View Config: Add version handling

[ntsekouras]

Backport the GB PR: WordPress/gutenberg#79809

Trac ticket: https://core.trac.wordpress.org/ticket/65577

What?

Adds version handling to the server-side view configuration API (wp_get_entity_view_config()).

Why?

Right now consumers of the filters have to customize the config by walking the raw payload (find the right index, foreach, unset, etc.), and imperative array manipulation can never be migrated. A later shape change could break existing callbacks in the wild. So even though there is only version 1 today and no migrations exist, this code is the safeguard to keep filters working in a possible shape change.

How?

The approach here partially mirrors theme.json version handling, where documents declare a version and WP_Theme_JSON_Data->update_with() migrates older data forward. So instead of mutating a single payload directly, now callbacks receive a data container (WP_View_Config_Data) and update the config through the container's specific methods.

Any update made is marked against the version it was written, and the payload could be migrated in newer versions.

Where it differs from theme.json handling is the need for updating configs that are arrays (e.g. fields and view_list) and handling index based transforms cannot happen reliably in a filter. These props though have stable identities (field.id, view_list.slug), so each part of the config has its own update function and patches are keyed by that identity: the key names the member, the value carries only the changes. All the update functions follow the same rules — an associative array merges key by key, a numerically indexed array replaces wholesale, and null deletes what it names: a nested key, a whole member, or a whole top-level key (which resets it to its default).

update_properties()

• update_properties( $patch, $version ) merges partial changes into default_view, default_layouts, and form except its fields.
• a null patch value unsets a nested key, and null for a whole top-level key resets it to its default.

function example_filter_page_view_config( $data ) {
    // Unset a nested value with null: drop the grid layout option. Form
    // properties other than `fields` also merge here.
    $data->update_properties(
        array(
            'default_layouts' => array( 'grid' => null ),
            'form'            => array( 'layout' => array( 'type' => 'regular' ) ),
        ),
        1
    );

    return $data;
}
add_filter( 'get_entity_view_config_postType_page', 'example_filter_page_view_config' );

update_view_list_items()

• update_view_list_items( $items, $version ) patches the view_list, keyed by slug.
• a matching view merges in place, an unknown slug appends a new view to the end, and null removes the view.

function example_filter_page_view_config( $data ) {
    // Add a saved view, retitle the existing Drafts view — matched by slug,
    // only the given keys change — and remove the Trash view with null.
    $data->update_view_list_items(
        array(
            'my-drafts' => array(
                'title' => __( 'My drafts', 'example' ),
                'view'  => array(
                    'filters' => array(
                        array(
                            'field'    => 'status',
                            'operator' => 'isAny',
                            'value'    => 'draft',
                            'isLocked' => true,
                        ),
                    ),
                ),
            ),
            'drafts'    => array( 'title' => __( 'In progress', 'example' ) ),
            'trash'     => null,
        ),
        1
    );

    return $data;
}
add_filter( 'get_entity_view_config_postType_page', 'example_filter_page_view_config' );

update_form_fields()

• update_form_fields( $fields, $version ) patches the form fields, keyed by id. A field is found wherever it lives — at the top level or nested inside a group's children — so a patch only needs the id.
• a matching field merges in place, an unknown id appends a new field, and null removes the field.
• the id lives in the patch key and the value only carries overrides, so a new field with no overrides is 'my_field' => array(). Inside a field patch, an associative children value merges into the group's children by id (unknown ids append to the group), while a numerically indexed one replaces them wholesale.

function example_filter_page_view_config( $data ) {
    // Change label position of the post-content-info field, remove the slug
    // and author fields with null, and append a field to the discussion group.
    $data->update_form_fields(
        array(
            'post-content-info' => array(
                'layout' => array( 'labelPosition' => 'side' ),
            ),
            'slug'              => null,
            'author'            => null,
            'discussion'        => array(
                'children' => array( 'my_field' => array() ),
            ),
        ),
        1
    );

    return $data;
}
add_filter( 'get_entity_view_config_postType_page', 'example_filter_page_view_config' );

set()

Replaces a whole top-level key. It shouldn't be the default choice — a callback using it stops inheriting core's future changes to that key — but it's useful for cases like a CPT that doesn't want the default post form at all.

function example_filter_book_view_config( $data ) {
    // The default post form doesn't fit books; define one from scratch.
    return $data->set(
        'form',
        array(
            'layout' => array( 'type' => 'panel' ),
            'fields' => array( 'isbn', 'publisher' ),
        ),
        1
    );
}
add_filter( 'get_entity_view_config_postType_book', 'example_filter_book_view_config' );

Testing Instructions

The editor changes consuming the versioned endpoint live in the Gutenberg packages, so testing here is against the API and REST endpoint directly.

1. Start a WordPress development environment and add a callback combining the patches above, e.g. in a mu-plugin:

add_filter(
	'get_entity_view_config_postType_page',
	function ( $data ) {
		$data->update_view_list_items(
			array(
				'my-drafts' => array(
					'title' => 'My drafts',
					'view'  => array(
						'filters' => array(
							array(
								'field'    => 'status',
								'operator' => 'isAny',
								'value'    => 'draft',
								'isLocked' => true,
							),
						),
					),
				),
				'drafts'    => array( 'title' => 'In progress' ),
				'trash'     => null,
			),
			1
		);

		$data->update_form_fields(
			array(
				'slug'       => null,
				'author'     => null,
				'discussion' => array( 'children' => array( 'my_field' => array() ) ),
			),
			1
		);

		$data->update_properties(
			array( 'default_layouts' => array( 'grid' => null ) ),
			1
		);

		return $data;
	}
);

2. Log in as an admin, open the editor for any post or page (or the Site Editor), and request the config from the browser console:

wp.apiFetch( { path: '/wp/v2/view-config?kind=postType&name=page' } ).then( console.log );

3. Verify in the response:
   • version is 1.
   • view_list: the "My drafts" view is appended, the Drafts view is retitled "In progress" (its filters untouched), and the Trash view is gone.
   • form.fields: slug and author are gone, and the discussion group's children include my_field.
   • default_layouts no longer has a grid key.
4. Remove the callback and verify the response returns to the defaults.
5. Play around with different payloads.
6. CI green.

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Opus 4.8, Claude Fable 5
Used for: Porting the merged Gutenberg PR to core with direction, changes and review by me.

---

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[github-actions]

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Props ntsekouras, mcsf.

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[github-actions]

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[mcsf]

This looks pretty good! I left a couple of recommendations.

[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 62668
GitHub commit: 51a575c

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.