[FIXED] REST API delete HTTP request in Spring Boot

Issue

I'm learning REST API. I'm trying to delete an element from the list. I tried but getting an error on the postman. Can anyone help me where I went wrong? Also, can we return the object after deleting it? I also tried it but I think I'm messing up in delete code. So it was not working.

Here is the controller code:

@RestController
public class SpringRestController {
    
@Autowired
private CourseService courseService;

//Get the courses
@GetMapping("/courses")
public List<Course> getCourses()
{
    return this.courseService.getCourses();
}

@GetMapping("/courses/{courseId}")
public Course getCourse(@PathVariable String courseId)
{
    return this.courseService.getCourse(Long.parseLong(courseId));
}

//Add a course
@PostMapping("/courses")
public Course addCourse(@RequestBody Course course)
{
    return this.courseService.addCourse(course);
}

@PutMapping("/courses/{courseId}")
public Course updateCourse(@PathVariable String courseId,@RequestBody Course course)
{
    return this.courseService.updateCourse(Long.parseLong(courseId),course);
}

@DeleteMapping("/courses/{courseId}")
public List<Course> deleteCourse(@PathVariable String courseId)
{
    return (List<Course>) this.courseService.deleteCourse(Long.parseLong(courseId));    
    
}
}

Here is the service implementation of the request :

@Service
public class CourseServiceImpl implements CourseService {

List<Course> list;

public CourseServiceImpl()
{
    list = new ArrayList<>();
    list.add(new Course(145l,"Java Array","Basic Array"));
    list.add(new Course(123l,"Java Constructor","Basic Constructor"));
}

@Override
public List<Course> getCourses() {
    return list;
}

@Override
public Course getCourse(long courseId) {
    Course c = null;
    for(Course course:list)
    {
        if(course.getId()==courseId)
        {
            c=course;
            break;
        }
    }
    return c;
}

@Override
public Course addCourse(Course course) {
    list.add(course);
    return course;
}

@Override
public Course updateCourse(long courseId,Course course) {
    Course c = null;
    for(Course cour:list)
    {
    if(cour.getId()==courseId)
    {
        cour.setTitle(course.getTitle());
        cour.setDescription(course.getDescription());
        c=cour;
    }
    }   
    return c;       
}

@Override
public List<Course> deleteCourse(long courseId) {
    
    for(Course course:list)
    {
        if(course.getId()==courseId)
        {           
            list.remove(course);
        }
    }       
    return list;        
}
}

No errors in spring boot.

Error I got in postman is here :

{
"timestamp": "2021-07-13T03:36:27.454+00:00",
"status": 500,
"error": "Internal Server Error",
"path": "/courses/786"
}

Solution

According to your Code, foreach cannot used to remove item, you should use Iterator.

for (Iterator<Course> iterator = list.iterator(); iterator.hasNext(); ) {
    Course course = iterator.next();
    if (course.getId() == courseId) {
        iterator.remove();
    }
}

Answered By - Daiql