register_block_bindings_source( string $source_name, array $source_properties ): WP_Block_Bindings_Source|false

Description

Registering a source consists of defining a name for that source and a callback function specifying how to get a value from that source and pass it to a block attribute.

Once a source is registered, any block that supports the Block Bindings API can use a value from that source by setting its metadata.bindings attribute to a value that refers to the source.

Note that register_block_bindings_source() should be called from a handler attached to the init hook.

Example

Registering a source

First, you need to define a function that will be used to get the value from the source.

function my_plugin_get_custom_source_value( array $source_args, $block_instance, string $attribute_name ) {
  // Your custom logic to get the value from the source.
  // For example, you can use the `$source_args` to look up a value in a custom table or get it from an external API.
  $value = $source_args['key'];

  return "The value passed to the block is: $value"
}

The $source_args will contain the arguments passed to the source in the block’s metadata.bindings attribute. See the example in the "Usage in a block" section below.

function my_plugin_register_block_bindings_sources() {
  register_block_bindings_source( 'my-plugin/my-custom-source', array(
    'label'              => __( 'My Custom Source', 'my-plugin' ),
    'get_value_callback' => 'my_plugin_get_custom_source_value',
  ) );
}
add_action( 'init', 'my_plugin_register_block_bindings_sources' );

Usage in a block

In a block’s metadata.bindings attribute, you can specify the source and its arguments. Such a block will use the source to override the block attribute’s value. For example:

<!-- wp:paragraph {
  "metadata": {
    "bindings": {
      "content": {
        "source": "my-plugin/my-custom-source",
        "args": {
          "key": "you can pass any custom arguments here"
        }
      }
    }
  }
} -->
<p>Fallback text that gets replaced.</p>
<!-- /wp:paragraph -->