LINQ | ArgumentOutOfRangeException: Index was out of range

Question

for (int i = 0; i < intFeatureIDs.Count; i++) {
    slots_for = slots_for.Where(s => s.featureSlotMapping.Any(fsm => fsm.featureID == intFeatureIDs[i]));
}

Here, intFeatureID.Count is 2. And throws below exception.

Exception:

Message=An exception was thrown while attempting to evaluate a LINQ query parameter expression. To show additional information call EnableSensitiveDataLogging() when overriding DbContext.OnConfiguring.

Inner Exception 1: ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.

If intFeatureIDs.Count == 1, there is no issue.

Also, If I comment out the for loop, and manually run the code twice, it will work...

slots = slots.Where(s => s.featureSlotMapping.Any(fsm => fsm.featureID == intFeatureIDs[1]));
slots = slots.Where(s => s.featureSlotMapping.Any(fsm => fsm.featureID == intFeatureIDs[2]));

Any comments are much appreciated.

Hi mjwills, thanks for your prompt response. But slots_for is type IQueryable, and toTlist() returns List... it won't work... — DBSQUARED, Feb 10 '18 at 11:48
That's the end of intFeatureIDs... I don't have any other code touching this variable anymore... — DBSQUARED, Feb 10 '18 at 11:48
Will the delay evaluation of LINQ ignore the variable in for loop? Is that what you implied? — DBSQUARED, Feb 10 '18 at 11:50
You are the man!!! I got it, "i" is only visible within the for loop. When delayed, the value is lost. Thank you so much!!! — DBSQUARED, Feb 10 '18 at 11:56

mjwills · Answer 1 · 2018-02-10T22:37:04.867

1

I would recommend changing the code to:

for (int i = 0; i < intFeatureIDs.Count; i++) {
    var bob = intFeatureIDs[i];
    slots_for = slots_for.Where(s => s.featureSlotMapping.Any(fsm => fsm.featureID == bob));
}

This fixes the modified closure issue in your code, and potentially insulates your code against other code (not shown in your sample) that may change / reassign intFeatureIDs.

edited Feb 10 '18 at 22:37

answered Feb 10 '18 at 13:10

mjwills

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LINQ | ArgumentOutOfRangeException: Index was out of range

Exception:

1 Answers1