How to use render_block filter in WordPress

This filter is used to filter the content of a single block. It’s a very useful filter to modify the content of a block before displaying it on the page. For example, if you want to add a div wrapper on a ‘core/paragraph’ type of block, then you can use this filter.

To use the render_block filter, first, you have to register it using add_filter. You can write this code into functions.php of your activated theme or in a custom WordPress Plugin.

We at WePlugins always prefer to create a custom WordPress Plugin while using hooks so nothing breaks when you update your WordPress Theme in the future.

Parameters

Below are the 3 parameters required to use this hook.

• $block_content : (string) The block content is about to be appended.
• $block : (array) The full block, including name and attributes.
• $instance : (WP_Block) The block instance.

Live Example 1: Wrapping Core Paragraph Blocks

In this live example, I’ve added a stylish touch by wrapping all ‘core/paragraph’ blocks with a red background and white font color using a div. Check out the source code below!

	function weplugins_modify_render_block_defaults($block_content, $block, $instance) {
		if($block['blockName'] == 'core/paragraph') {
			return "<div style='background:red; color:white;padding:10px;'>".$block_content."</div>";
		} else {
			return $block_content;
		}
	}
	// add the filter
	add_filter("render_block", "weplugins_modify_render_block_defaults", 10, 3);
	

Live Example 2: Generic Example

Below is a generic example of how you can use this hook.

	function weplugins_modify_render_block_defaults($block_content, $block, $instance) { 
		// Update the $block_content variable according to your website requirements and return this variable. You can modify the $block_content variable conditionally too if you want.
		return $block_content; 
	}
	// add the filter
	add_filter("render_block", "weplugins_modify_render_block_defaults", 10, 3);
	

Live Example 3: Removing a Hook Callback

To remove a hook callback, use the example below.

	remove_filter("render_block", "weplugins_modify_render_block_defaults", 10, 3);
	

Please make sure to provide the same callback function name, priority, and number of arguments while removing the hook callback.

Contact Us

If you’re having any trouble using this hook, please contact our WordPress Development Team and we’d be happy to assist you.