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c#asp.netgridviewforeachinvalidoperationexception
Albin Åberg
Albin Åberg

Reputation: 39

ASP.net GridView InvalidOperationException on foreach when deleting

I'm using ASP.net and i've added a delete button on a gridview and im trying to remove the row of the button clicked. The thing is though, that i get an InvalidOperationException on my foreach.

I may have other errors in the code or my logic may be wrong so if you see any of it please point them out. Thanks.

gridView cart.ASPX:

<asp:GridView ID="CartGrid" runat="server" AutoGenerateColumns="false" OnRowDeleting="RemoveSelected">
    <Columns>
        <asp:BoundField DataField="product_name" HeaderText="Name" />
        <asp:BoundField DataField="price_per_unit" HeaderText="Price" />
        <asp:BoundField DataField="unit" HeaderText="Unit" />

        <asp:TemplateField>
        <ItemTemplate>
        <asp:LinkButton ID="delSelected" runat="server" Text="Delete" CommandName="Delete"></asp:LinkButton>

        </ItemTemplate>
        <ItemStyle Width="100px" />

        </asp:TemplateField>
    </Columns>
</asp:GridView>

delete method cart.ASPX.CS

protected void RemoveBtn(object sender, GridViewDeleteEventArgs e)
    {
        ArrayList cartList = (ArrayList)Session["cartList"];

        GridViewRow row = (GridViewRow)CartGrid.Rows[e.RowIndex];

        String name = row.Cells[0].Text;
        //String name = (string)CartGrid.DataKeys[e.RowIndex].Value;
        //String name = CartGrid.SelectedRow.Cells[1].Text;

        foreach (product p in cartList)
        {
            if (p.product_name.Equals(name))
            {
                cartList.Remove(p);
            }
        }

        CartGrid.DataBind();
    }

Upvotes: 0

Views: 164

Answers (2)

Anurag_Soni
Anurag_Soni

Reputation: 542

Hi I think the issue is that you are using the cartlist for loop and at the same time you want to delete values from the same which is not possible .

just you need to change your approach like create the empty list and add all the index into it from where you have to delete the value Staring from bottom to top like from end of list so that it can not effect the index of the list by deleted value and after loop you can delete it using the new empty list which contain the list of all the values which should be deleted.

Upvotes: 2

DrMistry
DrMistry

Reputation: 331

You can't modify the collection you're iterating over with the foreach - please see this question for more information.

Upvotes: 1

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