
<asp:Label ID="lblSrNo" runat="server" Text="<%# Container.DataItemIndex + 1 %>"></asp:Label>
</ItemTemplate>
<ItemStyle CssClass="textAlignCenter" />
<HeaderStyle CssClass="textAlignCenter" />
</asp:TemplateField>
<asp:TemplateField HeaderText="Name">
<ItemTemplate>
<asp:Label ID="lblName" runat="server" Text='<%# Bind("Name") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:RequiredFieldValidator ID="rfvHierarchyName" runat="server" SetFocusOnError="True" ControlToValidate="txtHierarchyName" ErrorMessage="Enter Reference." ValidationGroup="grpHierarchy">
<asp:TextBox ID="txtHierarchyName" CssClass="textBoxSmall" Style="visibility: visible" runat="server" Text='<%# Bind("Name") %>' MaxLength="50"></asp:TextBox>
</asp:RequiredFieldValidator>
<span style="color: Red;">*</span>
<asp:RegularExpressionValidator ID="regexValiator3" runat="server" ControlToValidate="txtAPReference" ErrorMessage='Invalid Reference.' Display="None" ValidationGroup="grpHierarchy" ValidationExpression='([^<>\"\^])*'>
</asp:RegularExpressionValidator>
</EditItemTemplate>
<FooterTemplate>
<asp:RequiredFieldValidator ID="rfvHierarchyName" runat="server" SetFocusOnError="True" ControlToValidate="txtHierarchyName" ErrorMessage="Enter Reference." ValidationGroup="grpfHierarchy">
<asp:TextBox ID="txtHierarchyName" CssClass="textBoxSmall" Style="visibility: visible" runat="server" Text='<%# Bind("Name") %>' MaxLength="50"></asp:TextBox>
</asp:RequiredFieldValidator>
<span style="color: Red;">*</span>
<asp:RegularExpressionValidator ID="regexValiator4" Display="None" runat="server" ControlToValidate="txtHierarchyName" ErrorMessage='Invalid Reference.' ValidationGroup="grpfHierarchy" ValidationExpression='([^<>\"\^])*'>
</asp:RegularExpressionValidator>
</FooterTemplate>
<ItemStyle CssClass="textAlignLeft" />
<HeaderStyle CssClass="textAlignLeft" />
<FooterStyle CssClass="textAlignLeft" />
</asp:TemplateField>
<asp:TemplateField HeaderText="LevelName">
<ItemTemplate>
<asp:Label ID="lblName" runat="server" Text='<%# Bind("Level.Name") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:RequiredFieldValidator ID="rfvLevelName" runat="server" SetFocusOnError="True" ControlToValidate="ddlLevelName" ErrorMessage="Select Level Number." Width="100px" CssClass="redborderlarge" ValidationGroup="grpHierarchy" InitialValue="--Select--">
<asp:DropDownList ID="ddlLevelName" Width="200px" Style="visibility: visible" runat="server">
</asp:DropDownList>
</asp:RequiredFieldValidator><span style="color: Red; margin-top: 4px;">*</span>
</EditItemTemplate>
<FooterTemplate>
