---
title: "lzb/block_defaults"
description: "lzb/block_defaults changes the fallback values of block settings the block builder never saved, to set a house style for every new block at once."
url: "https://www.lazyblocks.com/docs/php-filters/lzb-block_defaults/"
lastUpdated: 2026-09-23
source: "php-filters/lzb-block_defaults.mdx"
---
# lzb/block_defaults

Changes the value a block setting falls back to when the block builder never saved one, which is how a site sets its own house style for every new block at once.

This is the earliest of the four filters that shape a block. It runs inside `get_block_defaults()`, before any meta is read, so its result is only consulted when the stored meta is an empty string. Turning on `lazyblocks_supports_anchor` here gives an anchor field to every block that has never had the setting touched, and stops affecting a block the moment somebody saves that setting in the builder.

## Attributes

| Name              | Type      | Description                                               |
| ----------------- | --------- | --------------------------------------------------------- |
| `$block_defaults` | **Array** | fallback values, keyed by the raw `lazyblocks_` meta name |

The keys are meta names, not the block data keys. `lazyblocks_slug`, `lazyblocks_icon`, `lazyblocks_description`, `lazyblocks_keywords`, `lazyblocks_category`, `lazyblocks_controls`, `lazyblocks_styles`, `lazyblocks_condition_post_types`, the `lazyblocks_code_*` group (`show_preview`, `single_output`, `output_method`, `editor_html`, `editor_callback`, `frontend_html`, `frontend_callback`), the `lazyblocks_style_*` and `lazyblocks_script_*` pair, and one `lazyblocks_supports_*` entry per block support.

Booleans are stored as the strings `'true'` and `'false'`, and `get_meta_value()` converts them afterwards. `lazyblocks_supports_align` is the exception, an array holding `wide` and `full` by default.

## Usage

```php title="PHP"
function my_lzb_block_defaults( $block_defaults ) {
  // Every block that has never had these settings saved gets an anchor
  // field and no wide alignments.
  $block_defaults['lazyblocks_supports_anchor'] = 'true';
  $block_defaults['lazyblocks_supports_align']  = array();

  return $block_defaults;
}

add_filter( 'lzb/block_defaults', 'my_lzb_block_defaults' );
```

A boolean default written as a real `true` rather than the string `'true'` never survives the round trip, because `get_meta_value()` only maps the strings. Removing a key altogether means the setting has no default at all and stays an empty string.

The assembled block list is cached in a transient, and its key counts the priorities registered on this filter. A handler at a priority nothing else uses invalidates that cache by itself. A second handler at priority 10 does not, so clear the cache or wait out [lzb/cache_expiration](https://www.lazyblocks.com/docs/php-filters/lzb-cache_expiration/) before the change shows up.

The three later stages are [lzb/block_data](https://www.lazyblocks.com/docs/php-filters/lzb-block_data/), which sees the assembled block, [lzb/prepare_block_attribute](https://www.lazyblocks.com/docs/php-filters/lzb-prepare_block_attribute/), which sees one control at a time, and [lzb/register_block_type_data](https://www.lazyblocks.com/docs/php-filters/lzb-register_block_type_data/), which sees what goes to `register_block_type()`.

## Documentation Index
> Fetch the complete documentation index at: https://www.lazyblocks.com/llms.txt
> Fetch every page in a single file at: https://www.lazyblocks.com/llms-full.txt