Deleting row from Arraylist

Question

Does anybody have any help,i am using an Arraylist to store details in a Session. When items are added to shopping cart i want to be able to have some functionality, i am beginning with a Delete button (eventually i would like an Edit button too) so i have tried two ways for the Delete button with neither working for me, first atttempt:

sc.aspx page

    <asp:TemplateField> 
    <ItemTemplate> 
        <asp:Button ID="btnDelete" runat="server" CommandArgument='<%# ((GridViewRow)Container).RowIndex %>' CommandName="deleterow" Text="Delete" /> 
    </ItemTemplate>
</asp:TemplateField>'

With:

'onrowcommand="DeleteRowBtn_Click"'

sc.aspx.cs

'protected void DeleteRowBtn_Click(object sender, GridViewCommandEventArgs e)
{
    int rowIndex = Convert.ToInt32(e.CommandArgument); 
}'

second attempt:

sc.aspx

'OnRowDeleting="GridView1_RowDeleting"'

 '<asp:CommandField ShowDeleteButton="True" />'

sc.aspx.cs

'protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
    ArrayList remove = (ArrayList)Session["aList"];
    DataRow dr = remove.Rows[e.RowIndex];
    remove.Rows.Remove(dr);
    GridView1.EditIndex = -1;
    FillShopCart();
}'

Please edit your question: 1. Add the binding code (FillShopCart?). 2. ArrayList don't have the Rows property. 3. Don't use ArrayList but List<T>. — Amiram Korach
– Amiram Korach, Commented Jul 11, 2012 at 14:07
Why ArrayList instead of List<T>? Are you using .net 1.x? — CodesInChaos
– CodesInChaos, Commented Jul 11, 2012 at 14:11
I was only taught Arraylist and never shown List<T>, this is my first ever 'project' using asp so i will have to try find some tutorials on List<T>.For this 'project' i need to use 2.0 My FillShopCart is as follows: private void FillShopCart() { ArrayList aList; aList = (ArrayList)Session["aList"]; GridView1.DataSource = aList; GridView1.DataBind(); } — Gavin Gaughran
– Gavin Gaughran, Commented Jul 11, 2012 at 20:25

Tim Schmelter · Accepted Answer · 2012-07-11 14:22:19Z

1

This doesn't work because an ArrayList has no Rows property but an indexer like arrays:

ArrayList remove = (ArrayList)Session["aList"];
DataRow dr = remove.Rows[e.RowIndex];

So this could work

DataRow dr = (DataRow)remove[e.RowIndex];

Sidenote: you should avoid ArrayList (or HashTable) if you're using at least .NET 2.0 and use the strong typed collections like List<T> or Dictionary<TKey, TValue> instead.

edited Jul 11, 2012 at 14:22

answered Jul 11, 2012 at 14:11

Tim Schmelter

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3 Comments

Gavin Gaughran Over a year ago

Hi Tim, thank you for the response. but I still couldnt get this to work, i put in the line and even tried different ways and no joy, i now have ArrayList remove = (ArrayList)Session["aList"]; DataRow dr = (DataRow)remove[e.RowIndex]; remove.Remove(dr); Session["aList"] = remove; GridView1.EditIndex = -1; FillShopCart(); But i get "unable to cast object type of "CustomerOrder" to type of "System.Data.Datarow". CustomerOrder is my class where i retrieve the details for to be displayed

Tim Schmelter Over a year ago

Then you need to cast it to CustomerOrder instead of DataRow. I don't know what this class has or can, but apparenetly it's the datasource of your GridView.

Gavin Gaughran Over a year ago

Thanks Tim, ended up with: ArrayList remove = (ArrayList)Session["aList"]; CustomerOrder order = (CustomerOrder)remove[e.RowIndex]; remove.Remove(order); Session["aList"] = remove; FillShopCart(); Thanks for your time...

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