Interview Q&A

Short answer: parameter to facilitate the state change.

Explain a bit more

public interface ITrafficLightState { void Change(TrafficLight light); } Each concrete state class (Red, Green, Yellow) will implement this interface, defining the specific behavior of the traffic light for that state. parameter to facilitate the state change. public interface ITrafficLightState { void Change(TrafficLight light); } Each concrete state class (Red, Green, Yellow) will implement this interface, defining the specific behavior of the traffic light for that state.

Real-world example (ShopNest)

Use a GoF pattern in ShopNest only when it removes duplication or makes a change safer—explain the problem it solves in the interview.

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: n update. public interface INewsPublisher { void Subscribe(IObserver observer); void Unsubscribe(IObserver observer); void Notify(string news); } n update. public interface INewsPublisher { void Subscribe(IObserver observer); void Unsubscribe(IObserver observer); void Notify(string news); } n update. public interface INewsPublisher { void… Subscribe(IObserver observer); void Unsubscribe(IObserver observer); void…

Explain a bit more

Notify(string news); } n update. public interface INewsPublisher { void Subscribe(IObserver observer); void Unsubscribe(IObserver observer); void Notify(string news); }

Real-world example (ShopNest)

When order status changes, observers update email, SMS, and analytics without the Order class knowing each one.

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: And Description() that every coffee component will implement.

Explain a bit more

public interface ICoffee { double Cost(); string Description(); } nd Description() that every coffee component will implement. public interface ICoffee { double Cost(); string Description(); } And Description() that every coffee component will implement. public interface ICoffee { double Cost(); string Description(); } nd Description() that every coffee component will implement. public interface ICoffee { double Cost(); string Description(); }

Real-world example (ShopNest)

Use a GoF pattern in ShopNest only when it removes duplication or makes a change safer—explain the problem it solves in the interview.

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 & how to use it? Explicit loading means loading related data manually, after the main entity is loaded. Use when: You need full control over what and when to load You don’t want automatic lazy loading

Example code

var blog = context.Blogs.First(); context.Entry(blog) .Collection(b => b.Posts) .Load(); context.Entry(blog) .Reference(b => b.Owner) .Load(); ✅ Use .Reference().Load() for single navigation ✅ Use .Collection().Load() for collections

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: The N+1 problem occurs when: 1 query loads N parent entities N additional queries load related entities (1 per parent) Example (lazy loading): foreach (var blog in context.Blogs) { Console.WriteLine(blog.Owner.Name); // triggers a query for each blog } This causes N+1 queries, which can hurt performance significantly.

Explain a bit more

✅ Solution: Use eager loading with .Include() to fetch everything in one query. The N+1 problem occurs when: 1 query loads N parent entities N additional queries load related entities (1 per parent) Example (lazy loading): foreach (var blog in context.Blogs) { Console.WriteLine(blog.Owner.Name); // triggers a query for each blog } This causes N+1 queries, which can hurt performance significantly. ✅ Solution: Use eager loading with .Include() to fetch everything in one query.

Real-world example (ShopNest)

Loading orders with items uses .Include(o => o.Items). Without Include, listing 50 orders can trigger 50 extra queries (N+1).

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 can lazy loading lead to it? The N+1 problem occurs when: 1 query loads N parent entities N additional queries load related entities (1 per parent) Example (lazy loading): foreach (var blog in context.Blogs) { Console.WriteLine(blog.Owner.Name); // triggers a query for each blog } This causes N+1 queries, which can hurt performance significantly. ✅ Solution: Use eager loading with .Include() to fetch everything…

Real-world example (ShopNest)

Loading orders with items uses .Include(o => o.Items). Without Include, listing 50 orders can trigger 50 extra queries (N+1).

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: By default, EF Core uses no automatic loading — it doesn’t lazy-load or eager-load relationships unless you: Use .Include() for eager loading Enable lazy loading proxies Use .Load() for explicit loading This default avoids unintended queries and promotes performance control. EF Core LINQ Queries & Querying

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: Projection transforms entities into custom shapes, e.g., DTOs. var projected = context.Products

Example code

.Select(p => new { p.Name, p.Price }); Useful for: Reducing data load. Returning only needed fields. Mapping to custom types.

