Spring REST Concepts: Difference between revisions

From NovaOrdis Knowledge Base
Jump to navigation Jump to search
Line 54: Line 54:
=Update a Resource=
=Update a Resource=


Update a REST resource by annotating handlers of a [[@RestController]] with [[@RequestMapping]], [[@PutMapping]] or [[@PatchMapping]]. PUT is idempotent.
Update a REST resource by annotating handlers of a [[@RestController]] with [[@RequestMapping]], [[@PutMapping]] or [[@PatchMapping]]. PUT is idempotent. Also see [[Request_Body_and_Jackson_Deserialization|Request Body and Jackson Deserialization]] above.


=Delete a Resource=
=Delete a Resource=

Revision as of 15:56, 27 March 2019

Internal

Overview

The. Spring REST concepts page is an extension of the Spring MVC Concepts page. Spring MVC concepts are used and extended to provide REST support.

Playground

@RestController Example

Annotations

Receive Data from Client

TODO: REST and Hypermedia

Via Path

Query Parameters

Path Parameters

Via Request

Request Headers

Request Body

Request Body and Jackson Deserialization

If the request body is encoded as "application/json", and it is declared as:

Spring handles it transparently, it deserializes JSON and instantiates the Java object representing the body.

Form Parameters

Read a Resource Representation

Read REST resources by annotating handlers of a @RestController with @RequestMapping and @GetMapping.

Create a Resource

Create a REST resource by annotating handlers of a @RestController with @RequestMapping, @PostMapping. POST is not safe and not idempotent.

Update a Resource

Update a REST resource by annotating handlers of a @RestController with @RequestMapping, @PutMapping or @PatchMapping. PUT is idempotent. Also see Request Body and Jackson Deserialization above.

Delete a Resource

Delete a REST resource by annotating handlers of a @RestController with @DeleteMapping.

Send a Response to Client

The @RestController annotation implies @ResponseBody, which maps the result produced by the handler method onto the body of the HTTP response.

By default, if all goes well - no exceptions are thrown - the HTTP status code is 200, even if the method returns null.

If the method handler wants to control the HTTP status code, it has the option of wrapping the response in a ResponseEntity<>, which, along the body, allows specifying the response code:

import org.springframework.http.ResponseEntity;
...
public ResponseEntity<A> get(...) {

  // if found ...
  return new ResponseEntity<>(a, HttpStatus.OK);

  // ... else
  return new ResponseEntity<>(null, HttpStatus.NOT_FOUND);
}

Another way of statically enforcing a response code is with @ResponseStatus.


It is always a good idea to send a specific response code, instead of 200, where appropriate to communicate the most descriptive and accurate HTTP status to the client.

REST Clients

RestTemplate

TO PROCESS: https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#webmvc-resttemplate

POSTing Resource. Data

This overloaded version allows you to receive the newly created resource as a domain model object:

RestTemplate restTemplate = new RestTemplate();

MyResource model = new MyResource(...);

MyResource created = restTemplate.postForObject("http://localhost:8080/myresource", model, MyResource.class);