Entity Framework Interview Questions and Answers

Ques 1. What is Entity Framework (EF)?

Entity Framework (EF) is an object-relational mapping (ORM) framework that enables developers to work with relational data using domain-specific objects.

Ques 2. What is DbContext in Entity Framework?

DbContext is a class in EF that represents a session with the database, allowing you to query and save data.

Ques 3. How can you disable Lazy Loading in Entity Framework?

You can disable Lazy Loading by setting the LazyLoadingEnabled property of the DbContext to false.

Ques 4. How can you perform eager loading using Include method in Entity Framework?

The Include method is used to specify related entities that should be loaded along with the main entity. For example, context.Orders.Include(o => o.Customer).ToList();

Ques 5. What is the purpose of the AsNoTracking method in Entity Framework?

The AsNoTracking method is used to disable change tracking for a specific query, which can improve performance when you only need to read data.

Ques 6. What is the purpose of the [Table] attribute in Entity Framework?

The [Table] attribute is used to specify the table name for an entity when it does not match the default convention.

Example:

[Table("MyCustomTableName")] public class MyEntity { /* properties */ }

Ques 7. Explain the purpose of the [Key] attribute in Entity Framework.

The [Key] attribute is used to specify the primary key property of an entity when it does not match the default convention.

Example:

[Key] public int MyCustomId { get; set; }

Ques 8. Explain the purpose of the [NotMapped] attribute in Entity Framework.

The [NotMapped] attribute is used to specify that a property should not be mapped to a column in the database.

Example:

[NotMapped] public string CalculatedProperty { get { /* calculation logic */ } }

Ques 9. What is the purpose of the DbSet.Find method in Entity Framework?

The DbSet.Find method is used to retrieve an entity from the database by its primary key value.

Example:

var entity = context.MyEntities.Find(1);

Ques 10. What is the purpose of the [MaxLength] attribute in Entity Framework?

The [MaxLength] attribute is used to specify the maximum length of a string or binary property when creating the database schema.

Example:

[MaxLength(50)] public string Name { get; set; }

Ques 11. What is the purpose of the ToListAsync method in Entity Framework?

The ToListAsync method is used to asynchronously execute a query and return the result as a List.

Example:

var result = await context.Entities.ToListAsync();

Ques 12. What is the purpose of the [Required] attribute in Entity Framework?

The [Required] attribute is used to specify that a property is required and must have a non-null value when saving to the database.

Example:

[Required] public string Name { get; set; }

Ques 13. Explain the purpose of the [StringLength] attribute in Entity Framework.

The [StringLength] attribute is used to specify the maximum length of a string property when creating the database schema.

Example:

[StringLength(100)] public string Description { get; set; }

Ques 14. Explain the purpose of the Add method in Entity Framework.

The Add method is used to add a new entity to the context, marking it as Added, and inserting it into the database when SaveChanges is called.

Example:

context.Entities.Add(newEntity);

Ques 15. What is the purpose of the Remove method in Entity Framework?

The Remove method is used to mark an entity as Deleted in the context, and the entity will be deleted from the database when SaveChanges is called.

Example:

context.Entities.Remove(entityToDelete);

Ques 16. Explain the purpose of the AsQueryable method in Entity Framework.

The AsQueryable method is used to convert an IEnumerable to IQueryable, enabling the use of LINQ expressions to query a collection.

Example:

var queryable = list.AsQueryable();

Ques 17. What is the purpose of the Set method in Entity Framework?

The Set method is used to get a DbSet for a given entity type, allowing you to perform database operations on that entity type.

Example:

var set = context.Set();

Ques 18. Explain the purpose of the FindAsync method in Entity Framework.

The FindAsync method is used to asynchronously retrieve an entity from the database by its primary key value.

Example:

var entity = await context.MyEntities.FindAsync(1);