<asp:RequiredFieldValidator ID="rfvCustomerName" runat="server" SetFocusOnError="True" ControlToValidate="ddlLevelName" ErrorMessage="Select Customer." ValidationGroup="grpfHierarchy" InitialValue="--Select--">
<asp:DropDownList ID="ddlLevelName" Width="200px" Style="visibility: visible" runat="server">
</asp:DropDownList>
</asp:RequiredFieldValidator><span style="color: Red;">*</span>
</FooterTemplate>
<ItemStyle CssClass="textAlignLeft" />
<HeaderStyle CssClass="textAlignLeft" />
</asp:TemplateField>
<asp:TemplateField HeaderText="Action" ShowHeader="False">
<ItemTemplate>
<asp:LinkButton ID="btnHierarchyEdit" runat="server" CausesValidation="false" CommandName="Edit" Text="Edit"></asp:LinkButton>
</ItemTemplate>
<EditItemTemplate>
<asp:LinkButton ID="btnHierarchyUpdate" runat="server" CommandName="Select" Text="Update" CausesValidation="true" ValidationGroup="grpfHierarchy" OnClick="btnHierarchyUpdate_Click" OnClientClick="return ToggleCursor2(1,'grpAP',true);"></asp:LinkButton>
<asp:LinkButton ID="btnHierarchyCancel" runat="server" CausesValidation="false" CommandName="Select" Text="Cancel" OnClick="btnHierarchyCancel_Click"></asp:LinkButton>
</EditItemTemplate>
<FooterTemplate>
<asp:LinkButton ID="btnHierarchyAdd" runat="server" CausesValidation="true" ValidationGroup="grpfHierarchy" CommandName="New" Text="Add" OnClientClick="return true;"></asp:LinkButton>
</FooterTemplate>
<ItemStyle CssClass="textAlignCenter" />
<HeaderStyle CssClass="textAlignCenter" />
<FooterStyle CssClass="textAlignCenter" />
</asp:TemplateField>
</Columns>
<HeaderStyle CssClass="Header" />
<RowStyle CssClass="Row" />
<FooterStyle CssClass="Header borderBttm" />
</asp:GridView>
and my code behind code is this event is not firing.where I am wrong
protected void grdHierarchy_RowEditing(object sender, GridViewEditEventArgs e)
{
grdHierarchy.EditIndex = e.NewEditIndex;
grdHierarchy.ShowFooter = false;
}
protected void grdHierarchy_RowCommand(object sender, GridViewCommandEventArgs e)
{
if (e.CommandName.Equals("New"))
{
Hierarchy Hierarchy = new Hierarchy();
TextBox txtHierarchyName = (TextBox)grdHierarchy.FooterRow.FindControl("txtHierarchyName");
DropDownList ddlLevelName = (DropDownList)grdHierarchy.FooterRow.FindControl("ddlLevelName");
string HierarchyName = txtHierarchyName.Text.Trim();
bool IsNameExist = Hierarchy.IsNameExist(Session, HierarchyName);
if (IsNameExist == false)
{
Hierarchy.Id = 0;
Hierarchy.Name = HierarchyName;
Hierarchy.LevelId = Convert.ToInt64(ddlLevelName.SelectedValue);
Hierarchy.CreatedDtTm = DateTime.Now;
Hierarchy.ModifiedDtTm = DateTime.Now;
Hierarchy.Save(Session);
fillHierarchyGrid();
}
else
{
cGlobalUI.showPopupMsg(Page, "Hierarchy Name is already Exist", cGlobalUI.MessageType.mtInformation);
}
}
}

