What is entity class in spring boot?

What is entity class in spring boot: In Spring Boot, an entity class is a Java class that represents a table in a database. It typically maps the fields of the table to the properties of the class, and the instances of the class represent the rows in the table.

To define an entity class in Spring Boot, you can use the @Entity annotation on the class. This annotation tells Spring that the class is an entity, and it should be mapped to a database table. You can also use other annotations like @Id to specify the primary key of the table and @Column to map the columns of the table to the properties of the class.

Here is an example of an entity class in Spring Boot:

@Entity
public class User {
    
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    
    @Column(nullable = false)
    private String name;
    
    @Column(nullable = false)
    private String email;
    
    // getters and setters
}

In this example, we have defined a User entity class that has three properties: id, name, and email. The @Id annotation specifies that the id property is the primary key of the table, and the @Column annotation specifies that the name and email properties are columns in the table. The @GeneratedValue annotation specifies that the id property should be generated automatically by the database.

Once you have defined an entity class, you can use it with Spring’s JPA (Java Persistence API) to perform CRUD (Create, Read, Update, Delete) operations on the database. You can also use it with other Spring Boot features like Spring Data JPA and Spring MVC to build a complete web application.

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What is entity annotation in spring boot?

In Spring Boot, the @Entity annotation is used to mark a Java class as an entity. An entity is a Java class that represents a table in a relational database, and the @Entity annotation is used to map the properties of the Java class to the columns of the database table.

When you use the @Entity annotation on a Java class, Spring Boot automatically creates a table in the database with the same name as the Java class. The properties of the Java class are mapped to columns in the table, and the instances of the class represent the rows in the table.

Here is an example of how to use the @Entity annotation in Spring Boot:

@Entity
@Table(name = "employees")
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(nullable = false)
    private String name;

    @Column(nullable = false)
    private String department;

    // getters and setters
}

In this example, we have defined an Employee class as an entity using the @Entity annotation. We have also specified that the table name in the database should be “employees” using the @Table annotation. The @Id annotation is used to specify the primary key of the table, and the @GeneratedValue annotation is used to automatically generate the primary key value. The @Column annotation is used to map the properties of the Java class to columns in the database table.

When you use JPA (Java Persistence API) to perform database operations on the Employee entity, Spring Boot will automatically create the employees table in the database if it does not already exist, and it will map the properties of the Employee class to the columns of the employees table. You can use the @Entity annotation to define other entities in your Spring Boot application as needed.

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Spring Boot Coding interview questions

Here are some sample Spring Boot coding interview questions:

1. How would you create a REST API endpoint in Spring Boot that returns a list of all users from a database table?
2. How would you implement a custom exception handler in Spring Boot to handle exceptions thrown by your application and return appropriate error responses to the client?
3. How would you configure Spring Security in a Spring Boot application to restrict access to certain endpoints based on user roles?
4. How would you implement a background task that runs periodically in a Spring Boot application, such as sending email reminders to users?
5. How would you configure a Spring Boot application to use an external properties file for configuration, such as a database connection URL or API keys?
6. How would you implement a caching mechanism in a Spring Boot application to improve performance and reduce database load?
7. How would you write unit tests for a Spring Boot controller that interacts with a database, using a test database to avoid modifying production data?
8. How would you implement a data validation mechanism in a Spring Boot application to ensure that user input is valid and meets certain criteria?
9. How would you integrate a third-party library or API into a Spring Boot application, such as a payment gateway or social media platform?
10. How would you implement a file upload endpoint in a Spring Boot application, allowing users to upload files and storing them on a server or cloud storage service?

These are just a few examples of the types of Spring Boot coding interview questions you may encounter. It is important to have a strong understanding of Spring Boot and its various features, as well as experience implementing common tasks and functionalities.