Understanding @RequestParam, @QueryParam, @PathParam, and @PathVariable in Spring Boot

1. @RequestParam

• Used to extract query parameters from the request URL.
• Supports optional and default values.
• Commonly used in GET requests.

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

    @GetMapping("/users")
    public String getUserByName(@RequestParam(name = "name", required = false, defaultValue = "Guest") String name) {
        return "User Name: " + name;
    }
}

Usage:

GET http://localhost:8080/api/users?name=John

Response: User Name: John

If the parameter name is missing, it defaults to "Guest".

2. @QueryParam (From JAX-RS, not used in Spring MVC)

• Works similarly to @RequestParam but is used in JAX-RS (Java EE REST API).
• Spring Boot does not use @QueryParam, instead, @RequestParam should be used.

Example (JAX-RS, Not Spring Boot):

@Path("/users")
public class UserService {

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String getUserByName(@QueryParam("name") String name) {
        return "User Name: " + name;
    }
}

3. @PathParam (From JAX-RS, not used in Spring MVC)

• Used in JAX-RS to extract values from the path variable in the URL.
• Spring Boot does not use @PathParam, instead, @PathVariable should be used.

Example (JAX-RS, Not Spring Boot):

@Path("/users")
public class UserService {

    @GET
    @Path("/{id}")
    @Produces(MediaType.TEXT_PLAIN)
    public String getUserById(@PathParam("id") int id) {
        return "User ID: " + id;
    }
}

4. @PathVariable

• Used in Spring Boot to extract values from the URI path.
• Works with RESTful endpoints.

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

    @GetMapping("/users/{id}")
    public String getUserById(@PathVariable("id") int userId) {
        return "User ID: " + userId;
    }
}

Usage:

GET http://localhost:8080/api/users/10

Response: User ID: 10

Use Case Scenario (Combining @RequestParam and @PathVariable)

Scenario: A user management system where:

1. We fetch user details by ID (@PathVariable).
2. We apply an optional filter (@RequestParam) for active/inactive users.

Example Code

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

    @GetMapping("/users/{id}")
    public String getUserById(
            @PathVariable("id") int userId,
            @RequestParam(name = "active", required = false, defaultValue = "true") boolean activeStatus) {
        return "User ID: " + userId + ", Active: " + activeStatus;
    }
}

Usage

GET http://localhost:8080/api/users/10?active=false

Response: User ID: 10, Active: false

Summary Table

Key Takeaways

• Use @RequestParam for query parameters in Spring Boot.
• Use @PathVariable for path parameters in Spring Boot.
• @QueryParam and @PathParam are JAX-RS specific and not used in Spring Boot.

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