Gridview edit mode for more that one row

I have a Gridview that allows user to edit and delete the records. I am using .net 3.5 using C#.
When I have just one record my edit command is working fine but problem comes when there are more that 1 record in my gridview.
In this case while binding the controls it it is unable to find the controls the second time and thus throws the error.
Here is my code:
protected void gdScheduleNew_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
if (ViewState["Updating"].Equals(true))
{
TextBox txtactsta = (TextBox)e.Row.FindControl("txtactualstartDate");
TextBox txtactend = (TextBox)e.Row.FindControl("txtactualendDate");
LinkButton lnkUpdate = (LinkButton)e.Row.FindControl("lnkUpdate");
txtactsta.Attributes.Add("ReadOnly", "true");
txtactend.Attributes.Add("ReadOnly", "true");
}
}
}
markup code is:
<asp:GridView ID="gdScheduleNew" runat="server" Width="100%" SelectedIndex="0"
CellPadding="4" AutoGenerateColumns="False" ForeColor="#333333" Height="100px"
OnRowDataBound="gdScheduleNew_RowDataBound" onrowediting="gdSchedule_RowEditing">
<FooterStyle Font-Bold="True" ForeColor="White" />
<RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
<Columns>
<asp:TemplateField HeaderText="Planned Efforts">
<ItemTemplate>
<asp:Label ID="lblscheduleid" runat="server" Text='<%# Bind("scheduleid") %>'
Visible="false"></asp:Label>
<asp:Label ID="lblPlannedEffort" runat="server" Text='<%# Bind("sepcet") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:Label ID="lblscheduleid" runat="server" Text='<%# Bind("scheduleid") %>'
Visible="false"></asp:Label>
<asp:TextBox ID="txtsepcet" runat="server" Text='<%# Bind("sepcet") %>'
Width="88px"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="ftxtsepcet" runat="server" Width="88px"></asp:TextBox>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Actual Efforts">
<ItemTemplate>
<asp:Label ID="lblActualEffort" runat="server"
Text='<%# Bind("actualeffort") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="txtactualeffort" runat="server"
Text='<%# Bind("actualeffort") %>' Width="88px"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="ftxtactualeffort" runat="server" Width="88px"></asp:TextBox>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Planned Start Date">
<ItemTemplate>
<asp:Label ID="lblPlannedStart" runat="server"
Text='<%# Bind("plannedstartDate") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="txtplannedstartDate" runat="server"
Text='<%# Bind("plannedstartDate") %>' class="dateclass" Width="88px"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="ftxtplannedstartDate" runat="server" class="dateclass"
Width="88px"></asp:TextBox>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Planned End Date">
<ItemTemplate>
<asp:Label ID="lblPlannedEnd0" runat="server"
Text='<%# Bind("plannedendDate") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="txtplannedendDate" runat="server"
Text='<%# Bind("plannedendDate") %>' class="dateclass" Width="88px"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="ftxtplannedendDate" runat="server" class="dateclass"
Width="88px"></asp:TextBox>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Actual Start Date">
<ItemTemplate>
<asp:Label ID="lblActualStart" runat="server"
Text='<%# Bind("actualstartDate") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="txtactualstartDate" runat="server"
Text='<%# Bind("actualstartDate") %>' class="dateclass" Width="88px"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="ftxtactualstartDate" runat="server" class="dateclass"
Width="88px"></asp:TextBox>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Actual End Date">
<ItemTemplate>
<asp:Label ID="lblActualEnd" runat="server"
Text='<%# Bind("actualendDate") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="txtactualendDate" runat="server"
Text='<%# Bind("actualendDate") %>' class="dateclass" Width="88px"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="ftxtactualendDate" runat="server" class="dateclass"
Width="88px"></asp:TextBox>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Member Name">
<ItemTemplate>
<asp:Label ID="lblMember" runat="server" Text='<%# Bind("membername") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:DropDownList ID="ddlmem" runat="server" DataTextField="MemberName" DataValueField="MemberID">
</asp:DropDownList>
</EditItemTemplate>
<FooterTemplate>
<asp:DropDownList ID="fddlmem" runat="server" DataTextField="MemberName" DataValueField="MemberID">
</asp:DropDownList>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Status">
<ItemTemplate>
<asp:Label ID="lblStatus" runat="server" Text='<%# Bind("status") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Edit" ShowHeader="False">
<EditItemTemplate>
<asp:LinkButton ID="lnkUpdate" runat="server" CausesValidation="True" CommandName="Update" Text="Update"></asp:LinkButton>
<br />
<asp:LinkButton ID="LnkCancel" runat="server" CausesValidation="False" CommandName="Cancel" Text="Cancel"></asp:LinkButton>
</EditItemTemplate>
<FooterTemplate>
<asp:LinkButton ID="lnkAddnew" runat="server" CausesValidation="true"
CommandName="AddNew" Text="Submit"></asp:LinkButton>
</FooterTemplate>
<ItemTemplate>
<asp:LinkButton ID="lnkEdit" runat="server" CausesValidation="False"
CommandName="Edit" Text="Edit"></asp:LinkButton>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
The error is on this line: txtactsta.Attributes.Add("ReadOnly", "true");:
object reference no set to an instance of object
How can I fix this?

Doesn't gdScheduleNew_RowDataBound get called for every row in your gridview? txtactualstartDate and txtactualendDate only exist on edit rows, they do not exist on non editing rows.
Try this:
if (e.Row.RowType == DataControlRowType.DataRow && e.Row.RowState == DataControlRowState.Edit)

how to keep the textbox values in asp.net gridview after checking the required field validation

