fields

class Custom_Meta_Box {

	public function __construct() {

		if ( is_admin() ) {
			add_action( 'load-post.php',     array( $this, 'init_metabox' ) );
			add_action( 'load-post-new.php', array( $this, 'init_metabox' ) );
		}

	}

	public function init_metabox() {

		add_action( 'add_meta_boxes',        array( $this, 'add_metabox' )         );
		add_action( 'save_post',             array( $this, 'save_metabox' ), 10, 2 );

	}

	public function add_metabox() {

		add_meta_box(
			'',
			__( 'Options', 'text_domain' ),
			array( $this, 'render_metabox' ),
			'post',
			'advanced',
			'default'
		);

	}

	public function render_metabox( $post ) {

		// Retrieve an existing value from the database.
		$custom_ = get_post_meta( $post->ID, 'custom_', true );
		$custom_ = get_post_meta( $post->ID, 'custom_', true );
		$custom_ = get_post_meta( $post->ID, 'custom_', true );

		// Set default values.
		if( empty( $custom_ ) ) $custom_ = '';
		if( empty( $custom_ ) ) $custom_ = 'Baton Rouge';
		if( empty( $custom_ ) ) $custom_ = '225-768-2050';

		// Form fields.
		echo '<table class="form-table">';

		echo '	<tr>';
		echo '		<th><label for="custom_" class="custom__label">' . __( 'Floor', 'text_domain' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="text" id="custom_" name="custom_" class="custom__field" placeholder="' . esc_attr__( 'Floor', 'text_domain' ) . '" value="' . esc_attr( $custom_ ) . '">';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="custom_" class="custom__label">' . __( 'Appointment Locations', 'text_domain' ) . '</label></th>';
		echo '		<td>';
		echo '			<textarea id="custom_" name="custom_" class="custom__field" placeholder="' . esc_attr__( '', 'text_domain' ) . '">' . $custom_ . '</textarea>';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="custom_" class="custom__label">' . __( 'Phone', 'text_domain' ) . '</label></th>';
		echo '		<td>';
		echo '			<textarea id="custom_" name="custom_" class="custom__field" placeholder="' . esc_attr__( '', 'text_domain' ) . '">' . $custom_ . '</textarea>';
		echo '		</td>';
		echo '	</tr>';

		echo '</table>';

	}

	public function save_metabox( $post_id, $post ) {

		// Sanitize user input.
		$custom_new_ = isset( $_POST[ 'custom_' ] ) ? sanitize_text_field( $_POST[ 'custom_' ] ) : '';
		$custom_new_ = isset( $_POST[ 'custom_' ] ) ? sanitize_text_field( $_POST[ 'custom_' ] ) : '';
		$custom_new_ = isset( $_POST[ 'custom_' ] ) ? sanitize_text_field( $_POST[ 'custom_' ] ) : '';

		// Update the meta field in the database.
		update_post_meta( $post_id, 'custom_', $custom_new_ );
		update_post_meta( $post_id, 'custom_', $custom_new_ );
		update_post_meta( $post_id, 'custom_', $custom_new_ );

	}

}

new Custom_Meta_Box;