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: pplication. Pros: Decouples data access logic from business logic. Easier to mock/test. Encapsulates queries in a single place. Cons: EF Core’s DbContext already acts like a repository and unit of work. Can add unnecessary abstraction and boilerplate. May limit EF Core’s powerful querying features.

Real-world example (ShopNest)

ShopNest registers AppDbContext as scoped. One HTTP request = one context. Never inject it as a singleton.

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: Why use it with EF Core (pros and cons)? Repository Pattern abstracts data access logic, exposing CRUD methods to the application. Pros: Decouples data access logic from business logic. Easier to mock/test. Encapsulates queries in a single place. Cons: EF Core’s DbContext already acts like a repository and unit of work. Can add unnecessary abstraction and boilerplate. May limit EF Core’s powerful querying features.

Real-world example (ShopNest)

ShopNest registers AppDbContext as scoped. One HTTP request = one context. Never inject it as a singleton.

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: Unit of Work maintains a list of operations to be committed as a single transaction. EF Core’s DbContext implements Unit of Work, tracking changes and coordinating commits (SaveChanges()).

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: 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: 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: 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: 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.

Short answer: EF Core creates a dynamic proxy subclass of your entity at runtime. Proxy overrides virtual navigation properties to load related data on-demand. Requires navigation properties to be virtual and package Microsoft.EntityFrameworkCore.Proxies. Proxy intercepts access and triggers loading when property is accessed.

Real-world example (ShopNest)

Loading orders with items uses .Include(o => o.Items). Without Include, listing 50 orders can trigger 50 extra queries (N+1).

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 the dynamic proxy work under the hood? EF Core creates a dynamic proxy subclass of your entity at runtime. Proxy overrides virtual navigation properties to load related data on-demand. Requires navigation properties to be virtual and package Microsoft.EntityFrameworkCore.Proxies. Proxy intercepts access and triggers loading when property is accessed.

Real-world example (ShopNest)

Loading orders with items uses .Include(o => o.Items). Without Include, listing 50 orders can trigger 50 extra queries (N+1).

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: Freelancing success depends on niche clarity, pricing discipline, and reliable delivery. Position yourself around outcomes instead of tasks, and build repeatable systems for sales and execution. This helps you attract better clients and reduce income volatility.

Step-by-step approach

1. Choose a specific service with clear deliverables, timeline, and expected business result.
2. Build proof assets: case studies, testimonials, and sample outputs.
3. Use multiple channels to generate leads: LinkedIn, referrals, platforms, and communities.
4. Run discovery calls to confirm scope, budget, success criteria, and risks.
5. Use contracts, milestone billing, and weekly updates to ensure predictable delivery.

Real-world example

Priya was working at TCS and needed to handle this situation: how to start freelancing. She prepared a clear plan with timelines, ownership, and expected outcomes before speaking to HR and her manager. Rahul, who had recently moved to Razorpay, reviewed her approach and helped her tighten the messaging with measurable results. Within a few weeks, Priya achieved a better career outcome while preserving strong professional relationships.

Numbers & benchmarks

• Collect 30% to 50% advance for fixed-scope projects before starting execution.
• Track your effective hourly rate weekly to prevent underpricing.
• Aim for at least 40% recurring revenue by month six for better stability.

Mistakes to avoid

• Acting without understanding policy, market context, or role expectations.
• Using generic claims instead of measurable evidence and concrete examples.
• Delaying communication and creating last-minute pressure for stakeholders.
• Starting work without a signed scope, payment terms, and revision limits.

Capture major decisions in writing to avoid confusion and future disputes.

Short answer: Freelancing success depends on niche clarity, pricing discipline, and reliable delivery. Position yourself around outcomes instead of tasks, and build repeatable systems for sales and execution. This helps you attract better clients and reduce income volatility.

