WP_View_Config_Data::merge( array $patch, int $version ): WP_View_Config_Data

Applies a patch of top-level keys and touches only the keys the patch names: a key the patch omits keeps whatever it had, and a null value drops the key it names (which resets it to its default). Each named key's value is then merged into the current one by value shape:

• a scalar replaces the current value;
• an associative array merges key by key, with a nested null deleting just the leaf it names;
• a list merges into the current list by member identity.

Identity is the member's value cast to a string: a bare scalar is its own identity, and a map is identified by the value of the first of the well-known identity keys (id, slug, field) it carries. A member whose identity matches one already present merges into it in place, keeping its position; a member with no identity is appended to the end of the list.

For example, given this patch:

array(
 'default_view' => array( 'titleField' => 'newTitleField', 'fields' => array( 'newField' ) ),
 'default_layouts' => array( 'grid' => array( 'layout' => array( 'badgeFields' => array( 'newField' ) ) ) ),
 'view_list' => array( array( 'slug' => 'table', 'title' => 'New title' ) ),
)

• default_view will be updated so the titleField is 'newTitleField' and the newField is appended to the list of fields.
• default_layouts will be updated so that newField is appended to the badgeFields.
• view_list will be updated so that the view with slug 'table' has its title changed to 'New title'.

A patch value only merges into a current value of the same shape: an associative array where a list lives, or a non-empty list where an associative value lives, is rejected with a notice and leaves the current value unchanged. An empty array merges nothing and is a no-op — clear a list with replace() and an empty list, or reset a key to its default with a top-level null.

A patch that declares an unsupported schema version is rejected and does not change anything.