Interview Q&A

Short answer: Practical use cases. Properties not defined in your CLR classes but tracked by EF Core. Useful for storing metadata like CreatedBy, LastModified, or foreign keys without cluttering domain models.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: A filter automatically applied to all queries on an entity. Useful for soft deletes, multi-tenancy (filtering by tenant ID), or data partitioning.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: When/why to use it? A filter automatically applied to all queries on an entity. Useful for soft deletes, multi-tenancy (filtering by tenant ID), or data partitioning.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use .AsNoTracking() for read-only queries. Avoid over-fetching: only select needed columns (Select). Use eager loading wisely (Include). Minimize round trips by batching operations. Use compiled queries for repeated query patterns.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: EF Core batches multiple commands into a single database round trip when possible. Improves performance by reducing network overhead.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: How does EF Core handle batch operations? EF Core batches multiple commands into a single database round trip when possible. Improves performance by reducing network overhead.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use pagination (Skip, Take). Use streaming APIs like IAsyncEnumerable<T> with EF Core 5+. Avoid loading all data into memory at once.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: EF Core doesn’t have built-in caching for query results. Use second-level caching libraries (like EFCoreSecondLevelCacheInterceptor). Use application-level caching (MemoryCache, Redis) strategically.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use FromSqlRaw or ExecuteSqlRaw to execute raw SQL. Map results to entities or DTOs. Use for performance-critical or legacy operations not easily expressed in LINQ.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: SQL Server, PostgreSQL, MySQL — differences, limitations? Providers abstract database-specific implementations. Each supports different features & SQL dialects. Some features may not be supported on all providers (e.g., some EF Core features are provider-specific).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Migrations support may be limited or unavailable. May require manual scripts or provider-specific tooling. Consider NoSQL-specific approaches for schema changes.

Real-world example (ShopNest)

When ShopNest adds a DiscountCode column, you create a migration, review the SQL, then apply it on staging before production.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use shadow properties or explicit properties for timestamps. Override SaveChanges() to set audit fields. Use global query filters for soft delete support.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Mark entities as deleted without physically removing them. Implemented using a boolean flag and global query filters to exclude “deleted” records.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Implementation strategies in EF Core? Mark entities as deleted without physically removing them. Implemented using a boolean flag and global query filters to exclude “deleted” records.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: EF Core can track foreign keys without them being defined in your model as properties. Useful for cleaner domain models.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Configure relationships explicitly. HasOne / WithMany to define navigation properties and cardinality. Offers fine control beyond Data Annotations.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Convert CLR types to database-compatible types and vice versa. Example: storing an enum as a string or encrypted data.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Complex types that don’t have their own identity and lifecycle. Useful for grouping related properties (like Address inside a Customer).

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: When to use them? Complex types that don’t have their own identity and lifecycle. Useful for grouping related properties (like Address inside a Customer).

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Private fields in your entity class mapped by EF Core instead of public properties. Useful for encapsulating domain logic and controlling property access. Transactions, Concurrency, Security

Example code

Private fields in your entity class mapped by EF Core instead of public properties. Useful for encapsulating domain logic and controlling property access. Transactions, Concurrency, Security

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: EF Core automatically wraps SaveChanges() calls in a transaction. Ensures all changes are committed atomically. For multiple SaveChanges() calls, transactions need manual handling.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Rollback) Use DbContext.Database.BeginTransaction() to start a transaction. Call Commit() to save changes or Rollback() to undo.

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: (BeginTransaction, Commit, Rollback) Use DbContext.Database.BeginTransaction() to start a transaction.

Explain a bit more

Call Commit() to save changes or Rollback() to undo. Useful for combining multiple operations that should succeed or fail as a unit. using var transaction = context.Database.BeginTransaction(); try { // Perform multiple operations context.SaveChanges(); transaction.Commit(); } catch { transaction.Rollback(); throw; }

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Assumes conflicts are rare; detects conflicts when saving. Uses concurrency tokens (e.g., timestamp or row version) to detect if data was changed by another process.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: How to implement it? Assumes conflicts are rare; detects conflicts when saving. Uses concurrency tokens (e.g., timestamp or row version) to detect if data was changed by another process. EF Core throws DbUpdateConcurrencyException if a conflict occurs.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.