Loading, Updating and displaying Generic List Class

Question

Goal in mind, the concept is kind of like a shopping cart, so as they add items to list(Detail) it keeps the items they are adding in memory. This works when ever I first load the list(grid) and add more rows. But if I set the first row and set the item and price and then decide to add 3 more rows then the info I had added gets deleted instead of keeping its values and just load more lines to the list which would repopulate the gridview. In the past I have done this with datatables but I want to be able to move from that and use this List Class Also I have it set as viewstate so I can use it through out my page.

private ListArDocumentdetail Detail
{
    get
    {
        ListArDocumentdetail _detail = new ListArDocumentdetail();
        if (ViewState["Detail"] != null)
        {
            _detail = (ListArDocumentdetail)ViewState["Detail"];    
        }
        return _detail;
     }
     set
     {
        ViewState["Detail"] = value;
     }
}
protected void Page_Load(object sender, EventArgs e)
{
    //creates 2 rows to start off
    CreateRows(2);
}
public void CreateRows(int rowstoadd)
{
    int newtotalrows = Detail.Count + rowstoadd - 1;
    for (int i = Detail.Count; i <= newtotalrows; i++)
    {
        ArDocumentdetail detail = new ArDocumentdetail();
        detail.Lineid = i;
        detail.Itemid = 0;
        detail.Quantity = 1;
        if (Detail.Count > 0)
            Detail.Insert(Detail.Count, detail);
        else
            Detail.Add(detail);

        Detail = Detail;
    }
    gvInvoiceDetail.DataSource = Detail;
    gvInvoiceDetail.DataBind();

    GridViewRow row = gvInvoiceDetail.Rows[gvInvoiceDetail.Rows.Count - 1];
    ImageButton btnAdd = (ImageButton)row.FindControl("btnAdd");
    btnAdd.Visible = true;
}
protected void ibAdd_Click(object sender, ImageClickEventArgs e)
{
    //user can type in how many rows they want to add on to current amount of rows
    //so since grid starts off at 2 and they type 3 the grid refreshes with 5 rows.
    CreateRows(Convert.ToInt32(txtRows.Text));
}

protected void UpdateRow(object sender, EventArgs e)
{
    ImageButton btnUpdate = sender as ImageButton;
    GridViewRow row = btnUpdate.NamingContainer as GridViewRow;

    TextBox txtPrice = (TextBox)row.FindControl("txtPrice");
    TextBox txtQuantity = (TextBox)row.FindControl("txtQuantity");
    DropDownList ddlDescription = (DropDownList)row.FindControl("ddlDescription");

    int index = Detail.FindIndex(f => f.Lineid == row.RowIndex);
    Detail[index].Itemid = Convert.ToInt32(ddlDescription.SelectedValue);
    Detail[index].Price = Convert.ToDecimal(txtPrice.Text);
    Detail[index].Subtotal = Convert.ToDecimal(Detail[index].Price * Convert.ToInt32(txtQuantity.Text));

}

user240141 · Accepted Answer · 2011-12-07 18:20:30Z

1

I can suggest you the logic:

Push a list into viewstate say Viewstate["List"],
Let a user chose an item. Then List list = (List)Viewstate["List"];
Add the selected item to List list. i.e. list.Add(item);
Now push the item back to viewstate. Viewstate["list"] = list;
Bind it to grid or display it on page. Whatever you want.

answered Dec 7, 2011 at 18:20

user240141

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3 Comments

Andres Over a year ago

beautiful man thanks! another note was that in my gridview rowdatabound I wasn't setting the values from the list in viewstate...that's my bad..

user240141 Over a year ago

Sorry , I did'nt get you. Could you elaborate your situation.

Andres Over a year ago

Your logic help me add/update correctly but what I was doing wrong was when databinding my grid I was setting the values of the controls correctly..like my dropdownlist for items i wasn't grabbing the value stored in the list so it was always showing blank..thanks

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