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.

Pete Nelson

Allows tweaking of several REST API settings
<ul>
<li>Disable the REST API</li>
<li>Remove WordPress core endpoints</li>
<li>Require authentication for core endpoints</li>
<li>Force SSL</li>
<li>WP-CLI commands: wp rest-api-toolbox</li>
</ul>
Find us on GitHub at https://github.com/petenelson/wp-rest-api-toolbox
(Creative commons toolbox image provided by James Tworow https://www.flickr.com/photos/sherlock77/)

REST API Toolbox

Allows tweaking of several REST API settings

REST API Comment vs REST API Toolbox