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I've been struggling on a way to do this for a while. I have this a listbox in asp.net that I use that looks like :

<asp:ListBox ID="lstLinkedProspect" runat="server" SelectionMode="Multiple" />

What I want to do with it is to be able to select all items I have in a specific table, all except the one that are in the listbox. Not only the selected but all items that are already in the list. I use System.Linq.Dynamic library. Here is what I'm trying to do :

Dim lstProspect = dbConnection.Prospects.Where(If(String.IsNullOrWhiteSpace(SearchFilters.Value), "ProspectId > 0", SearchFilters.Value).ToString) _
                                                .Except(' There goes all the items in the list box)

What I have already tried is :

Dim lstProspect = dbConnection.Prospects.Where(If(String.IsNullOrWhiteSpace(SearchFilters.Value), "ProspectId > 0", SearchFilters.Value).ToString) _
                                                .Except(lstLinkedProspect.Items.Cast(Of ListItem)().Where(Function(x) x.Value).Cast(Of Beans.Prospect))

Is it possible in Linq to get all the items from a table that are not in the listbox? Note that the Value property of the ListItem in the listbox is the ProspectId.

Thanks in advance.

Crushermike
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  • Does dynamic LINQ support `Except`? Could you live with a regular LINQ solution? And what type of LINQ is this? – Gert Arnold Sep 22 '13 at 08:01
  • Yes it does support the Except. One of the advantage is that you can pass a string in the where clause like I did in the sample of code. I can live with a regular Linq solution without any problem. – Crushermike Sep 23 '13 at 13:15
  • Have a look at this post, it might help you out http://stackoverflow.com/questions/853526/using-linq-to-remove-objects-within-a-listt – CheGueVerra Nov 04 '13 at 18:35

1 Answers1

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This is the the code I found to achieve what I was looking for :

Dim lstItems = dbConnection.Prospects.Where(Function(x) ids.Contains(x.ProspectId))
Dim lstProspect = dbConnection.Prospects.Where(If(String.IsNullOrWhiteSpace(SearchFilters.Value),
"ProspectId > 0", SearchFilters.Value).ToString).Except(lstItems)

Hope this can help anyone struggling with that problem.

Crushermike
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