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okilydokily
11,107 PointsCan someone explain what the fact that LINQ queries return a type of IEnumerable has to do with delayed execution?
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1 Answer
Steven Parker
215,954 PointsQueries that create an enumerable don't actually run until you iterate over the enumerable. That's due to the behind-the-scenes "magic" of the framework. So the data isn't fetched until you actually use it.
On the other hand, queries that involve an aggregate (like a sum or average) will occur right away. So will ones that get converted into a conventional storage format like an array or list.
chazber
4,861 Pointschazber
4,861 PointsSteven, I still don't get it. Can you try and break it down even further?
Steven Parker
215,954 PointsSteven Parker
215,954 PointsThe short version is that the framework tries to fetch the data at the last moment so it will delay if it can.
If you don't want it to delay, a common trick is to add a ".ToList()" at the end of a query chain which will cause it to run immediately.