replace_child_block_by_path

Description

The replace_child_block_by_path() method targets a child block by its path within a nested child block structure and replaces it with a new child block definition. This is particularly useful when you need to override or extend child blocks that are defined in a parent block class.

Responsibility

This method recursively searches through an array of child blocks using a path-based approach (e.g., "table/row/cell") to locate a specific child block, then replaces it with a new Child_Block instance. This allows you to modify child blocks that are defined in parent classes without having to completely redefine the entire child block hierarchy.

Arguments

Parameter	Type	Required	Description
$existing_child_blocks	Child_Block[]	Yes	An array of existing child blocks to search in
$path	string	Yes	A "/" separated path to the target block (e.g., "table/row/cell" or "table/row/cell/cell-content")
$new_child_block	Child_Block	Yes	The new child block instance to replace the existing one

Return Value

• Type: Child_Block[]
• Description: Returns the array of child blocks with the specified block replaced

Path Format

The path parameter uses a forward-slash (/) separated format to navigate through nested child blocks:

• Each segment represents a child block name
• The path is traversed from top to bottom
• Example: "table/row/cell" means:
  • Find a child block named "table"
  • Within that, find a child block named "row"
  • Within that, find a child block named "cell"
  • Replace that "cell" block with the new one

Pairing with get_child_block_by_path

This function pairs exceptionally well with get_child_block_by_path(). The recommended workflow is:

1. Use get_child_block_by_path() to retrieve the existing child block you want to modify
2. Make your modifications to the retrieved block (e.g., add fields, change configuration)
3. Use replace_child_block_by_path() to replace the original block with your modified version

This approach is much easier than manually recreating the entire Child_Block instance, especially when you only want to add a few fields or make small modifications to an existing child block.

Examples

Basic Usage - Extending a Child Block

This example shows the recommended approach for extending a child block defined in a parent class. First, retrieve the existing block using get_child_block_by_path(), modify it, and then replace it. This approach preserves all existing fields and configuration:

use Creode_Blocks\Table_Block as Base_Table_Block;
use Creode_Blocks\Helpers;

class Table extends Base_Table_Block {

	/**
	 * {@inheritdoc}
	 */
	protected function name(): string {
		return 'table';
	}

	/**
	 * {@inheritdoc}
	 */
	protected function label(): string {
		return 'Comparison Table';
	}

	/**
	 * {@inheritdoc}
	 */
	protected function child_blocks(): array {
		$existing_child_blocks = parent::child_blocks();

		// Get the existing cell-content child block
		$cell_content_child_block = Helpers::get_child_block_by_path(
			$existing_child_blocks,
			'table/row/cell/cell-content'
		);

		// Get the existing fields array and add the new field to it
		$fields = $cell_content_child_block->fields;
		$fields[] = array(
			'key'     => 'creode_field',
			'label'   => 'Creode Field',
			'name'    => 'creode_field',
			'type'    => 'select',
			'choices' => array(
				''  => 'hooray',
				'1' => 'woohoo',
				'2' => 'I did it',
			),
		);
		$cell_content_child_block->fields = $fields;

		// Replace the original block with the modified version
		$replaced_child_blocks = Helpers::replace_child_block_by_path(
			$existing_child_blocks,
			'table/row/cell/cell-content',
			$cell_content_child_block
		);

		return $replaced_child_blocks;
	}
}

Shallow Path Replacement

You can also replace child blocks at the top level of the hierarchy:

use Creode_Blocks\Helpers;
use Creode_Blocks\Child_Block;

protected function child_blocks(): array {
	$existing_child_blocks = parent::child_blocks();

	// Replace a top-level child block
	$replaced_child_blocks = Helpers::replace_child_block_by_path(
		$existing_child_blocks,
		'section',
		new Child_Block(
			'section',
			'Enhanced Section',
			array(
				// Additional fields here
			),
			__DIR__ . '/templates/enhanced-section.php'
		),
	);

	return $replaced_child_blocks;
}

Use Cases

This helper is particularly useful when:

• Extending parent block classes: You want to add fields to a child block defined in a parent class without modifying the parent
• Customizing child blocks: You need to modify the template, fields, or configuration of a nested child block
• Selective overrides: You only want to change specific child blocks in a complex hierarchy rather than redefining everything
• Working with existing blocks: When combined with get_child_block_by_path(), you can easily retrieve, modify, and replace existing child blocks without recreating them from scratch

Notes

• If the path doesn't match any existing child blocks, the original array is returned unchanged
• The path matching is case-sensitive and must exactly match the child block names
• Only the first matching child block at each level is replaced (if multiple child blocks share the same name, only the first one is affected)
• The replacement maintains the position of the original child block in the array