Return entity object in REST response body after successful POST

I do support this feature! should be included in drupal 8 core

I think the location header had this info?

Only if you assume that it contains the entity type/ID and it could be different for some entity types. And you could have aliases, for example...

It is very interesting, I think in some cases we will need the entity id.

Makes sense, as far as I can see it is allowed to return a body with a 201 response. Should we just return the full newly created entity representation, the same that we would return on GET requests? That way API consumers don't need to learn a new format, they just get the same entity they already know from GET requests.

And this needs a test case, should be added to the POST create tests.

We should also update the comment in the code, which wrongly says that 201 responses are empty.

Test was updated to validate serialized UUID against response UUID, if is the same means the entity was process successfully

Removed extra line

+++ b/core/modules/rest/src/Tests/CreateTest.php
@@ -361,8 +361,13 @@ public function createAccountPerEntity($entity_type) {
+    ¶

Whitespace

1. +++ b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
   @@ -107,9 +107,9 @@ public function post(EntityInterface $entity = NULL) {
   +      // 201 Created response have the new entity created.
   

   Should be "201 Created responses return the newly created entity in the response body."

2. +++ b/core/modules/rest/src/Tests/CreateTest.php
   @@ -361,8 +361,13 @@ public function createAccountPerEntity($entity_type) {
   +    // Validate is object UUID send is the same returned
   

   Should be "Make sure that the response includes an entity in the body and check the UUID as an example."

+++ b/core/modules/rest/src/Tests/CreateTest.php
@@ -361,8 +361,13 @@ public function createAccountPerEntity($entity_type) {
+    $request = \Drupal\Component\Serialization\Json::decode($serialized);
+    $response = \Drupal\Component\Serialization\Json::decode($response);

Please move the namespaces to "use" statements.

we already have "use Drupal\Component\Serialization\Json;"
fixed php comments and used Json::decode

wrong comment number in filename, renamed

1. +++ b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
   @@ -107,9 +107,9 @@ public function post(EntityInterface $entity = NULL) {
   +      // 201 Created responses return the newly created entity in the response body.
   

   Comments should wrap at 80 characters, see https://www.drupal.org/coding-standards/docs#drupal

2. +++ b/core/modules/rest/src/Tests/CreateTest.php
   @@ -361,8 +361,13 @@ public function createAccountPerEntity($entity_type) {
   +    // Make sure that the response includes an entity in the body and check the UUID as an example.
   

   same here.

oops, fixed

1. +++ b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
   @@ -107,9 +107,10 @@ public function post(EntityInterface $entity = NULL) {
   +      // 201 Created responses return the newly created entity in the
   +      // response body.
   

   "response" still fits on the line before, let's use as much of the 80 character line length as possible.

2. +++ b/core/modules/rest/src/Tests/CreateTest.php
   @@ -361,8 +361,14 @@ public function createAccountPerEntity($entity_type) {
   +    // Make sure that the response includes an entity in the body and check
   +    // the UUID as an example.
   

   same here, the "the" still fits on the line before.

SimpleTest passed

Looks good!

This would be a huge win for the REST experience.

But probably should go in 8.1.

This needs a change record, so marking needs work for that, but otherwise looks good.

Better title too.

CR created: https://www.drupal.org/node/2665276.

Committed/pushed to 8.1.x, thanks!

YAY! This is a huge win in terms of RX and perf. Glad to see this in.