#[AsBlockBinding]

Registers a block bindings source: a value computed at render time and bound to a block attribute.

TIP

A value that is merely stored needs none of this. A key declared with #[AsPostMeta] is bindable through core's own core/post-meta with no source of your own. See the guide.

Signature

<?php

namespace Studiometa\Foehn\Attributes;

use Attribute;

#[Attribute(Attribute::TARGET_CLASS)]
final readonly class AsBlockBinding
{
    public function __construct(
        public string $name,
        public string $label,
        public array $usesContext = [],
    ) {}
}

Parameters

Parameter	Type	Default	Description
name	string	required	namespace/name. A name without the slash is refused at discovery
label	string	required	Shown in the editor's binding UI
usesContext	list<string>	[]	Block context keys the value needs, e.g. postId

BlockBindingInterface

<?php

namespace Studiometa\Foehn\Contracts;

use WP_Block;

interface BlockBindingInterface
{
    public function value(array $args, WP_Block $block, string $attribute): ?string;
}

Required. A class carrying the attribute without it is refused during discovery.

Parameter	Contents
$args	What the binding declared in the block's markup, e.g. ['key' => 'price']
$block	The block being rendered; its context holds the keys usesContext asked for
$attribute	Which attribute is being bound — a source on two attributes is called twice

Returning null leaves the attribute as the block author wrote it.

Usage

#[AsBlockBinding(name: 'theme/reading-time', label: 'Reading time', usesContext: ['postId'])]
final readonly class ReadingTime implements BlockBindingInterface
{
    public function value(array $args, WP_Block $block, string $attribute): ?string
    {
        // …
    }
}

Notes

• Registered on init, which is where register_block_bindings_source() belongs.
• The class is resolved when a bound block renders, not when the source is registered, so a source nothing binds to costs nothing.
• Which attributes accept a binding is version-dependent. See the guide for the WordPress 7.0 list and the filter that extends it.
• A WordPress older than 6.5 gets no sources rather than a fatal error.

Related

• Guide: Block Bindings
• #[AsPostMeta]
• #[AsBlock]