Important Annotations

@SpringBootTest & @Test

@SpringBootTest
public class CourseRepositoryTest {

    @Autowired
    private CourseRepository courseRepository;

    @Test
    public void saveCourse() {
        List<Course> courses = courseRepository.findAll();
        System.out.println("courses = " + courses);
    }

@Component

• It is an annotation that allows Spring to automatically detect our custom beans
• Can only be annotate on a class
• @Service and @Repository are special cases of @Component.

@Service

Service Components are the class file which contains @Service annotation. These class files are used to write business logic in a different layer, between @RestController class and @Repository

@Repository

@Repository annotates classes at the persistence layer, which will act as a database repository.

@Autowired

• Enables automatic dependency injection. In other words, by declaring all the bean dependencies in a Spring configuration file, Spring container can auto wire relationships between collaborating beans. This is called Spring bean auto-wiring.

@Component
public class FooService {  
    @Autowired
    private IDependency dependency;
}

@Primary

• There's another annotation called @Primary that we can use to decide which bean to inject when ambiguity is present regarding dependency injection.
• This annotation defines a preference when multiple beans of the same type are present.

@EnableConfigurationProperties

@EnableConfigurationProperties(SecretConfigProp.class)

To load config from Class, refer below annotation

@ConfigurationProperties("secret")

@ConfigurationProperties("secret")
public record SecretConfigProp(String username, String password, String authToken) {
}

```spring-boot-properties
secret.authToken:my_auth_token
secret.username:myusername

spring.config.import:optional:secrets.properties
```

```java-properties
secret.password=password
```