problem return RadioList value to control in GridView

Hello

I designed a form to add sub-category depends on user select from Main categroy (dropdownlist)

A gridview designed depends on that video GRIDVIEW (CRUD):

https://www.youtube.com/watch?v=pH7E-GM8HjE

when I insert item a fiest error is:

I anlyising the suppoose error maybe from Id field because maybe be empty.

I designe a new column in gridview to pass value from dropdownlist depends on (Autopostpack) property like these:

Literal txtid = (Literal)gvsubcat.FooterRow.FindControl("TBF_footer");
txtid = RadioButtonList1.SelectedItem.Text;

the error is cannot implicity convert type string to system.web.UI.webcontrol.Literal

so there is a new way to solve that mistake. Iam searched long time to solve it, but nothing

here a source code:

<asp:GridView ID="gvsubcat" runat="server" AutoGenerateColumns="False" BackColor="White" BorderColor="#CCCCCC" BorderStyle="None" BorderWidth="1px" CellPadding="3" DataKeyNames="Id" DataSourceID="SDS_Subcategory" ShowFooter="True" OnRowCancelingEdit="gvsubcat_RowCancelingEdit" OnRowCommand="gvsubcat_RowCommand" OnRowDeleting="gvsubcat_RowDeleting" OnRowEditing="gvsubcat_RowEditing" OnRowUpdating="gvsubcat_RowUpdating">
<FooterStyle BackColor="White" ForeColor="#000066" />
<HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />
<RowStyle ForeColor="#000066" />
<SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
<SortedAscendingCellStyle BackColor="#F1F1F1" />
<SortedAscendingHeaderStyle BackColor="#007DBB" />
<SortedDescendingCellStyle BackColor="#CAC9C9" />
<SortedDescendingHeaderStyle BackColor="#00547E" />
<Columns>
<asp:BoundField DataField="C_Id" HeaderText="C_Id" SortExpression="C_Id"/>--%>
<asp:TemplateField HeaderText="Id">
<ItemTemplate>
<asp:Label ID="lb_Id" Text='<%#Eval("C_Id") %>' runat="server">asp:Label>
ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="lbE_Id" runat="server" Text='<%#Eval("C_Id") %>'>asp:TextBox>
EditItemTemplate>
<FooterTemplate>
<asp:Literal ID="TBF_footer" runat="server">asp:Literal>
FooterTemplate>
asp:TemplateField>
<asp:TemplateField HeaderText="Name">
<ItemTemplate>
<asp:Label ID="lb_Na" Text='<%#Eval("Su_Name") %>' runat="server">asp:Label>
ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="Name_Edit" runat="server" Text='<%#Eval("Su_Name") %>'>asp:TextBox>
EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="Name_footer" runat="server">asp:TextBox>
FooterTemplate>
asp:TemplateField>
<asp:TemplateField HeaderText="Ingredints">
<ItemTemplate>
<asp:Label ID="Lb_Ing" Text='<%#Eval("Ingredients") %>' runat="server">asp:Label>
ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="Ing_Edit" runat="server" Text='<%#Eval("Ingredients") %>'>asp:TextBox>
EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="Ing_footer" runat="server">asp:TextBox>
FooterTemplate>
asp:TemplateField>
<asp:TemplateField HeaderText="price">
<ItemTemplate>
<asp:Label ID="Lb_pr" Text='<%#Eval("Price") %>' runat="server">asp:Label>
ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="Pri_Edit" runat="server" Text='<%#Eval("Price") %>'>asp:TextBox>
EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="Pri_footer" runat="server">asp:TextBox>
FooterTemplate>
asp:TemplateField>
<asp:TemplateField HeaderText="Image">
<ItemTemplate>
<asp:Image ID="Img_item" runat="server" Height="80px" Width="80px" ImageUrl='<%#Eval("Image") %>' />
