Add rest field

[gin0115]

When registering meta data, if the rest schema is defined a matching rest field should created using the same schema

[gin0115]

https://developer.wordpress.org/reference/functions/register_rest_field/

Will need to add options for a get and update callbacks to the Meta_Data model to handle this.

Could use update_post_meta, update_term_meta and get_post_meta, get_term_meta as fallbacks...........with the option to make them nullable by default

[gin0115]

Made changes to the follow files as a working prototype.

Meta_Data_Registrar

/**
* Registers meta data for a defined type.
*
* Will cast WP Rest Schema model to array
*
* @param \PinkCrab\Registerables\Meta_Data $meta
* @param  string $meta_type The object type ('post', 'user', 'comment', 'term')
* @param  string $sub_type The object sub-type ('post_type', 'taxonomy')
* @return bool
* @throws \Exception if fails to register meta data.
*/
protected function register_meta( Meta_Data $meta, string $meta_type, string $sub_type ): bool {
// Clone and set the post type, while enforcing it as a post meta.
$meta = clone $meta;
$meta->object_subtype( $sub_type );
$meta->meta_type( $meta_type );

  // Normalise rest schema model to array.
  $meta = $this->normalise_rest_schema( $meta );

  $result = register_meta( $meta->get_meta_type(), $meta->get_meta_key(), $meta->parse_args() );
  if ( ! $result ) {
     throw new \Exception(
        "Failed to register {$meta->get_meta_key()} (meta) for {$sub_type} of {$meta_type} type"
     );
  }

  // Maybe register rest fields.
  if ( false !== $meta->get_rest_schema() ) {
     $this->register_meta_rest( $meta );
  }

  return $result;

}

/**

• Registers a Meta Data object as defined REST field.
• @param \PinkCrab\Registerables\Meta_Data $meta

• @return void */ protected function register_meta_rest( Meta_Data $meta ) { add_action( 'rest_api_init', function () use ( $meta ) { register_rest_field( $meta->get_subtype(), $meta->get_meta_key(), array( 'get_callback' => $meta->get_rest_get() ?? $this->create_rest_get_method( $meta->get_type(), $meta->get_meta_key() ), 'schema' => $meta->get_rest_schema(), 'update_callback' => $meta->get_rest_set(), ), ); } ); }

  /**

• Creates a fallback rest get callback.
• @param string $type The meta type.
• @param string $meta_key The meta key.

• @return callable */ protected function create_rest_get_method( string $type, string $meta_key ): callable { return function( $object ) use ( $type,$meta_key ) { switch ( $type ) { case 'post': $value = get_post_meta( $object['id'], $meta_key, true ); break;

      case 'term':
         $value = get_term_meta( $object['id'], $meta_key, true );
         break;
  
      case 'user':
         $value = get_user_meta( $object['id'], $meta_key, true );
         break;
  
      case 'comment':
         $value = get_comment_meta( $object['id'], $meta_key, true );
         break;
  
      default:
         $value = null;
         break;
   }
  
   return $value;

  }; }

  
  > Still needs the UPDATE fallback being created.

FILE :: Meta_Data

/**
* The meta fields callbacks
*
* @var array{
*  sanitize: null|callable,
*  permissions: null|callable,
*  rest_get: null|callable,
*  rest_set: null|callable
* }
*/
protected $callbacks = array(
'sanitize'    => null,
'permissions' => null,
'rest_get'    => null,
'rest_set'    => null,
);

/**

• Sets the GET callback for REST requests.
• @param callable|null $callback

• @return self */ public function rest_get( ?callable $callback ): self { $this->callbacks['rest_get'] = $callback; return $this; }

  /**

• Sets the SET/UPDATE callback for REST requests.
• @param callable|null $callback

• @return self */ public function rest_set( callable $callback ): self { $this->callbacks['rest_set'] = $callback; return $this; }

  /**

• Gets the GET callback for REST requests.
• @param callable|null $callback

• @return self */ public function get_rest_get(): ?callable { return $this->callbacks['rest_get']; }

  /**

• Sets the GET callback for REST requests.
• @param callable|null $callback

• @return self */ public function get_rest_set(): ?callable { return $this->callbacks['rest_set']; }

  /**

• Get object type meta applies to

• @return string */ public function get_type(): string { return $this->meta_type; }

  /**

• Get holds a secondary object type, used for post type and taxonomy.
• @return string|null */ public function get_subtype(): ?string { return $this->object_subtype; }

Get and Update names need ammedning Update callback generator needs creating