POST return "no route found" error while GET request is functional

/**
 * Provides a Demo Resource
 *
 * @RestResource(
 *   id = "my_resource",
 *   label = @Translation("My Resource"),
 *   uri_paths = {
 *     "canonical" = "/api/my_ressource",
 *     "https://www.drupal.org/link-relations/create" = "/api/my_ressource/create"
 *   }
 * )
 */
class MyResource extends ResourceBase
{

  public function get() {
    $response = ['message' => 'Hello, this is a GET response!'];
    return  new ResourceResponse($response);
  }
  
   /**
   * @return \Drupal\rest\ResourceResponse
   *   The HTTP response objects
   */
  public function post() {

    $response = ['message' => 'Hello, this is a POST response!'];
    return  new ResourceResponse($response);
  }
}

I am facing same issue:

"message": "No route found for "POST /api/demo_resource": Method Not Allowed (Allow: GET, HEAD)"

I hate to say it, but for me it ended up being something really simple. Back story... I created a custom Entity called Incident, and enabled the default REST resources that come with it (POST, GET, PATCH, DELETE). Which provides paths like /incident/1?_format=json, etc.

I then created a custom resource with GET and POST for a url of /incident/list, doing a GET worked fine on this, but doing the POST always ended up with the "no route found" error. Once I switch the canonical and link-relations paths to /list/incident, it worked immediately. So it looks like my first /incident/list path is/was somehow perhaps colliding with the POST /incident resource alongside the entity resource, instead of routing to my custom resource.

Hi!

For those of you who care, I had the same problem after upgrading to Drupal 9, POST method for my REST resources didn't work anymore (404 error) when it still worked with Drupal 8.9.

I managed to fix the problem by replacing this line in the annotations of the resources :

"https://www.drupal.org/link-relations/create" = "/my_api/create_entity"

by this one :

"create" = "/my_api/create_entity"

Hope that this will help someone!

I can confirm this fix is working as well. My full code example follows:

<?php

namespace Drupal\applesauce_endpoint\Plugin\rest\resource;

use Drupal\rest\Plugin\ResourceBase;
use Drupal\rest\ResourceResponse;
use Psr\Log\LoggerInterface;
use Symfony\Component\HttpFoundation\Request;
use Drupal\Core\Session\AccountProxyInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;


/**
 * Provides a resource to get view modes by entity and bundle.
 * @RestResource(
 *   id = "pumpkin_user_first_sign_on",
 *   label = @Translation("pumpkin User First Sign On"),
 *   uri_paths = {
 *     "canonical" = "/pumpkin-rest/user-first-signon",
 *     "create" = "/pumpkin-rest/user-first-signon"
 *   }
 * )
 */


 

 class pumpkinRestResource extends ResourceBase {
    
    protected $loggedUser;
    /**
     * Constructs a Drupal\rest\Plugin\ResourceBase object.
     *
     * @param array $config
     *   A configuration array which contains the information about the plugin instance.
     * @param string $module_id
     *   The module_id for the plugin instance.
     * @param mixed $module_definition
     *   The plugin implementation definition.
     * @param array $serializer_formats
     *   The available serialization formats.
     * @param \Psr\Log\LoggerInterface $logger
     *   A logger instance.
     * @param \Drupal\Core\Session\AccountProxyInterface $current_user
     *   A currently logged user instance.
     */

     public function __construct(array $config, $module_id, $module_definition, array $serializer_formats, LoggerInterface $logger,AccountProxyInterface $current_user) {
        parent::__construct($config, $module_id, $module_definition, $serializer_formats, $logger);
        $this->loggedUser = $current_user;
      }

   /**
   * {@inheritdoc}
   */

   public static function create(ContainerInterface $container, array $config, $module_id, $module_definition) {
    return new static(
      $config,
      $module_id,
      $module_definition,
      $container->getParameter('serializer.formats'),
      $container->get('logger.factory')->get('applesauce_endpoint'),
      $container->get('current_user')
    );
  }

   /**
   * Responds to GET request.
   * Returns a list of taxonomy terms.
   * @throws \Symfony\Component\HttpKernel\Exception\HttpException
   * Throws exception expected.
   */
  
  public function get() {
    // Implementing our custom REST Resource here.
    // Use currently logged user after passing authentication and validating the access of term list.
    if (!$this->loggedUser->hasPermission('access content')) {
      throw new AccessDeniedHttpException();
    }	
  //Apples vocabulary
	$vid = 'apples';
	$terms =\Drupal::entityTypeManager()->getStorage('taxonomy_term')->loadTree($vid);
	foreach ($terms as $term) {
	  $term_result[] = array(
	    'id' => $term->tid,
		'name' => $term->name
	  );
	}

    $response = new ResourceResponse($term_result);
    //Uncomment if desired to cache
    //$response->addCacheableDependency($term_result);
    return $response;
  }
  

    /**
   * @return \Drupal\rest\ResourceResponse
   *   The HTTP response objects
   */
    public function post(Request $request) {
      //Set second param of TRUE to have data returned as array as opposed to stdclass object
       $data = json_decode($request->getContent(), TRUE);
       //Dump data to watchdog for testing
       \Drupal::logger("pumpkinrest")->debug("Got a request:<pre>". print_r($data, true) ."</pre>");
       return  new ResourceResponse($data);
      }
    


    //End parent class
 }

Hello,

This is my code:

 * Represents Custom API records as resources.
 *
 * @RestResource (
 *   id = "custom_api",
 *   label = @Translation("Custom API"),
 *   uri_paths = {
 *     "canonical" = "/api/custom-api/{id}",
 *     "create" = "/api/custom-api"
 *   }
 * )

and still I am getting 404 in postman while hitting this url using GET method: https://mtn-drupal.ddev.site:8443/api/custom-api/22?_format=json. Permission is given also.