Crud Operation Examples

CRUD (CREATE,READ,UPDATE,DELETE)operation spring program to find student by id with get and post request

Example-1:

Here’s an example Spring program that demonstrates how to perform CRUD operations and implement GET and POST requests to find a student by their ID.

First, let’s define the Student class that represents a student and their details.

First, let’s define the Student class that represents a student and their details.

public class Student {
  private int id;
  private String name;
  private String email;
  // getters and setters
}

Next, let’s create a StudentController class that handles the requests.

@RestController
@RequestMapping("/students")
public class StudentController {

  private Map<Integer, Student> students = new HashMap<>(); // a collection to store students

  // POST request to add a new student
  @PostMapping("/add")
  public ResponseEntity<Student> addStudent(@RequestBody Student student) {
      students.put(student.getId(), student);
      return ResponseEntity.ok(student);
  }

  // GET request to find a student by ID
  @GetMapping("/{id}")
  public ResponseEntity<Student> getStudentById(@PathVariable int id) {
      if (students.containsKey(id)) {
          return ResponseEntity.ok(students.get(id));
      }
      return ResponseEntity.notFound().build();
  }
}

In this class, we have defined two methods - addStudent and getStudentById.
The addStudent method handles a POST request to add a new student to the collection. It takes in a Student object in the request body, adds it to the students collection, and returns the same student object with an HTTP status code of 200 (OK).
The getStudentById method handles a GET request to find a student by their ID. It takes in the id of the student in the path variable, checks if the students collection contains a student with that ID, and returns the student object with an HTTP status code of 200 (OK) if found, or a 404 (Not Found) status code if not found.

Finally, let’s define the main class that runs the Spring application.

@SpringBootApplication
public class StudentApplication {

  public static void main(String[] args) {
      SpringApplication.run(StudentApplication.class, args);
  }
}

That’s it! You can now run the application and test it out using a REST client or a web browser. Here are a few sample requests:
To add a new student: ``` java POST http://localhost:8080/students/add Content-Type: application/json

{ “id”: 1, “name”: “John Doe”, “email”: “johndoe@example.com” }

* To find a student by ID:
``` java
GET http://localhost:8080/students/1

This should return the following response:

{
  "id": 1,
  "name": "John Doe",
  "email": "johndoe@example.com"
}