ItemTemplate>
<EditItemTemplate>
<asp:FileUpload ID="FU_Edit" runat="server" Visible="false"/>
EditItemTemplate>
<FooterTemplate>
<asp:FileUpload ID="FU_footer" runat="server" />
FooterTemplate>
asp:TemplateField>
<asp:TemplateField HeaderText="Enable">
<ItemTemplate>
<asp:CheckBox ID="Ch_SUcat" runat="server" Enabled='<%#Eval("Visible") %>' />
ItemTemplate>
<EditItemTemplate>
<asp:CheckBox ID="Ch_SUcat_E" runat="server" Enabled='<%#Eval("Visible") %>' />
EditItemTemplate>
<FooterTemplate>
<asp:CheckBox ID="Ch_SUcat_Footer" runat="server" />
FooterTemplate>
asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:ImageButton ID="imgb1" runat="server" ImageUrl="~/images/png/pencil.png" CommandName="Edit" Width="20px" Height="20px" />
<asp:ImageButton ID="imgb2" runat="server" ImageUrl="~/images/png/delete.png" CommandName="Delete" Width="20px" Height="20px" />
ItemTemplate>
<EditItemTemplate>
<asp:ImageButton ID="imgb3" runat="server" ImageUrl="~/images/png/saveblue.png" CommandName="Update" Width="20px" Height="20px" />
<asp:ImageButton ID="imgb4" runat="server" ImageUrl="~/images/png/cancel.png" CommandName="Cancel" Width="20px" Height="20px" />
EditItemTemplate>
<FooterTemplate>
<asp:ImageButton ID="imgb5" runat="server" ImageUrl="~/images/png/addblue.png" CommandName="AddNew" Width="20px" Height="20px" />
FooterTemplate>
asp:TemplateField>
Columns>
asp:GridView>
<asp:ValidationSummary ID="VSummry" runat="server" ForeColor="Red" />
<asp:SqlDataSource ID="SDS_Subcategory" runat="server" ConflictDetection="CompareAllValues" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" DeleteCommand="DELETE FROM Sub_categories WHERE (C_Id = @C_Id)" InsertCommand="INSERT INTO [Sub_categories] ([Su_Name], [Ingredients], [Price], [Image], [Visible], [C_Id]) VALUES (@Su_Name, @Ingredients, @Price, @Image, @Visible, @C_Id)" OldValuesParameterFormatString="original_{0}" SelectCommand="SELECT [Id], [Su_Name], [Ingredients], [Price], [Image], [Visible], [C_Id] FROM [Sub_categories] WHERE ([C_Id] = @C_Id)" UpdateCommand="UPDATE Sub_categories SET Su_Name = @Su_Name, Ingredients = @Ingredients, Price = @Price, Image = @Image, Visible = @Visible FROM Sub_categories INNER JOIN Categories ON Sub_categories.C_Id = Categories.C_Id WHERE (Sub_categories.C_Id = @C_Id)">
<DeleteParameters>
<asp:Parameter Name="C_Id" />
DeleteParameters>
<InsertParameters>
<asp:Parameter Name="Su_Name" Type="String" />
<asp:Parameter Name="Ingredients" Type="String" />
<asp:Parameter Name="Price" Type="Decimal" />
<asp:Parameter Name="Image" Type="String" />
<asp:Parameter Name="Visible" Type="Boolean" />
<asp:Parameter Name="C_Id" Type="Int32" />
InsertParameters>
<SelectParameters>
<asp:ControlParameter ControlID="RadioButtonList1" Name="C_Id" PropertyName="SelectedValue" Type="Int32" />
SelectParameters>
<UpdateParameters>
<asp:Parameter Name="Su_Name" Type="String" />
<asp:Parameter Name="Ingredients" Type="String" />
<asp:Parameter Name="Price" Type="Decimal" />
<asp:Parameter Name="Image" Type="String" />
<asp:Parameter Name="Visible" Type="Boolean" />
<asp:Parameter Name="C_Id" Type="Int32" />
UpdateParameters>
asp:SqlDataSource>
<br />
<asp:Label ID="lblsuccessmessage" Text="" runat="server" ForeColor="Green">asp:Label><br />
<asp:Label ID="lblerrormessage" Text="" runat="server" ForeColor="Red">asp:Label>