Step-by-step approach

1. Choose a specific service with clear deliverables, timeline, and expected business result.
2. Build proof assets: case studies, testimonials, and sample outputs.
3. Use multiple channels to generate leads: LinkedIn, referrals, platforms, and communities.
4. Run discovery calls to confirm scope, budget, success criteria, and risks.
5. Use contracts, milestone billing, and weekly updates to ensure predictable delivery.

Real-world example

Karan was working at Razorpay and needed to handle this situation: how to write a project proposal. She prepared a clear plan with timelines, ownership, and expected outcomes before speaking to HR and her manager. Isha, who had recently moved to PhonePe, reviewed her approach and helped her tighten the messaging with measurable results. Within a few weeks, Karan achieved a better career outcome while preserving strong professional relationships.

Mistakes to avoid

• Acting without understanding policy, market context, or role expectations.
• Using generic claims instead of measurable evidence and concrete examples.
• Delaying communication and creating last-minute pressure for stakeholders.
• Skipping rehearsal, which causes weak delivery during interviews or negotiations.

Capture major decisions in writing to avoid confusion and future disputes.

Short answer: Freelancing success depends on niche clarity, pricing discipline, and reliable delivery. Position yourself around outcomes instead of tasks, and build repeatable systems for sales and execution. This helps you attract better clients and reduce income volatility.

Step-by-step approach

1. Choose a specific service with clear deliverables, timeline, and expected business result.
2. Build proof assets: case studies, testimonials, and sample outputs.
3. Use multiple channels to generate leads: LinkedIn, referrals, platforms, and communities.
4. Run discovery calls to confirm scope, budget, success criteria, and risks.
5. Use contracts, milestone billing, and weekly updates to ensure predictable delivery.

Real-world example

Ananya was working at PhonePe and needed to handle this situation: how to create a freelance portfolio. She prepared a clear plan with timelines, ownership, and expected outcomes before speaking to HR and her manager. Vikram, who had recently moved to Infosys, reviewed her approach and helped her tighten the messaging with measurable results. Within a few weeks, Ananya achieved a better career outcome while preserving strong professional relationships.

Numbers & benchmarks

• Collect 30% to 50% advance for fixed-scope projects before starting execution.
• Track your effective hourly rate weekly to prevent underpricing.
• Aim for at least 40% recurring revenue by month six for better stability.

Mistakes to avoid

• Acting without understanding policy, market context, or role expectations.
• Using generic claims instead of measurable evidence and concrete examples.
• Delaying communication and creating last-minute pressure for stakeholders.
• Starting work without a signed scope, payment terms, and revision limits.

Capture major decisions in writing to avoid confusion and future disputes.

Short answer: Freelancing success depends on niche clarity, pricing discipline, and reliable delivery. Position yourself around outcomes instead of tasks, and build repeatable systems for sales and execution. This helps you attract better clients and reduce income volatility.

Step-by-step approach

1. Choose a specific service with clear deliverables, timeline, and expected business result.
2. Build proof assets: case studies, testimonials, and sample outputs.
3. Use multiple channels to generate leads: LinkedIn, referrals, platforms, and communities.
4. Run discovery calls to confirm scope, budget, success criteria, and risks.
5. Use contracts, milestone billing, and weekly updates to ensure predictable delivery.

Real-world example

Meera was working at Infosys and needed to handle this situation: how to scale a freelancing business. She prepared a clear plan with timelines, ownership, and expected outcomes before speaking to HR and her manager. Rohit, who had recently moved to Freshworks, reviewed her approach and helped her tighten the messaging with measurable results. Within a few weeks, Meera achieved a better career outcome while preserving strong professional relationships.

Numbers & benchmarks

• Collect 30% to 50% advance for fixed-scope projects before starting execution.
• Track your effective hourly rate weekly to prevent underpricing.
• Aim for at least 40% recurring revenue by month six for better stability.

Mistakes to avoid

• Acting without understanding policy, market context, or role expectations.
• Using generic claims instead of measurable evidence and concrete examples.
• Delaying communication and creating last-minute pressure for stakeholders.
• Starting work without a signed scope, payment terms, and revision limits.

Capture major decisions in writing to avoid confusion and future disputes.