MB Blocks supports creating any block you desire without touching any JavaScript code, which might be problematic with PHP developers.

In addition to registering blocks with PHP or visually with Meta Box Builder, you can also register blocks using a block.json file. This new feature is compatible with the latest version of the API from WordPress, as well as provides a new method to create blocks for developers.

Since the MB Blocks version 1.5.0 was released today, the block.json feature is available for not only the newly created blocks, but also the old ones that you created previously.

Let's take a look!

This is a block that I created from a block.json metadata file. I'll use it as the demo for this article.

A custom block created by MB Blocks using the block.json file

Why block.json?

Previously, WordPress only allowed you to register blocks through JavaScript and PHP. However, these methods prevent sharing block information between the client and server.

Because the block information is not saved in the WordPress database, it leads to a series of consequences such as:

  • Couldn’t get the block data from PHP;
  • Couldn’t retrieve block data via REST API or mobile app;
  • All file assets, scripts, and styles for blocks (registered by JavaScript) will be enqueued and rendered on the frontend page all the time. The performance will be bad;
  • Couldn’t show the blocks and their information about the plugin/theme on wordpress.org.

That is the reason why WordPress 5.8 recommends developers using the block.json metadata file as the canonical way to register block types with both PHP (server-side) and JavaScript (client-side).

In essence, using a block.json file helps JavaScript and PHP both read the same data. So that WordPress can get the block information more easily and exactly. You can see the process as follows:

Process of registering block using PHP and block.json file
Source: WordPress Developer Resources
Process of registering block using JavaScript and block.json file
Source: WordPress Developer Resources

Therefore, the JSON file can resolve all of the disadvantages of the old method as I mentioned before. You can read the details of the benefits here.

You may have noticed that the block.json metadata file is a breakthrough solution for creating the custom Gutenberg block.

Note: The block.json file only describes the block's information. Developers still need to register the block through PHP and JavaScript as usual.

Create Custom Blocks Using block.json File

Before the update, MB Blocks uses a PHP array to register a block. It works pretty well and easily for many WordPress/PHP developers.

However, we can’t deny that the block.json file is a powerful solution from WordPress. So, our team decided to update the MB Blocks to support registering blocks using a block.json file. It respects WordPress standards so the registration steps are exactly the same as native WordPress block registration.

As you know, MB Blocks provides two methods so far to create the blocks:

  • Using UI provided by Meta Box Builder
  • Using PHP code

Whenever you want to create a block, whether you want to use the block.json file or not, you still should follow one of these two methods. However, there will be some differences when you use the block.json file as follows:

Method 1: Create Blocks Using the UI from Meta Box Builder

No matter if you want to create a block with or without the block.json file, the process still is going to create a field group for the blocks as usual and set it as a block in the settings.

Create custom fields as usual

You can even set how to render and style the block on the UI normally.

Render and style the block on the UI as previously

However, there is a new section in the Settings tab of the field group now, named Block JSON Settings. It allows you to register and create a block.jsonfile based on the created fields automatically.

The Block JSON Settings allows you to register the block using block.json file

If you want to register the block using the block.json file to have all the benefits of this metadata file, just turn on this button. Then, another option will appear allowing you to set the location of the .json file.

Enable the button to generate

At the same time, a block.json file will be generated automatically in your specified folder.

The generated block.json file is ready

When you open the block.json file, you can see that all the block information is included in the file as follows:

The block.json file includes block information

Note that the plugin also registers all the fields as attributes and puts them in the block.json file. This will synchronize the definition of the block in both the block.json and the Meta Box Builder.


  1. The block.json option is available since the MB Blocks version 1.5.0. This option is turned on as default for both the new register blocks and the old ones.  As well as, it works well with the old ones that were created with MB Blocks before the update without any further action.
  2. Whenever you update the block information in the Meta Box Builder (like adding more fields, changing the block settings), Meta Box will automatically re-generate the .json file then it will include the up-to-date information.

