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How to delete a row from a dataTable and adjust a cost

Posted on 2009-04-08
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Last Modified: 2013-11-26
Hello,
 I am working on a basic shopping cart that will allow users to register for an event. I have built the cart using a dataTable and I have been able to add the users as well as calculate a running total. I am having difficulty though figuring out how to delete a row from the shopping cart. If a user decides they want to remove an attendee I want them to be able to click on a remove link in my datagrid and remove the user. This function should remove the row as well as adjust the total cost.
I have built a similar page in vb.net but I am having trouble translating the code over to C#.net  When I try to call the dataTable from another function I get an error that the dataTable name does not exist in the current context.

Can you please help me understand what I am missing and how to correct this so that I am able to remove items from my shopping cart.
Thanks in advance,
//create shopping cart
    private void DataTable()
    {
        DataTable MyDT = new DataTable();
        DataRow MyRow;
 
        if (ViewState["DataTable"] == null)
        {
            MyDT.Columns.Add("regID", System.Type.GetType("System.Int32"));
            MyDT.Columns.Add("Fname");
            MyDT.Columns.Add("Lname");
            MyDT.Columns.Add("Title");
            MyDT.Columns.Add("Agency");
            MyDT.Columns.Add("Email");
            MyDT.Columns.Add("Shirt");
            MyDT.Columns.Add("FstAtt");
            MyDT.Columns.Add("Price", typeof(Decimal));
            MyRow = MyDT.NewRow();
            MyRow[0] = MyDT.Rows.Count + 1;
            MyRow[1] = TxtFName.Text;
            MyRow[2] = TxtLName.Text;
            MyRow[3] = TxtTitle.Text;
            MyRow[4] = TxtAgency.Text;
            MyRow[5] = TxtEmail.Text;
            MyRow[6] = ddShirt.SelectedItem.Text;
            MyRow[7] = ddAttend.SelectedItem.Text;
            MyRow[8] = 100; //current rate for User Conference registration
            MyDT.Rows.Add(MyRow);
            //clear fields
            TxtFName.Text = "";
            TxtLName.Text = "";
            TxtTitle.Text = "";
            TxtAgency.Text = "";
            TxtEmail.Text = "";
            ddShirt.SelectedIndex = -1;
            ddAttend.SelectedIndex = -1;
            //Calculate Total for Shopping Cart
            Decimal Total = 0.00M;
            foreach (DataRow Row in MyDT.Rows)
            {
                Total += (Decimal)Row["Price"];
            }
            runTotalLBL.Text = Total.ToString();
        }
        else
        {
            MyDT = (DataTable)ViewState["DataTable"];
            MyRow = MyDT.NewRow();
            MyRow[0] = MyDT.Rows.Count + 1;
            MyRow[1] = TxtFName.Text;
            MyRow[2] = TxtLName.Text;
            MyRow[3] = TxtTitle.Text;
            MyRow[4] = TxtAgency.Text;
            MyRow[5] = TxtEmail.Text;
            MyRow[6] = ddShirt.SelectedItem.Text;
            MyRow[7] = ddAttend.SelectedItem.Text;
            MyRow[8] = 100;
            MyDT.Rows.Add(MyRow);
            //clear fields after each registrant is entered
            TxtFName.Text = "";
            TxtLName.Text = "";
            TxtTitle.Text = "";
            TxtAgency.Text = "";
            TxtEmail.Text = "";
            ddShirt.SelectedIndex = -1;
            ddAttend.SelectedIndex = -1;
            //Calculate Total for Shopping Cart
            Decimal Total = 0.0M;
            foreach (DataRow Row in MyDT.Rows)
            {
                Total += (Decimal)Row["Price"];
            }
            runTotalLBL.Text = Total.ToString();
        }
        ViewState["DataTable"] = MyDT;
        //bind datatable to datagrid
        dg.DataSource = MyDT;
        dg.DataBind();
    }
 
    //add attendees to roster datagrid
    protected void AddToCart(object sender, EventArgs e)
    {
        DataTable();
    }
 
    //remove attendee from data grid
    protected void Delete_Item(object source, DataGridCommandEventArgs e)
    {
       //Here is where I get stuck. In vb.net the datatable was recognized across functions however here it only seems to be accessible within the function "DataTable"
        ViewState["DataTable"] = MyDT;
 
 
 
    }

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Question by:rlcrews
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2 Comments
 
LVL 14

Accepted Solution

by:
jjardine earned 750 total points
ID: 24102279
It i sbecause MyDT is only declared in the function DataTable.    YOu don't have it declared in Delete_Item.   You would have to declare it outside of the DataTable function or declare it again in Delete_Item.  It looks like you are doing this backwards though.   Wouldn't you want to set MyDT = the Veiwstate version of the datatable to work with it?
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LVL 83

Assisted Solution

by:CodeCruiser
CodeCruiser earned 750 total points
ID: 24105865
//Here is where I get stuck. In vb.net the datatable was recognized across functions however here it only seems to be accessible within the function "DataTable"

This statement is not valid. Even in VB, you could not access the variable outside of the function in which you declare it.

Try this code. I hope you could convert it into C#


Dim MyDT as DataTable = ViewState["DataTable"] = MyDT
if not isnothing(myDT) then
   myDT.DefaultView.RowFilter = "ItemID = " & ItemID 
   if MyDT.DefaultView.Count = 1 Then
      TotalAmount = TotalAmount - myDT.DefaultView.Item(0).Item("Amount")
      myDT.DefaultView.Item(0).Delete
   End if
   MyDT.DefaultView.Rowfilter = ""
end if

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