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How to use render_block_data filter in WordPress

Sandeep Kumar Mishra
Sandeep Kumar Mishra
July 12, 2022
5 minutes read

render_block_data filter

Filters the block being rendered in render_block(), before it’s processed.

To use render_block_data 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 Flipper Code, always prefer to create a custom WordPress Plugin while using hooks so nothing breaks when you update your WordPress Theme in the future.

In the below live example, we have defined a function modify_render_block_data_defaults which takes 3 parameters and we registered using add_filter. The first parameter render_block_data is name of the hook, The second parameter modify_render_block_data_defaults is name of the function which need to be called, third parameter is the priority of calling the hook if same hook is used multiple times and the last parameter is the number of arguments (if any) to be passed in the registered function.

Sometime, you have to remove a registered hook so you can use remove_filter to remove render_block_data filter.


    Below are the 3 parameters are required to use this hook.

  • $parsed_block : (array) The block being rendered.
  • $source_block : (array) An un-modified copy of $parsed_block, as it appeared in the source content.
  • $parent_block : (WP_Block|null) If this is a nested block, a reference to the parent block.

Live Example

apply_filters( 'render_block_data', array $parsed_block, array $source_block, WP_Block|null $parent_block )

Below is an example how you can use this hook.

                        function modify_render_block_data_defaults($parsed_block, $source_block, $parent_block) { 
                            // Update the $parsed_block variable according to your website requirements and return this variable. You can modify the $parsed_block variable conditionally too if you want.

                            return $parsed_block; 
                        // add the filter
                        add_filter( "render_block_data", "modify_render_block_data_defaults", 10, 3 );

To remove a hook callback, use the example below.

remove_filter( "render_block_data", "modify_render_block_data_defaults", 10, 3 );

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

Flipper Code is a Premium WordPress Plugins development company and integrating new functionalites into WordPress sites in form of custom WordPress Plugins since 2012. If you’re having any trouble using this hook, please contact our WordPress Development Team and we’d be happy to assist you.

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