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POLINQ OrderBy anonymous object with projection comparer
 

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    <p>Ive been trying to get <code>OrderBy</code> in a LINQ statement to work with an anonymous object but have failed by now.</p> <p>I checked these already:<br> <a href="https://stackoverflow.com/questions/5288963/anonymous-icomparer-implementation">Anonymous IComparer implementation</a><br> <a href="https://stackoverflow.com/questions/1381564/c-sharp-linq-sort-quick-way-of-instantiating-icomparer">C# linq sort - quick way of instantiating IComparer</a><br> <a href="https://stackoverflow.com/questions/1301822/how-to-sort-an-array-of-object-by-a-specific-field-in-c/1302185#1302185">How to sort an array of object by a specific field in C#?</a><br></p> <p>I spent a few hours trying different approaches but there has to be something I'm missing.</p> <p>Let's say there's the following class:</p> <pre><code>public class Product { public int Id {get; set;} public string Name {get; set;} public int Popularity {get; set;} public decimal Price {get; set;} } </code></pre> <p>And <code>products</code> is a list of these objects.<br></p> <p>How can I complete this LINQ statement, so that it works with the anonymous object ?<br> To be clear, I know I can do this in a different way but I'd be very interested to learn how to make this particular example work.<br></p> <pre><code>var sortedProducts = products .OrderBy(p =&gt; new {p.Popularity, p.Price}, [IComparer magic goes here]); </code></pre> <p>It seems that it should be possible with an implementation of the <code>ProjectionComparer</code>:<br> <a href="http://code.google.com/p/edulinq/source/browse/src/Edulinq/ProjectionComparer.cs?r=0c583631b709679831c99df2646fc9adb781b2be" rel="nofollow noreferrer">http://code.google.com/p/edulinq/source/browse/src/Edulinq/ProjectionComparer.cs?r=0c583631b709679831c99df2646fc9adb781b2be</a><br></p> <p>Any ideas how to do this ?</p> <p>UPDATE:</p> <p>I did a quick performance test on this - the anonymous comparer solution vs standard orderby.thenby and it seems that the anonymous solution is quite slower which is probably what we might have expected anyway.</p> <pre><code> numProd | Anon | chained orderby clauses 10 000 | 47 ms | 31 ms 100 000 | 468 ms | 234 ms 1 000 000| 5818 ms | 2387 ms 5 000 000| 29547 ms| 12105 ms </code></pre>
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    1. COwhat's your ordering criteria? Are you saying it should be by Popularity first, then by price? Why not do OrderBy on popularity and then ThenBy on price?
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      1. USJames Michael Hare
    2. CO@JamesMichaelHare - let's say higher popularity as a primary factor, lower price as a secondary factor if that makes any difference for the example. EDIT: I know I can do this but I wonder if the approach with the anonymous object will work at all, and if so, I just can't figure out how.
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    3. COWhy use an anonymous object at all in the OrderBy() then? Why not just: `products.OrderByDescending(p => p.Popularity).ThenBy(p => p.Price)`
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