Code Behind:

public partial class sub_category : System.Web.UI.Page
{
string connectionString = @"Data Source=(local)\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DbCh.mdf;Integrated Security=True";
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
gvsubcat.DataBind();
}
}
protected void gvsubcat_RowCommand(object sender, GridViewCommandEventArgs e)
{
try
{
if (e.CommandName.Equals("AddNew"))
{
using (SqlConnection sqlcon = new SqlConnection(connectionString))
{
FileUpload fu = (FileUpload)gvsubcat.FooterRow.FindControl("FU_footer");
if (fu.HasFile)
{
string fileName = fu.FileName;
string exten = Path.GetExtension(fileName);
//here we have to restrict file type
exten = exten.ToLower();
string[] acceptedFileTypes = new string[4];
acceptedFileTypes[0] = ".jpg";
acceptedFileTypes[1] = ".jpeg";
acceptedFileTypes[2] = ".gif";
acceptedFileTypes[3] = ".png";
bool acceptFile = false;
for (int i = 0; i <= 3; i++)
{
if (exten == acceptedFileTypes[i])
{
acceptFile = true;
}
}
if (!acceptFile)
{
lblerrormessage.Text = "The file you are trying to upload is not a permitted file type!";
}
else
{
//upload the file onto the server
fu.SaveAs(Server.MapPath("~/images/categories/" + fileName));
//Open Connection with D.B
sqlcon.Open();
string query = "INSERT INTO Sub_categories(Su_Name,Ingredients,Price,Image,Visible,C_Id) VALUES(@Su_Name,@Ingredients,@Price,@Image,@Visible,@C_Id)";
SqlCommand sqlcmd = new SqlCommand(query, sqlcon);
sqlcmd.Parameters.AddWithValue("@C_Id", (gvsubcat.FooterRow.FindControl("TBF_footer") as TextBox).Text.Trim());
sqlcmd.Parameters.AddWithValue("@Su_Name", (gvsubcat.FooterRow.FindControl("Name_footer") as TextBox).Text.Trim());
sqlcmd.Parameters.AddWithValue("@Ingredients", (gvsubcat.FooterRow.FindControl("Ing_footer") as TextBox).Text.Trim());
sqlcmd.Parameters.AddWithValue("@Price", (gvsubcat.FooterRow.FindControl("Pri_footer") as TextBox).Text.Trim());
sqlcmd.Parameters.AddWithValue("@Image", fileName);
//sqlcmd.Parameters.AddWithValue("@Visible", Convert.ToBoolean((gvsubcat.FooterRow.FindControl("Ch_SUcat_Footer") as CheckBox)));
sqlcmd.Parameters.AddWithValue("@Visible", (gvsubcat.FooterRow.FindControl("Ch_SUcat_Footer.text") as CheckBox));
sqlcmd.ExecuteNonQuery();
gvsubcat.DataBind();
lblsuccessmessage.Text = "New Record Added";
lblerrormessage.Text = "";
}
}
}
}
}
catch (Exception ex)
{
lblsuccessmessage.Text = "";
lblerrormessage.Text = ex.Message;
}
}
protected void gvsubcat_RowEditing(object sender, GridViewEditEventArgs e)
{
gvsubcat.EditIndex = e.NewEditIndex;
gvsubcat.DataBind();
}
protected void gvsubcat_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
gvsubcat.EditIndex = -1;
gvsubcat.DataBind();
}
protected void gvsubcat_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
try
{
using (SqlConnection sqlcon = new SqlConnection(connectionString))
{
sqlcon.Open();
string query = "DELETE FROM Categories where Sub_categories.Id =@Id";
SqlCommand sqlcmd = new SqlCommand(query, sqlcon);
sqlcmd.Parameters.AddWithValue("@Id", Convert.ToInt32(gvsubcat.DataKeys[e.RowIndex].Value.ToString()));
sqlcmd.ExecuteNonQuery();
gvsubcat.DataBind();
lblsuccessmessage.Text = "Selected Record has been Deleted.";
lblerrormessage.Text = "";
}
}
catch (Exception ex)
{
lblsuccessmessage.Text = "";
lblerrormessage.Text = ex.Message;
}
}
protected void gvsubcat_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
try
{
using (SqlConnection sqlcon = new SqlConnection(connectionString))
{
sqlcon.Open();
string query = "UPDATE Sub_categories SET Su_Name=@Su_Name, Ingredients=@Ingredients, Price=@Price, Image=@Image, Visible=@Visible where Sub_categories.Id=@Id";
SqlCommand sqlcmd = new SqlCommand(query, sqlcon);
sqlcmd.Parameters.AddWithValue("@Su_Name", (gvsubcat.FooterRow.FindControl("Name_Edit") as TextBox));
sqlcmd.Parameters.AddWithValue("@Ingredients", (gvsubcat.FooterRow.FindControl("Ing_Edit") as TextBox));
sqlcmd.Parameters.AddWithValue("@Price", (gvsubcat.FooterRow.FindControl("Pri_Edit") as TextBox));
sqlcmd.Parameters.AddWithValue("@Image", (gvsubcat.FooterRow.FindControl("FU_Edit")as FileUpload));
sqlcmd.Parameters.AddWithValue("@Visible", Convert.ToBoolean((gvsubcat.FooterRow.FindControl("Ch_SUcat_E") as CheckBox).Checked));
FileUpload fu = (FileUpload)gvsubcat.FindControl("FU_Edit");
if (fu.HasFile)
{
string file = System.IO.Path.Combine(Server.MapPath("~/images/categories/"), fu.FileName);
fu.SaveAs(file);
}
sqlcmd.Parameters.AddWithValue("@Id", Convert.ToInt32(gvsubcat.DataKeys[e.RowIndex].Value.ToString()));
sqlcmd.ExecuteNonQuery();
gvsubcat.EditIndex = -1;
gvsubcat.DataBind();
lblsuccessmessage.Text = "Selected Record has been Updated.";
lblerrormessage.Text = "";
}
}
catch (Exception ex)
{
lblsuccessmessage.Text = "";
lblerrormessage.Text = ex.Message;
}
}
protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
{
Literal txtid = (Literal)gvsubcat.FooterRow.FindControl("TBF_footer");
txtid = RadioButtonList1.SelectedItem.Text;
}
}

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

Rajanikant Hawaldar7y ago
Accepted answer
Hi Aktham, You should debug to identity the which object is null, your accessing property or methods or anyother thing from object but it is null means memory not allocated for the object. go through below to understand
https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it
Thanks, accept the answer if it is correct.
+1
Aktham Mahmoud7y ago
Good times.
Did you know am passed 13 days in trying to solve this problem, and no way..
I know a null value is a problem .
and am trying to put initial value in label at pageload put no way..
and am trying to pass value bu Autopostback but noway
protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
{
    string ddl1 = this.RadioButtonList1.SelectedItem.Value;
    Label lbid = (Label)gvsubcat.FooterRow.FindControl("TBF_footer");
    lbid.Text = ddl1;
}
and the error as you said nulleceptionvaut at line
Label lbid = (Label)gvsubcat.FooterRow.FindControl("TBF_footer");
SO I can't understand if I able to access to control in gridview but I can't pass value
am trying your link
'thanks
0