When creating a custom category into which you want to group your own blocks, you may also want to create a block that can only hold blocks that belong to that group. Or, in other words, you may want to create a block that can nest related blocks.

For example, in the last post, I showed how to create a custom category into which blocks can be grouped. And that works well when you can want to create a group for related blocks.

This can be taken a step further, though. Say you want to create a custom block that can only hold blocks that are part of your custom category.

---

The primarily things that need to be done to achieve this are:

1. Make sure the block you’re creating is also part of the same custom category.
2. In the supports attribute, specifically list the blocks the block in question will allow.

The edit and save functions don’t need to be particularly fancy for this unless you want to achieve something more.

First, the attributes section of your block may look something like this:

Notice here it has the standard title, icon, and category all blocks have (and the category matches what was outlined previously. Now add an allowedBlocks array to the supports attribute. This is where you can restrict the blocks that can be contained within this block.

The important thing to note is that you know the namespace and name of the blocks (these are of the format namespace/block-name and are usually was you find when calling registerBlockType.

Finally, in the edit function, add this attribute to the InnerBlocks components. From the component in the GitHub repository:

InnerBlocks exports a pair of components which can be used in block implementations to enable nested block content.

The code for edit can, out of the box, look like this:

And the save function looks like this:

Finally, once you’ve done all of this and rebuilt the assets, then the block panel within the editor should yield something that looks like this:

And that’s it.

---

As mentioned earlier, you can see edit and save are simple. It’s possible to make them as elaborate as needed, but if you’re just building a container to support your custom blocks, this is all you need.

It’s been a while since I’ve done any custom block development. In fact, the last time I called bankruptcy on any content was when I was writing about building blocks for WordPress.

A bit has changed since then, though:

• the way in which blocks are developed has improved,
• and I’ve finally gotten a little more experience.

That said, there are still things that are less familiar since I spend more of my time working predominately with PHP, WordPress-adjacent tools, and custom plugins, too.

But I think it’s worth sharing a few notes that I’ve picked up if or no other reason than I can refer back to them in the future. So for the first note in these “block notes,” here’s what has to be done if you want to register a a custom block category for any custom blocks you’re building.

---

In the screenshot below, you’ll notice under the Blocks tab, you can see categories such as Text and Media:

But if you’re working on a set of custom blocks that don’t fit into these categories or that should belong to a category of their own, this is how you set it up your plugin to accomodate.

For the sake of example, let’s create a custom categories called Acme Company.

First, leverage the block_categories_all filter.

Filters the default array of categories for block types.

In the plugin bootstrap, you can add the code like this:

Notice in the code above, we’re creating a category called Acme Category. This is what will show up in the side back of the available blocks whenever we begin registering our own blocks.

And now, across the various JavaScript files in which blocks are registered, we add the category property whenever we call registerBlockType.

Registers a block type. The recommended way is to register a block type using the metadata stored in the block.json file.

For what it’s worth, I haven’t used a block.json file (at least note yet); but I do use registerBlockType in the JavaScript source in which the block file is created. For example:

Now anytime a block is registered and includes this category, the block will appear alongside any and every block that all under the same category.

This can be useful whenever you’re trying to a build a library of related blocks, or if you’re ultimately going to be working with blocks that work with each other.

And I’ll cover this case in a future note.