Method 2: Create Blocks Using Code

There are some small differences between creating blocks with or without the .json file. If you use the block.json file, you'll need to:

  • Create the block.json file;
  • Define the paths and the files of the rendering template as well as styles and scripts in the block.json file instead of in the PHP array.

Let’s look at more details.

Step 1: Register Fields for the Block

Previously, when you create a block with PHP, you needed to declare all of the block information, including the general information about the block, path of render and style files, and custom fields, etc. like this:

If you not use .json file, the .php file will include the general information about the block, path of render and style files, and custom fields

When you want to register this block with a block.json file, the code in this PHP file should be changed a bit.

The first part about the block’s general information, including the render and style is just optional to include to the PHP file. They will be in the block.json file and are compulsory, so there is no need to be in the PHP anymore.

Also in PHP, we should add an action to register the block.json file.

Use register_block_type() function to register the block using JSON file

It means we will register the block with the block.json metadata file located at the /blocks/quote folder. And the PHP code now contains only the list of fields for the block.

Step 2: Create the JSON File

This is a new and obligatory step. The metadata file will define the block's attributes, settings, the render file, etc. which is self-explanatory and follows the WordPress documentation.

I will create the file in the folder we registered in Step 1. In the root of your theme, create a folder for the blocks.

Then, in that folder, create a new file named quote/block.json with the following code:

Create the JSON file to declare block information and fields

In there:

  • The first part is to declare the block general information such as title, description, icon, etc. (Note: name is always written in the form meta-box/your-block-id)
  • The second part is to declare the attributes to get data from the custom fields that we added to the block as we register in the 1st step.

Step 3: Render the Block

Without using the .json file, we used to use the render_callback or render_template filter in the PHP file, like this:

Previously, you need to define the render file in function.php file

However, as I mentioned before, this part will be in the .json file if you use this file, and it will be in this syntax:

"render": "file:./quote.php"

Define the path of the render file

Then, create a new file and add some code to render the block. Basically, it is the file you used to render before.

This is an example of the render file.

Create a file to render the block

As you can see, we can use the $attributes variable instead of using the rwmb_meta() function as previously to get the fields’ data.

There is a notable point that the $attributes now includes all the data saved in custom fields.

For instance, you can use $attributes['image']['full_url'] to get all of the data of the image saved in the Single Image field from a block, instead of using the mb_get_block_field(), mb_the_block_field(), rwmb_meta(), wp_get_attachment_image() functions as previously. MB Blocks will automatically get the related image object and prepare for you to use in the template file.

It might be more convenient.

Now, go to the post editor, then you can find out your block.

The block is ready in the post editor

Settings of the block

The preview is displayed immediately when you input data since you have the render file.

The preview when input data

Step 4: Style the Block

Also similar to the rendering step, the path of the style file should be in the block.json file, instead of function.php as before.

Define the path of the file to style the block

Obviously, we’ll create that file to customize the block's appearance using the block's settings, such as alignment, color, etc.

The file to style the block

I uploaded all of these codes on Github, so you can refer to it for more details.

After registering the CSS file for the block in the .json file, the block will have a new look.

The new look of the block after styling

Last Words

For more advantages as WordPress’s recommendations, we hope that you can take all of the power from the block.json metadata file.

For daily use, we think that there is no significant difference if you use Meta Box Builder. In the case that you prefer using PHP code, there are just a few changes. We believe that MB Blocks will be one of the most optimal options for creating your own custom block without switching screens and complicated code. Don't forget to check out the updated docs as well.

So now, enjoy these features. We will gladly assist with any of your questions and problems. Thanks for reading.

2 thoughts on “MB Blocks Update: Register Block Using block.json File

  1. I'm glad to see this block.json finally getting supported. I wish there was more priority being placed on MB Blocks. ACF Blocks had this feature 2 years ago.

    In a Site Editor future, MB Blocks will make MetaBox.io more relevant and useful.

    1. Yes, according to the Plan of Meta Box 2024, MB Blocks is one of the plugins that Meta Box focuses on improving this year with expectable features.

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