My First Full Stack Spring Boot / JQuery Application

Part 4 - Creating a Controller

Create a Controller

• Controllers define how to handle incoming requests from and outgoing responses to a client.
• Controllers provides all of the necessary endpoints to access and manipulate respective domain objects.
  • REST resources are identified using URI endpoints.
• The aggregate of all controller endpoints exposed by a webserver is known as the webserver’s web API.

@Controller
public class PersonController {
    private PersonService service;

    @Autowired
    public PersonController(PersonService service) {
        this.service = service;
    }

    @PostMapping(value = "/create")
    public ResponseEntity<Person> create(@RequestBody Person person) {
        return new ResponseEntity<>(service.create(person), HttpStatus.CREATED);
    }

    @GetMapping(value = "/read/{id}")
    public ResponseEntity<Person> readById(@PathVariable Long id) {
        return new ResponseEntity<>(service.readById(id), HttpStatus.OK);
    }

    @GetMapping(value = "/readAll")
    public ResponseEntity<List<Person>> readAll() {
        return new ResponseEntity<>(service.readAll(), HttpStatus.OK);
    }

    @PutMapping(value = "/update/{id}")
    public ResponseEntity<Person> updateById(
            @PathVariable Long id,
            @RequestBody Person newData) {
        return new ResponseEntity<>(service.update(id, newData), HttpStatus.OK);
    }

    @DeleteMapping(value = "/delete/{id}")
    public ResponseEntity<Person> deleteById(@PathVariable Long id) {
        return new ResponseEntity<>(service.deleteById(id), HttpStatus.OK);
    }
}

constructor

create Method

• The POST verb functionality in a create method allows us to add a new Person record.
• Take note that the method
  • has a parameter of type @RequestBody Person person
    • @RequestBody tells Spring that the entire request body needs to be converted to an instance of Person
  • delegates the Person persistence to PersonRepository’s save method called by the PersonService’s create method.

@PostMapping(value = "/create")
public ResponseEntity<Person> create(@RequestBody Person person) {
    return new ResponseEntity<>(service.create(person), HttpStatus.CREATED);
}

readById Method

• The code snippet below allows us to access an individual Person.
• The value attribute in @GetMapping takes a URI template /read/{id}.
• The placeholder {id} along with @PathVarible annotation allows Spring to examine the request URI path and extract the pollId parameter value.
• Inside the method, we use the PersonService’s readById finder method to retrieve the respective Person from the PersonRepository and pass the result to a ResponseEntity.

@GetMapping(value = "/read/{id}")
public ResponseEntity<Person> readById(@PathVariable Long id) {
    return new ResponseEntity<>(service.readById(id), HttpStatus.OK);
}

readAll Method

• The code snippet below allows us to access all Person records.
• The value attribute in @GetMapping takes a URI template /read/{id}.
• The placeholder {id} along with @PathVarible annotation allows Spring to examine the request URI path and extract the pollId parameter value.
• Inside the method, we use the PersonService’s readById finder method to retrieve the respective Person from the PersonRepository and pass the result to a ResponseEntity.

@GetMapping(value = "/readAll")
public ResponseEntity<List<Person>> readAll() {
    return new ResponseEntity<>(service.readAll(), HttpStatus.OK);
}

update Method

• The code snippet below enables us to update a Person with new data.

@PutMapping(value = "/update/{id}")
public ResponseEntity<Person> updateById(
        @PathVariable Long id,
        @RequestBody Person newData) {
    return new ResponseEntity<>(service.update(id, newData), HttpStatus.OK);
}

deleteById Method

• The code snippet below enables us to delete a Person

@DeleteMapping(value = "/delete/{id}")
public ResponseEntity<Person> deleteById(@PathVariable Long id) {
    return new ResponseEntity<>(service.deleteById(id), HttpStatus.OK);
}