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POHow can I convert anonymous type to strong type in LINQ?
 

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  1. POHow can I convert anonymous type to strong type in LINQ?
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    <p>I have an array of ListViewItems ( <code>ListViewItem[]</code> ), where I store a <code>SalesOrderMaster</code> object in each ListViewItem.Tag for later reference.</p> <p>I have some code that right now, goes through each <code>ListViewItem</code> safely casts the .Tag property into a SalesOrderMaster object, then adds that object to a collection of SalesOrders, only after checking to make sure the order doesn't already exist in that collection.</p> <p>The process to <strong>compare</strong> sales orders is expensive, and I would like to convert this to a LINQ expression for clarity and performance. ( I also have the <a href="http://www.microsoft.com/downloads/details.aspx?FamilyId=348F73FD-593D-4B3C-B055-694C50D2B0F3&amp;displaylang=en" rel="noreferrer">Parallel Extensions to .NET Framework 3.5</a> installed so I can use that to further improve LINQ performance)</p> <p>So without further ado: This is what I have, and then what I want. ( what I want won't compile, so I know I am doing something wrong, but I hope it illustrates the point )</p> <p>What I have: ( Slow )</p> <pre><code>foreach (ListViewItem item in e.Argument as ListViewItem[]) { SalesOrderMaster order = item.Tag as SalesOrderMaster; if ( order == null ) { return; } if (!All_SalesOrders.Contains(order)) { All_SalesOrders.Add(order); } } </code></pre> <p>What I want: ( Theory )</p> <pre><code> List&lt;SalesOrderMaster&gt; orders = (from item in (e.Argument as ListViewItem[]).AsParallel() select new { ((SalesOrderMaster)item.Tag) }).Distinct(); </code></pre> <p>EDIT: I know the cast is cheap, I said the "Compare", which in this case translates to the .Contains(order) operation</p> <p>EDIT: Everyone's answer was awesome! I wish I could mark more than one answer, but in the end I have to pick one.</p> <p>EDIT : This is what I ended up with: </p> <pre><code>List&lt;SalesOrderMaster&gt; orders = (from item in (e.Argument as ListViewItem[]) select (SalesOrderMaster) item.Tag).GroupBy(item =&gt; item.Number).Select(x =&gt; x.First()).ToList(); </code></pre>
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