I have a regular gridview with insert,edit,update, delete operations as in below image:
Before inserting data to the DB, I am doing the validation on the textboxes if they are filled or empty like this:
if (txtNewID.Text == "")
{
string message = "Please enter ID";
ScriptManager.RegisterClientScriptBlock(Page, this.GetType(), "Alert", "alert('" + message + "')", true);
isValid = false;
}
But after clicking the OK button of the alert message, the values that i added in the required textboxes are getting lost. How to keep the values of the textboxes in gridview?
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="Code, Type" OnRowCancelingEdit="GridView1_RowCancelingEdit" OnRowDataBound="GridView1_RowDataBound" OnRowEditing="GridView1_RowEditing" OnRowUpdating="GridView1_RowUpdating" OnRowCommand="GridView1_RowCommand" ShowFooter="True" OnRowDeleting="GridView1_RowDeleting">
<Columns>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<tr>
<td class="style1" >
<asp:GridView ID="gridID" DataKeyNames="Tracker_ID , Current_Status" runat="server"
GridLines="Both" Width="600px" BorderColor="Black"
ShowFooter="true" AutoGenerateColumns="false"
onrowcancelingedit="gridID_RowCancelingEdit"
onrowediting="gridID_RowEditing" onrowcommand="gridID_RowCommand"
onrowdeleting="gridID_RowDeleting" onrowdatabound="gridID_RowDataBound" onrowupdating="gridID_RowUpdating"
>
<Columns>
<asp:TemplateField HeaderStyle-BackColor="#1B7AE0" HeaderStyle-Font-Size="10" HeaderText="ID#">
<EditItemTemplate>
<asp:TextBox ID="ID" BorderWidth="1" Text='<%# Eval("ID") %>' Width="50px" runat="server"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="txtNewID" BorderWidth="1" Width="50px" runat="server"></asp:TextBox> </FooterTemplate>
<ItemTemplate>
<asp:Label ID="lblID" Font-Size="Smaller" runat="server" Text='<%# Bind("ID") %>'></asp:Label>
</ItemTemplate>
<HeaderStyle BackColor="#1B7AE0" Font-Size="10pt"></HeaderStyle>
</asp:TemplateField>
<asp:TemplateField HeaderText="ID Description" HeaderStyle-BackColor="#1B7AE0" HeaderStyle-Font-Size="10">
<EditItemTemplate>
<asp:TextBox ID="IDDesc" Text='<%# Eval("ID_Description") %>' Width="99px" BorderWidth="1" runat="server"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="txtNewIDDesc" BorderWidth="1" Width="99px" runat="server"></asp:TextBox> </FooterTemplate>
<ItemTemplate>
<asp:Label ID="lblIDDesc" Font-Size="Smaller" Text='<%# Bind("ID_Description") %>' runat="server"></asp:Label>
</ItemTemplate>
<HeaderStyle BackColor="#1B7AE0" Font-Size="10pt"></HeaderStyle>
</asp:TemplateField>
<asp:TemplateField HeaderText="HCL Author" HeaderStyle-BackColor="#1B7AE0" HeaderStyle-Font-Size="10">
<EditItemTemplate>
<asp:TextBox ID="txtHclAuthor" Text='<%# Eval("HCL_Author") %>' Width="95px" BorderWidth="1" runat="server"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="txtNewHclAuthor" BorderWidth="1" Width="95px" runat="server"></asp:TextBox> </FooterTemplate>
<ItemTemplate>
<asp:Label ID="lblHclAuthor" Font-Size="Smaller" Text='<%# Bind("HCL_Author") %>' runat="server"></asp:Label>
</ItemTemplate>
<HeaderStyle BackColor="#1B7AE0" Font-Size="10pt"></HeaderStyle>
</asp:TemplateField>
<asp:TemplateField HeaderText="Xerox Author" HeaderStyle-BackColor="#1B7AE0" HeaderStyle-Font-Size="10">
<EditItemTemplate>
<asp:TextBox ID="txtXeroxAuthor" Text='<%# Eval("Xerox_Author") %>' Width="95px" BorderWidth="1" runat="server"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="txtNewXeroxAuthor" BorderWidth="1" Width="95px" runat="server"></asp:TextBox> </FooterTemplate>
<ItemTemplate>
<asp:Label ID="lblXeroxAuthor" Font-Size="Smaller" Text='<%# Bind("Xerox_Author") %>' runat="server"></asp:Label>
</ItemTemplate>
<HeaderStyle BackColor="#1B7AE0" Font-Size="10pt"></HeaderStyle>
</asp:TemplateField>
<asp:TemplateField HeaderText="Track" HeaderStyle-BackColor="#1B7AE0" HeaderStyle-Font-Size="10">
<EditItemTemplate>
<asp:TextBox ID="IDTrack" Text='<%# Eval("Track") %>' Width="80px" BorderWidth="1" runat="server"></asp:TextBox>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="txtNewIDTrack" BorderWidth="1" Width="80px" runat="server"></asp:TextBox> </FooterTemplate>
<ItemTemplate>
<asp:Label ID="lblIDTrack" Font-Size="Smaller" Text='<%# Bind("Track") %>' runat="server"></asp:Label>
</ItemTemplate>
<HeaderStyle BackColor="#1B7AE0" Font-Size="10pt"></HeaderStyle>
</asp:TemplateField>
</Columns>
</asp:GridView>
</td> </tr> </ContentTemplate>
</asp:UpdatePanel>

Whenever PostBack event is called then we can loss the page data.Did you place the grid in updatepanel otherwise place it in grid if you didn't get maintain the values in viewstate.

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.requiredfieldvalidator.aspx
Bind the validator to the textbox you need to be required before a submit/post is valid using the ControlToValidate property.

Try to find required field validator dynamically on RowDataBoundEvent of Grid View.
TextBox tb=e.Row.FindControl("txtBox") as TextBox;
tb.ValidationGroup=e.RowIndex;
RequiredFieldvalidation rv=e.Row.FindControl("rv") as
RequiredFieldValidator; rv.ControlTovalidate=tb; rv.ErrorMessage;
rv.ErrorMessage="*";
rv.ValidationGroup=e.RowIndex;