Optional chaining strange behaviour #329

New Issue

2025-12-29T18:25:44+01:00

adam commented

2025-12-29 18:25:44 +01:00

Originally created by @spacedema on GitHub (May 21, 2020).

Hi!

Noticed strange behaviour while fetching from db, don't know if it is related to core store

// Ok
func getSomeId() -> String? {
  let transaction = DataStack.beginUnsafe()
  return try? transaction.fetchOne(From<Users>().where(\.id == myId))?.otherField?.id
}

// Not Ok, return nil
func getSomeId() -> String? {
  return try? DataStack.beginUnsafe().fetchOne(From<Users>().where(\.id == myId))?.otherField?.id
}

Originally created by @spacedema on GitHub (May 21, 2020). Hi! Noticed strange behaviour while fetching from db, don't know if it is related to core store ``` // Ok func getSomeId() -> String? { let transaction = DataStack.beginUnsafe() return try? transaction.fetchOne(From<Users>().where(\.id == myId))?.otherField?.id } // Not Ok, return nil func getSomeId() -> String? { return try? DataStack.beginUnsafe().fetchOne(From<Users>().where(\.id == myId))?.otherField?.id } ```

adam added the question label 2025-12-29 18:25:44 +01:00

adam closed this issue

2025-12-29 18:25:44 +01:00

adam commented

2025-12-29 18:25:44 +01:00

@JohnEstropia commented on GitHub (May 22, 2020):

My guess it that ARC releases the transaction earlier in the second code. If that's the case, you will probably experience the same thing in the first code when building release (optimized) builds.

You can try

return withExtendedLIfetime(DataStack.beginUnsafe()) { transaction in
    try? transaction.fetchOne(From<Users>().where(\.id == myId))?.otherField?.id
}

@JohnEstropia commented on GitHub (May 22, 2020): My guess it that ARC releases the transaction earlier in the second code. If that's the case, you will probably experience the same thing in the first code when building release (optimized) builds. You can try ```swift return withExtendedLIfetime(DataStack.beginUnsafe()) { transaction in try? transaction.fetchOne(From<Users>().where(\.id == myId))?.otherField?.id } ```

adam commented

2025-12-29 18:25:45 +01:00

@spacedema commented on GitHub (May 22, 2020):

Thanks for the answer, will check it in release build

@spacedema commented on GitHub (May 22, 2020): Thanks for the answer, will check it in release build

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prototype/swift6

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prototype/Swift_4_1

prototype/Swift_4_0

prototype/Swift_3_2

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Reference: starred/CoreStore-JohnEstropia#329