[FIXED] How to use unit of work in rest controller properly?

Issue

public interface CourseRepo extends CrudRepository<Course, Long> {

}

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor 
 public class UnitOfWork {

    CourseRepo courses;
    StudentRepository students;
    StudyProgramRepository studyPrograms;
    StudySchemeRepo studySchemes;
    FeeStructureRepository feeStructures;
}

@RestController
public class TestController {
    
    @Autowired
    UnitOfWork uow;
    

    @GetMapping("/addcr")
    public String addCourse() {
        
        Course cr = new Course();
        cr.setTitle("DingDong course");
        uow.getCourses().save(cr);

        return "course Added..!!" ;
    }

APPLICATION FAILED TO START
***************************

Description:

Field uow in com.srs.TestController required a bean of type 'com.srs.uow.UnitOfWork' that could not be found.

The injection point has the following annotations:
    - @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'com.srs.uow.UnitOfWork' in your configuration.

if i remove autowired and add a bean

@RestController
public class TestController {
    
    @Bean
    public UnitOfWork uow() {
        return new UnitOfWork();
    }

    @GetMapping("/addcr")
    public String addCourse() {
        
        Course cr = new Course();
        cr.setTitle("DingDong course");
        uow().getCourses().save(cr);

        return "course Added..!!" ;
    }

java.lang.NullPointerException: Cannot invoke "com.srs.jpa.CourseRepo.save(Object)" because the return value of "com.srs.uow.UnitOfWork.getCourses()" is null

i tried both autowired and in this case how can i use autowired or bean properly ?

Solution

Your class need to be annotated with @Component to be used with DI provider by @Autowired annotation

For the same reason each repository of your class need to be annotated with @Autowired

Answered By - Luca Riccitelli
Answer Checked By - Terry (JavaFixing Volunteer)