Question

I have the following code

return lStoredRecords.Select(u => 
                                 u.sCardId == sCardId && 
                                 u.rtMode == eRecordType &&
                                 u.dtTime >= DateTime.Now.AddMinutes(-15.0)).Any();

But for some reason it always returns True,

lStoredRecords contains one record such that it’s dtTime doesn’t satisfy the above condition – so I was expecting the above line of code to return False

Any ideas?

Answer 1

Firstly, it’s not clear why you’re using Select at all. I’d expect you to just use Any on its own, specifying the predicate as an argument.

Secondly, if lStoredRecords has any records at all, this will always return true – Any() without a predicate just returns whether there are any records in the input sequence, and Select is just going to project an input value to an ouptut value – it’s not doing any filtering at all. If you were expecting to filter, you should have been using Where.

Thirdly, it’s not clear that you want Any in the first place. From your question:

lStoredRecords contains one record such that it’s dtTime doesn’t satisfy the above condition – so I was expecting the above line of code to return False

If you want it to return false if any of the records fails to satisfy a condition, you should almost certainly be using All instead – you want to check whether all the input values match your condition.

So basically you want:

return lStoredRecords.All(u => u.sCardId == sCardId && 
                               u.rtMode == eRecordType &&
                               u.dtTime >= DateTime.Now.AddMinutes(-15.0));