如何从gridview中获取单元格值

Question

protected void CovidSelfDecleartionDeatils_RowCommand(object sender, GridViewCommandEventArgs e)
{
try
{
ShowallRecord();
if (e.CommandArgument != "")
{
int Index = Convert.ToInt32(e.CommandArgument);
if (e.CommandName=="Select")
{
DataTable dt_main = new DataTable();
dt_main = (DataTable)ViewState["ReportData"];

GridViewRow clickedRow = CovidSelfDecleartionDeatils.Rows[Index];
Session["Filepath"] = clickedRow.Cells[9].Text;
//Session["Filepath"] = CovidSelfDecleartionDeatils.Rows[Index].FindControl("FilePath");
Session["Filepath1"] = CovidSelfDecleartionDeatils.DataKeys[Index]["Filepath"].ToString();
string filepath = Session["Filepath"].ToString();
//DataGridViewSelectedRowCollection rows = dataGridView1.SelectedRows;
//string val = (string)rows[2].Cells["Late_Time"].Value;
}
}
}
catch
{
}
}

<asp:GridView ID="CovidSelfDecleartionDeatils" runat="server" DataKeyNames="EmployeeCode" AutoGenerateColumns="False" 
BackColor="#333333" CellPadding="5" CellSpacing="3" ForeColor="Black"  Width="100%" Height="300px"  OnRowCommand="CovidSelfDecleartionDeatils_RowCommand" >
<Columns>


<%--   <asp:BoundField DataField="InitiateMPPId" HeaderText="InitiateMPPId" >
<HeaderStyle HorizontalAlign="Center" />
</asp:BoundField>--%>
<asp:BoundField DataField="EmployeeCode" HeaderText="EmployeeCode" ItemStyle-HorizontalAlign="Left" Visible="false"
HeaderStyle-HorizontalAlign="Left" ControlStyle-BorderStyle="None" ItemStyle-CssClass="per10" 
HeaderStyle-CssClass="header-center">
</asp:BoundField>
<%-- <asp:BoundField DataField="EmployeeCode" HeaderText="EmployeeCode" ItemStyle-HorizontalAlign="Left" Visible="false"
HeaderStyle-HorizontalAlign="Left" ControlStyle-BorderStyle="None" ItemStyle-CssClass="per10" 
HeaderStyle-CssClass="header-center">
</asp:BoundField>--%>
<asp:BoundField DataField="EmpName" HeaderText="Employee"  ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" >

</asp:BoundField>
<asp:BoundField DataField="Decleartion_Date" HeaderText="Date Decleartion"  ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" DataFormatString="{0:dd-MM-yyyy}" >

</asp:BoundField>
<asp:BoundField DataField="Ferver" HeaderText="Ferver"   ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" />
<asp:BoundField DataField="Cough" HeaderText="Cough"   ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left"/>
<asp:BoundField DataField="Breathlessness" HeaderText="Breathlessness"  ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left"/>


<asp:BoundField DataField="OtherDiseases" HeaderText="OtherDiseases" ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" ItemStyle-CssClass="per50" ItemStyle-Height="25" HeaderStyle-Height="25" HeaderStyle-CssClass="header-center" HeaderStyle-Wrap="true"/>
<asp:BoundField DataField="FileName" HeaderText="FileName" ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" ItemStyle-CssClass="per50" ItemStyle-Height="25" HeaderStyle-Height="25" HeaderStyle-CssClass="header-center" HeaderStyle-Wrap="true" Visible="false" />
<asp:BoundField DataField="DeclarationID" HeaderText="DeclarationID" ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" ItemStyle-CssClass="per50" ItemStyle-Height="25" HeaderStyle-Height="25" HeaderStyle-CssClass="header-center" HeaderStyle-Wrap="true" Visible="false" />
<asp:BoundField DataField="FilePath" HeaderText="FilePathfordownload" ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" ItemStyle-CssClass="per50" ItemStyle-Height="25" HeaderStyle-Height="25" HeaderStyle-CssClass="header-center" HeaderStyle-Wrap="true" Visible="false" />
<asp:BoundField DataField="ContactwithCovid" HeaderText="Incontact with covid patient Last(14) days" ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" ItemStyle-CssClass="per50" ItemStyle-Height="25" HeaderStyle-Height="25" HeaderStyle-Width="15%" HeaderStyle-CssClass="header-center" HeaderStyle-Wrap="true"/>

<%--<asp:TemplateField HeaderText="Status" ItemStyle-HorizontalAlign="Center">
<ItemTemplate>
<asp:ImageButton ID="btn_delete_record"
Width="20px" Height="20px" runat="server" ImageUrl="~/Content/Images/NewIcons/PDF.png" />
</ItemTemplate>
</asp:TemplateField>--%>
<asp:ButtonField CommandName="Select" ControlStyle-CssClass="button" ButtonType="Image" ImageUrl="~/Content/Images/NewIcons/PDF.png"
ItemStyle-Width="5px" HeaderText="Download Attachment" />

<asp:BoundField DataField="City" HeaderText="City"  ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" />
<asp:BoundField DataField="TravelDate" HeaderText="TravelDate"  ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" DataFormatString="{0:dd-MM-yyyy}" />
<asp:BoundField DataField="StateName" HeaderText="StateName"  ItemStyle-HorizontalAlign="Left" HeaderStyle-HorizontalAlign="Left" />

</Columns>
<FooterStyle BackColor="#CCCCCC" />
<HeaderStyle BackColor="#5e5d5d" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="#CCCCCC" ForeColor="Black" HorizontalAlign="Left" />
<RowStyle BackColor="White" />
<SelectedRowStyle BackColor="#000099" Font-Bold="True" ForeColor="White" />
<SortedAscendingCellStyle BackColor="#F1F1F1" />
<SortedAscendingHeaderStyle BackColor="Gray" />
<SortedDescendingCellStyle BackColor="#CAC9C9" />
<SortedDescendingHeaderStyle BackColor="#383838" />
</asp:GridView>

我表现出色有什么错；对象引用未设置"；当我在会话中保存值时

Answer 1

删除visible=false并定义新的css类，如

.donotshow { display: none; }

并将其添加到HeaderStyle-CssClass和ItemStyle-CssClass