Creating Custom Sidebars with PluginSidebar
Creating Gutenberg sidebars and panels with fields inside of them is a brand new way of working with WordPress metadata. I am sure that the default way of creating meta boxes will stay with us for a long time as a backward compatibility, but believe me that working with the content using blocks and sidebars is a much more pleasant way than trying to configure everything in old-fashioned meta boxes.
So, what we are going to do in this tutorial?
Usually I like to show practical examples in my tutorials. And here is the one – I don’t use any SEO plugins on my projects, because I think they are too heavy and bloated with code. But if you’re familiar with SEO, you know that it is important to add unique titles and meta descriptions for your website pages. And probably you would like to hide some of them from indexing with robots meta tag.

Please also stay away from tutorials where it is recommended to work directly with WordPress REST API and use wp.apiRequest
etc. That’s not a correct way of creating Gutenberg sidebars.
Simple Fields
Allows to create easily settings pages and meta fields for posts, taxonomy terms, comments and users. Gutenberg sidebars are supported. Super-fast and minimalist plugin.
Include Meta Data When Updating Users via REST API
In my another tutorial about syncing users using WordPress REST API I received a question in comments, where I was asked about metadata. After googling for quite a bit I found out that there is no clear explanation out there about using user’s meta in REST API requests.
Compare Meta Box Plugins Performance
Even though Gutenberg (WordPress Block Editor) has become our new reality and FSE themes are also on their way, we still need meta boxes on our projects. The meta boxes aren’t necessarily classic meta boxes for posts, it could be additional settings fields for taxonomies, users, comments and even options pages. It means that we are going to need them for a very long time. Maybe even forever.
Of course the best way to create any of the mentioned above is to code by yourself. But it could be really time consuming especially if you have a lot of fields (and working on lots of projects).
That’s when metabox plugins come into play. The most popular ones are Advanced Custom Fields and Carbon Fields. Also in this article I am going to mention my own metabox plugin I developed for my needs which is Simple Fields.
The idea of this tutorial is to become more conscious to what plugins we are using to achieve our goals, because there are lots of slow WordPress websites out there, not because WordPress is slow but because sites are overloaded with tens and even hundreds heavy plugins.
Let’s look the truth in the face – of course I am going to tell you how cool my Simple Fields plugin is. But I am not going to say “use it”, because I understand clearly that sometimes its functionality is not enough, then you can probably look at Carbon Fields plugin. And even Advanced Custom Fields PRO has its own advantages though I am not a big fan of it.
Meta_Query of WP_Query
In this guide I am assuming that you already have some basic knowledge how to work with WP_Query class in WordPress. And this tutorial will be all about working with custom fields.
Either you are working with Gutenberg or with Classic Editor, maybe you’re using some custom fields plugins like ACF, Carbon Fields, Simple Fields (it is my plugin, highly recommend) – in all of these cases the idea of working with Meta_Query will be the same.
Custom Product Meta
In this tutorial we are going to talk about how to add custom fields to WooCommerce products. I am not going to talk about plugins here – we will work with code snippets only and all the additional fields will be added to “Product Data” metabox.
Please also keep in mind that WooCommerce allows to hide or display specific product fields depending on a product type. So for example we can show our additional product fields only for “Downloadable” or “Variable” products.
Just like that:

How to Add Meta Fields when Creating a Post with REST API
This tutorial is a small addition to my another tutorial about creating posts with REST API in WordPress, because there I didn’t mention how to work with metadata and what moments you have to keep in mind.
As a result of this tutorial we will just create a simple draft post with a couple custom fields in it.