@RequestParam Vs @QueryParam Vs @PathParam Vs @PathVariable in REST API

@PathParam & @QueryParam are NOT Spring Annotations. They are JAX-RS annotation. Whereas only @RequestParam & @PathVariable are SPRING Annotations!!

 Now that half the problems are solved, lets continue on this journey.

1. @RequestParam(Spring)

@RequestParam is used to extract query parameters from the URL. It is typically used to handle parameters that are part of the URL query string.

Example URL Usage:

http://example.com/api/users?id=123&name=John

Controller REST Call:

@RestController
@RequestMapping("/api")
public class UserController {

@GetMapping("/users")
    public ResponseEntity<String> getUserByIdAndName(
            @RequestParam("id") String id, 
            @RequestParam("name") String name) {

        return ResponseEntity.ok("User ID: " + id + ", Name: " + name);
    }
}

2. @PathVariable (Spring)

@PathVariable is used to extract values from URI templates. These values are part of the path segment of the URL.

Example URL Usage:

http://example.com/api/users/123/John

Controller REST Call:

@RestController
@RequestMapping("/api")
public class UserController {

@GetMapping("/users/{id}/{name}")
    public ResponseEntity<String> getUserByIdAndName(
            @PathVariable("id") String id, 
            @PathVariable("name") String name) {

        return ResponseEntity.ok("User ID: " + id + ", Name: " + name);
    }
}

3. @QueryParam (JAX-RS's equivalent of Spring's @RequestParam)

@QueryParam is used in JAX-RS (Java API for RESTful Web Services) for extracting query parameters from the URL. It is not a Spring annotation but can be used in JAX-RS implementations. In Spring, @RequestParam is the equivalent.

Example URL Usage:

http://example.com/api/users?id=123&name=John

Controller REST Call (JAX-RS):

@Path("/api")
public class UserResource {

@GET
    @Path("/users")
    public ResponseEntity<String> getUserByIdAndName(
            @QueryParam("id") String id, 
            @QueryParam("name") String name) {

        return ResponseEntity.ok("User ID: " + id + ", Name: " + name);
    }
}

4. @PathParam (JAX-RS's equivalent of Spring's @PathVariable)

Binds a path parameter from the URI to a method parameter.

It is used to extract path parameters from the URI in JAX-RS (Java API for RESTful Web Services) implementations like Jersey or RESTEasy.

Example URL Usage:

http://example.com/api/users/123

Controller REST Call:

@Path("/api")
public class UserResource {

    @GET
    @Path("/users/{id}")
    public ResponseEntity<String> getUserById(
            @PathParam("id") String id) {
        return ResponseEntity.ok("User ID: " + id);
    }
}

Summary:

• @RequestParam: Extracts query parameters from the URL's query string.
• @QueryParam: JAX-RS equivalent of @RequestParam, used for extracting query parameters in JAX-RS applications.
• @PathParam: JAX-RS annotation used for extracting path parameters from the URI.
• @PathVariable: Spring annotation used for extracting path parameters from the URI.