How to lookup entities in EntityFramework 4 by a finder interface? (works in LinqToSql)?

I think the error there lies in the way you are trying to compare the TKey generic. Since TKey is a complex type, the == operator has to be explicitly implemented in order to make this comparison. Now with the TKey generic, there is no guarantee that it is.

Perhaps there is another generic constraint you can place on TKey to ensure that there is a comparison method available?

Yes I think this is the crux of the problem and hence why I tried to constrain TKey to value types where == should be available. Clearly this isn't working as I intended though. – Joshua Hayes Nov 4 '10 at 6:12 Constraining to a struct doesn't ensure value the equality operator is in play.

For lack of a better solution you could write an evaluator function that reflects the common properties and if they all match then you have equality. Or you can serialize both and do string comparison. Not elegant solutions either of em though.

– Slappy Nov 4 '10 at 6:37 msdn.microsoft. Com/en-us/library/ms173110. Aspx – Slappy Nov 4 '10 at 6:41 Thanks for the update slappy.

You are correct about the struct contraint. It was a long short. I cannot believe there wouldn't be a way to achieve what works fine in LinqToSql, in the entity framework.

However, as for constraining to value types I believe its not actually possible. So I'm a bit stumped here... – Joshua Hayes Nov 4 '10 at 11:00.

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