Anchor tags are returning null for custom ACF blocks

[brysonchiu]

I origonally opened this ticket, wp-graphql/wpgraphql-acf#204, but Jason Bahl directed me to open one here instead.

Steps to reproduce

1. Create a ACF block type and enable anchor attribute in the block type settings under the "Supports" tab.
2. Add the block to a page and include an anchor to the block.
3. Query:

query NewQuery {
  page(id: "/[PAGE-PATH]", idType: URI) {
    editorBlocks {
      ... on [BLOCK] {
        attributes {
          anchor
        }
      }
    }
  }
}

Anchors work for core blocks, but not for ACF blocks

[EthanCPP]

In includes/Field/BlockSupports/Anchor.php::register the field is resolved by retrieving the HTML for the block and returning the ID attribute set by Wordpress. This is returning null.

Within the $block array you can access ['attrs']['anchor'] which gives us the anchor tag without the need for decomposing the block. To test this I have replaced the resolve function with:

return $block['attrs']['anchor'];

This seems to work.

As I don't like to overwrite plugin code I have defined a new field, blockAnchor in my theme's functions.php - this can be accessed the same way the standard anchor field would be.

register_graphql_field('BlockWithSupportsAnchor', 'blockAnchor', [
    'type'        => 'string',
    'description' => __('The anchor field for the block.', 'wp-graphql-content-blocks'),
    'resolve'     => static function ($block) {
        return $block['attrs']['anchor'] ?? null;
    }
]);