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MigratingTo1.4.md

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Migrating to 1.4

SQLiteData 1.4 introduces a new tool for tying the lifecycle database subscriptions to the lifecycle of the surrounding async context, but it may incidentally cause "Result of call … is unused" warnings in your project.

Overview

The load method defined on @FetchAll / @FetchOne / @Fetch all now return a discardable result, FetchSubscription. Awaiting the FetchSubscription/task of that result ties the lifecycle of the subscription to the database to the lifecycle of the surrounding async context, which can help views to automatically unsubscribe from the database when they are not visible.

However, when used with withErrorReporting you are likely to get the following warning:

private func updateQuery() async {
  // ⚠️ Result of call to 'withErrorReporting(_:to:fileID:filePath:line:column:isolation:catching:)' is unused
  await withErrorReporting {
    try await $rows.load(…)
  }
}

This is happening because although load has a discardable result, Swift does not propagate that to withErrorReporting, and so Swift thinks you have an unused value. To fix you will need to explicitly ignore the result with _ = :

private func updateQuery() async {
  _ = await withErrorReporting {
    try await $rows.load(…)
  }
}