<h1>Understanding API Parameters in Spring Boot</h1>

When designing APIs in Spring Boot, it's essential to understand how to handle different types of parameters. These parameters define how data is sent from the client to the server. Let's break down the common types of parameters used in API development, with examples and cURL commands.

1. Types of Parameters

Parameter Type	Location	Use Case	Example Format	Annotation in Spring Boot
Query Param	URL after `?`	Filtering, Pagination	?key=value	@RequestParam
Path Param	In the URL path	Identifying specific resource	/resource/{id}	@PathVariable
Form Param	Form-encoded body	Simple form submissions	key=value	@RequestParam
Request Body	JSON or raw data in body	Complex objects or large payloads	JSON or XML	@RequestBody

2. Examples

1. Query Parameters

@GetMapping("/api/products")
public ResponseEntity<List<Product>> getProducts(@RequestParam String category) {
    return ResponseEntity.ok(productService.getProducts(category));
}
    

cURL:

curl -X GET "http://localhost:8080/api/products?category=electronics"

2. Path Parameters

@GetMapping("/api/products/{id}")
public ResponseEntity<Product> getProductById(@PathVariable Long id) {
    return ResponseEntity.ok(productService.getProductById(id));
}
    

cURL:

curl -X GET "http://localhost:8080/api/products/123"

3. Form Parameters

@PostMapping("/api/products")
public ResponseEntity<Product> createProduct(@RequestParam String name, @RequestParam double price) {
    return ResponseEntity.ok(productService.createProduct(name, price));
}
    

cURL:

curl -X POST "http://localhost:8080/api/products" -d "name=phone&price=50000"

4. Request Body (JSON)

@PostMapping("/api/products")
public ResponseEntity<Product> createProduct(@RequestBody Product product) {
    return ResponseEntity.ok(productService.createProduct(product));
}
    

cURL:

curl -X POST "http://localhost:8080/api/products" -H "Content-Type: application/json" -d '{"name":"phone","price":50000}'

Conclusion

Understanding how to handle query, path, form, and body parameters is essential for building robust APIs in Spring Boot. By selecting the right parameter type for the right scenario, you can create efficient, scalable, and well-structured applications.

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