REST API delete HTTP request in Spring Boot

Question

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"
}

There's not enough information in your question for anyone to help you. Please post the error text from postman and any logs from your server. Have a look at how to ask and or how to create a minimal reproducible example. — Hopey One
– Hopey One, Commented Jul 13, 2021 at 3:57
This is the error in postman : { "timestamp": "2021-07-13T03:36:27.454+00:00", "status": 500, "error": "Internal Server Error", "path": "/courses/786" } — Ryuk
– Ryuk, Commented Jul 13, 2021 at 3:58

Daiql · Accepted Answer · 2021-07-13 05:02:33Z

2

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 Jul 13, 2021 at 5:02

Daiql

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1 Comment

Ryuk Over a year ago

I need at least 15 reputations to cast a vote. But Thank you very much sir. Can you tell me the reason why we this method?

S. Anushan · Accepted Answer · 2021-07-13 05:01:33Z

1

Remove the object using index not like object. That the issue.

list.remove(index of the object);


Iterator<Object> li = list;

While(li.hasNext()){
 Object obj= li.next();
 If(courseId==id){
 Ii.remove();
 }
}

edited Jul 13, 2021 at 5:01

answered Jul 13, 2021 at 4:55

S. Anushan

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1 Comment

Ryuk Over a year ago

I need at least 15 reputations to cast a vote. But Thank you very much sir.

Akshay Tomar · Accepted Answer · 2021-07-13 08:43:16Z

0

You are trying to pass courseId as "786" which is not present in your ArrayList. If you still want to delete it, then add a course with courseId "786" in your Course list.

When I tried deleting course with id 786 it shows all other courses because courseId 786 is not present in the list.

edited Jul 13, 2021 at 8:43

answered Jul 13, 2021 at 6:18

Akshay Tomar

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Comments

tushar · Accepted Answer · 2021-07-13 04:12:20Z

-1

Check course id 786 is present in your list or not.

answered Jul 13, 2021 at 4:12

tushar

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2 Comments

Ryuk Over a year ago

I implemented an post http request also that's workiing fine. I added course with 786 course id , then I was trying to delete the same course with id 786 just to check if its deleting or not

S. Anushan Over a year ago

If courseId present or not that's not issue

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