@RequestParam vs @PathVariable in Spring Boot

1. Introduction

In Spring Boot, @RequestParam and @PathVariable are two annotations used for reading the values of request parameters. @RequestParam is used to extract query parameters from the query string of the HTTP request, while @PathVariable is used to extract values from the URI path.

2. Key Points

1. @RequestParam is used to access the query parameters from the URL (e.g., /api/items?name=Table).

2. @PathVariable is used to extract values from the URI path itself (e.g., /api/items/Table).

3. @RequestParam is typically optional and has a default value if not included in the request.

4. @PathVariable is usually required as part of the URI pattern.

3. Differences

@RequestParam	@PathVariable
Used to bind query parameter values (e.g., "/api?param=value").	Used to bind URI template variables (e.g., "/api/{param}").
Optional with a default value possible.	Usually required as part of the URI.
Can have multiple parameters in a single request.	Matches the pattern defined in the URI path.

4. Example

@RestController
@RequestMapping("/api/items")
public class ItemController {

    // Using @RequestParam to extract query parameter
    @GetMapping
    public String getItemByName(@RequestParam(name = "name") String name) {
        return "Item requested: " + name;
    }

    // Using @PathVariable to extract from URI path
    @GetMapping("/{name}")
    public String getItemByPath(@PathVariable("name") String name) {
        return "Item requested: " + name;
    }
}

Output:

// No direct output, since this code is part of a Spring Boot controller.

Explanation:

1. When you call /api/items?name=Table, the getItemByName method will be invoked with "Table" as the parameter value through @RequestParam.

2. When you call /api/items/Table, the getItemByPath method will be invoked with "Table" as the parameter value through @PathVariable.

5. When to use?

- Use @RequestParam when the parameter is optional, or you need to handle complex scenarios with default values or not strictly tied to a URI structure.

- Use @PathVariable for required parameters that are a natural part of the URI and when you're modeling RESTful endpoints.