Joaquim Domingos António

If you wish to ‘Create comments’ using REST API, without exposing Administrator credentials to the Front-End application, you are at the right place. Since WordPress 4.7, REST API was natively included in WordPress.
In order to ‘Create a comment’ , the authentication for a user with ‘Administrator’ role is required. While this is a deliberately done for security reasons, such implementation makes it very hard for Front-End applications to implement a simple ‘Post Comment’ or ‘Reply Comment’ function.
This plugin fulfils such requirement by extending the existing WordPress REST API endpoints.
Requirements:
Minimum PHP version: 7.0 
Minimum WordPress version: 5.5
Installation:
Download the plugin form wordpress marketplace install it like any other WordPress plugin. 
After the installation activate the plugin through the ‘Plugins’ menu in WordPress
Endpoint:
When this plugin is installed one new endpoint is added to the wp/v2 namespace.
 Endpoint 
 HTTP Verb 
 Permalinks
 */wp-json/wp/v2/comments/create 
 POST 
 enabled
 */?rest_route=/wp/v2/comments/create 
 POST 
 disabled
Usage:
<ol>
<li>Create a Comment</li>
</ol>
To create a comment using REST API, send a <code>POST</code> request to:
<blockquote>
<code>/wp-json/wp/v2/comments/create</code> – if permalinks is enabled on your wordpress website.
</blockquote>
Or
<blockquote>
<code>/?rest_route=/wp/v2/comments/create</code> if permalinks is not enabled on your wordpress website.
</blockquote>
With a JSON body, as shown bellow:
<pre><code>`Json
</code></pre>
{ 
 “post”: “Post ID”, 
 “author_name”: “Comment Author’s name”, 
 “author_email”: “Comment Author’s email”, 
 “content”: “Comment content” 
} 
 `
The content may also be send as an object:
<pre><code>`Json
</code></pre>
{ 
 “post”: “Post ID”, 
 “author_name”: “Comment Author’s name”, 
 “author_email”: “Comment Author’s email”, 
 “content”: { 
 “raw”:”Comment content” 
 } 
} 
 `
Set header to:
<pre><code>`
</code></pre>
content-type: application/json 
 ` 
If successful, you should receive a response with the data of the created comment:
<pre><code>`Json
</code></pre>
{ 
 “id”: “[comment id]”, 
 “status”: “[comment status]”, 
 “message”:”[server response message]” 
} 
 `
In response header the status code should be:
<pre><code>`Http
</code></pre>
HTTP 201 Created 
 `
<ol>
<li>Reply a comment</li>
</ol>
To reply a comment you just need to add the field parent for the parent comment to the JSON body
<pre><code>`Json
</code></pre>
{ 
 “post”: “Post ID”, 
 “author_name”: “Comment Author’s name”, 
 “author_email”: “Comment Author’s email”, 
 “content”: “Comment content”, 
 “parent”:”Comment parent ID” 
} 
 `
<blockquote>
Note: Ensure the parent is a comment id that belongs to the post informed in the field post. The comment parent post id must match the post id otherwise the following error will be shown:
</blockquote>
<pre><code>`Json
</code></pre>
{ 
 “code”: “rest_post_mismatch_parent_post_id”, 
 “message”: “Post ID and Parent post ID does not match”, 
 “data”: { 
 “status”: 400 
 } 
} 
 `
<h3>Contact</h3>
If there is any thing to say about the plugin fill free to <a href="mailto:sopport@appsdabanda.com" rel="nofollow ugc">contact us</a>.

REST API Comment

REST API Comment adds in the 'Comment creation' function to the Wordpress REST API.

Andr&eacute; Boekhorst

This plugin combines the two of the best WordPress plugins: <a href="https://wordpress.org/plugins/advanced-custom-fields/" title="Advanced Custom Fields" rel="ugc">Advanced Custom Fields</a> and <a href="https://wordpress.org/plugins/json-rest-api/" title="WP REST API" rel="ugc">WP REST API</a>.
This plugin is based on the work from<a href="https://github.com/PanManAms/WP-JSON-API-ACF" title="Panman on Github" rel="nofollow ugc">Panman on Github</a>. He was right when he said it would be better as plugin, but it would be even better if it would be available through the WordPress Plugin Repository.
An addition made to this plugin is that each ACF Field van be filtered throug the hook: JSON_META_ACFFIELDNAME (where ACFFIELDNAME depends on the fieldname you’ve added in the Advanced Custom Fields backend.)

WP REST API Custom Fields

The plugin is installed but nothing is in the output of API

JUst does not work

Shows Advanced Custom Field output to the WP REST API for posts, pages, taxonomies and users.

REST API Comment vs WP REST API Custom Fields