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copied!<p>Your problem is this:</p> <pre><code>as IEnumerable<DataRow> </code></pre> <p>The <code>as</code> keyword performs a safe cast, not a conversion, which it seems like you might think that it's doing. The <code>as</code> keyword is semantically the same as doing this:</p> <pre><code>IEnumerable<DataRow> queryProjects = (IEnumerable<DataRow>)(from DataRow p in db.STREAM_PROJECTs.AsEnumerable() where p.Field<int>("STREAM_ID") == StreamID select new { PROJECT_ID = p.Field<int>("PROJECT_ID"), PROJECT_NAME = p.Field<int>("PROJECT_NAME") }); </code></pre> <p>Except the version with <code>as</code> won't throw an exception when it fails to cast your query object (which is an <code>IQueryable<T></code>, where <code>T</code> is an anonymous type) to an <code>IEnumerable<DataRow></code> (which it isn't).</p> <p>Unfortunately, there is no built-in method that I'm aware of that will take an enumerable of a concrete type (like your anonymous type in this example) and turn it into a <code>DataTable</code>. Writing one wouldn't be too complicated, as you'd essentially need to get the properties reflectively then iterate over the collection and use those properties to create columns in a <code>DataTable</code>. I'll post an example in a few.</p> <p>Something like this, placed in a static class within a namespace that you're <code>using</code>, should provide an extension method that will do what you want:</p> <pre><code>public static DataTable ToDataTable<T>(this IEnumerable<T> source) { PropertyInfo[] properties = typeof(T).GetProperties(); DataTable output = new DataTable(); foreach(var prop in properties) { output.Columns.Add(prop.Name, prop.PropertyType); } foreach(var item in source) { DataRow row = output.NewRow(); foreach(var prop in properties) { row[prop.Name] = prop.GetValue(item, null); } output.Rows.Add(row); } return output; } </code></pre>

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