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Top 20 Entity Framework Interview Questions and Answers

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Top 20 Entity Framework Interview Questions and Answers
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What is Entity Framework?

Entity Framework is an open-source Object Relational Mapper for .NET applications developed by Microsoft. It allows developers to streamline mapping between various objects in software with the help of tables and columns. It uses objects of domain-specific classes but does not focus on the original database tables and columns that store the data. This allows ease of working with an abstraction of a higher level while creating and maintaining data-oriented applications.

List some Entity Framework pros and cons.

The pros of the Entity Framework are-

  • It has brilliant prototypes that allow writing of object-oriented codes.
  • It allows auto migrations that make setting up or modifying a database easy and timesaving.
  • It can shorten codes with the help of alternate commands making the job of developers simpler.

The cons of the Entity Framework are-

  • Sometimes things can become complicated, especially if the developer is not using raw SQL codes.
  • Entity Framework is a slower form of Object Relational Mapper.
  • It directs the shape of the model, especially for more complex projects. Also, cleaning a model is not without an ORM technology.

Describe the architecture of the Entity Framework?

The architecture of Entity Framework has the following components-

  • Entity Data Model (EDM): EDM has three parts - a conceptual model, storage model, and mapping. The conceptual model includes the model class along with their relationships and is independent of the database table. The storage model is a part of the database design model and contains tables, stored procedures, views, relationships, and keys. Mapping refers to the information regarding the mapping of the conceptual model to the storage model.
  • LINQ to Entities (L2E): L2E is a query language with which queries against the object can be written to returns entities according to definitions in the conceptual model.
  • Entity SQL: Entity SQL is an alternative query language that is more difficult than L2E.
  • Object Service: Object service is the entry point into the database for accessing and returning back data. It is liable for converting returned data from an entity client data provider to an entity object structure.
  • Entity Client Data Provider: This layer converts the LINQ-to-Entities queries to SQL queries that the database understands. It also communicates with the ADO.Net data provider to send or recover data from the database.
  • Net Data Provider: This layer uses standard ADO.Net to communicate with the database.

Entity Framework Interview Questions

How does Entity Framework work?

Entity Framework maps domain classes to the database schema translate as well as executes LINQ queries to SQL and tracks the changes in the entities. It also saves the changes to the database.

How to retrieve data from database using Entity Framework in MVC?

The steps to retrieve data from a database using Entity Framework in Model View Controller are-

  • Create a new project.
  • From NuGet package manager, add Entity Framework reference.
  • Create a new class in the model within the table structure.
  • Add connection string in the web.config.connection string name such that it matches with the context.
  • Open the Global.asax.cs class, add the additional namespace of Entity Framework and finally initialize the database.
  • Right Click on Controller folder and then add a new controller and model reference in the section for the namespace.
  • Right Click on the controller name and add the sections you want to view.

What is dbcontext and dbset in Entity Framework?

DbContext is a class in Entity Framework API that forms a connection between a domain or entity class and the database. It is primarily responsible for communicating with the database.

The DbSet is another class that represents an entity set to read, create, update, and delete operations. For the entities that connect to the database tables and views, the context class from DbContext has to contain the DbSet type properties.

What is the difference ado net and Entity Framework?

The differences between ADO.Net and Entity Framework are as follows-

  • Net creates several data layer codes that Entity Framework does not create.
  • Unlike ADO.Net, Entity Framework automatically generates codes for the intermediate layers, data access layers, and mapping codes. This helps to cut down on the development time.
  • Net is faster than Entity Framework based on performance.

What is the difference between LINQ and Entity Framework?

The difference between LINQ and Entity Framework are-

LINQ

Entity Framework

LINQ only operates using SQL Server Database.

Entity Framework uses several databases such as SQL Server, Oracle, MYSQL, DB2, etc.

It only permits one to one mapping between relational tables and entity classes.

It only permits one to one, one to many & many to many mappings between entity classes and relational tables.

It maintains the relation by generating a .dbml.

It first generates an .edmx file and then maintains it using 3 different files- .csdl, .msl and .ssdl.

It finds use in rapid application development along with SQL Server.

It finds use in rapid application development along with SQL Server, DB2, Oracle and MySQL etc.

You can query data with DataContext.

You can query data using DbContext, EntitySQL, and ObjectContext.

It cannot support complex type.

It supports complex type.

It does not create a database from the model.

It can create a database from the model.

It has a tightly coupled approach.

It has a loosely coupled approach.

 Explain POCO classes in Entity Framework?

POCO stands for Plain Old CLR Objects. This class of objects is not dependent on any framework-specific base class, unlike a normal .NET class. They support most of the LINQ queries that Entity Object derived entities support.

What is various entity framework approaches?

The various approaches in Entity Framework are-

  • Database First
  • Model First
  • Code First

What is code first approach in entity framework?

Code First approach in Entity Framework allows the creation of a model and its relations with the help of classes, from which the database is created. Thus, the developer can work in an object-oriented manner without worrying about the structure of the database.

What is database first approach in entity framework?

Database First approach in Entity Framework is used to make an entity model from an existing database and decrease the amount of code that must be written.

What is model first approach in entity framework?

In Model First approach in Entity Framework, the model classes and their relationships are created first with the help of ORM. Then the physical database is generated from the model. Therefore, a diagram of entity and relations are converted into the code model.

Which approach is best in entity framework

The choice of the development approach depends on the project. If the database is present, then it is best to go with the Database First approach. If model classes and database are not present, the Model First is the most suitable. If the developer has domain classes, the Code First approach is the best choice.

What is an edmx file in the entity framework?

A .edmx file in Entity Framework is an XML file that can give definition to conceptual models, storage models, and the mapping between them. It also has information that the ADO.NET Entity Data Model Designer uses to graphically render a model.

How to handle concurrency in entity framework?

Situations where several users access and alter the same data in a particular database, at the same time, it is known as Database concurrency. The mechanisms that safeguard the consistency of data under such circumstances are referred to as concurrency control.

In Entity Framework, the core implements such controls by allowing several changes independently minus the synchronization or locking. In the ideal case, the changes do not interfere with each other. In other cases, the changes are conflicting changes, and only one must succeed.

What is navigation property in the entity framework?

Navigation properties in Entity Framework is a way of representing a foreign key relationship within the database. Navigation properties enable the user to describe the relationships between the entities such that they are coherent in the object-oriented language.

Explain Pluralize and Singularize in Entity Framework?

Pluralize and Singularize in Entity Framework give naming conventions to objects by using the plural ‘s’ to define more than one record.

What are the types of loading are available in entity framework?

The types of loading available in Entity Framework are-

  • Eager Loading
  • Lazy Loading
  • Explicit Loading