SwiftData Code Review

Quick Reference

Issue Type Reference

@Model, @Attribute, @Relationship, delete rules references/model-design.md

@Query, #Predicate, FetchDescriptor, #Index references/queries.md

@ModelActor, ModelContext, background operations references/concurrency.md

VersionedSchema, MigrationStage, lightweight/custom references/migrations.md

Review Checklist

• Models marked final (subclassing crashes)

• @Relationship decorator on ONE side only (not both)

• Delete rules explicitly set (not relying on default .nullify)

• Relationships initialized to empty arrays, not default objects

• Batch operations used for bulk inserts (append(contentsOf:) )

• @Query not loading thousands of items on main thread

• External values in predicates captured in local variables

• Scalar comparisons in predicates (not object references)

• @ModelActor used for background operations

• PersistentIdentifier/DTOs used to pass data between actors

• VersionedSchema defined for each shipped version

• MigrationPlan passed to ModelContainer

When to Load References

• Reviewing @Model or relationships -> model-design.md

• Reviewing @Query or #Predicate -> queries.md

• Reviewing @ModelActor or background work -> concurrency.md

• Reviewing schema changes or migrations -> migrations.md

Review Questions

• Could this relationship assignment cause NULL foreign keys?

• Is @Relationship on both sides creating circular references?

• Could this @Query block the main thread with large datasets?

• Are model objects being passed between actors unsafely?

• Would schema changes require a migration plan?