在WordPress的自定义元框中添加帖子类别

Question

我想在下拉选择框中加载我的帖子类别 我该怎么做 请帮助我，我是编程新手。

这是我的代码，用于创建自定义元框，现在在类别框enter image description here中，我希望它在下拉菜单中加载所有帖子类别：代码输出显示在所附图片

<?php

//Start: Adding custom metaboxes

class leaderboarddetailMetabox {
    private $screen = array(
        'ld-leaderboard',
    );
    private $meta_fields = array(
        array(
            'label' => 'Number of Students',
            'id' => 'numberofstudent_81418',
            'type' => 'number',
        ),
        array(
            'label' => 'Select Point Type',
            'id' => 'selectpointtype_39141',
            'type' => 'select',
            'options' => array(
                'Select',
                'Int',
                'Float',
                'String',
            ),
        ),
        array(
            'label' => 'Category',
            'id' => 'category_59112',
            'type' => 'select',
            'options' => array(
                'Select',
                'Course',
                'Lesson',
                'Topic',
                'Quiz',
                'Category',
            ),
        ),
        array(
            'label' => 'Time',
            'id' => 'time_93126',
            'type' => 'date',
        ),
        array(
            'label' => 'Shortcode',
            'id' => 'shortcode_85946',
            'type' => 'text',
            'readonly' => true,
        ),
    );
    public function __construct() {
        add_action( 'add_meta_boxes', array( $this, 'add_meta_boxes' ) );
        add_action( 'save_post', array( $this, 'save_fields' ) );
    }
    // show meta boxes on admin page
    public function add_meta_boxes() {
        foreach ( $this->screen as $single_screen ) {
            add_meta_box(
                'leaderboarddetail',
                __( 'leader board detail', 'textdomain' ),
                array( $this, 'meta_box_callback' ),
                $single_screen,
                'advanced',
                'default'
            );
        }
    }
    public function meta_box_callback( $post ) {
        wp_nonce_field( 'leaderboarddetail_data', 'leaderboarddetail_nonce' );
        $this->field_generator( $post );
    }
    public function field_generator( $post ) {
        $output = '';
        foreach ( $this->meta_fields as $meta_field ) {
            $label = '<label for="' . $meta_field['id'] . '">' . $meta_field['label'] . '</label>';
            $meta_value = get_post_meta( $post->ID, $meta_field['id'], true );
            if ( empty( $meta_value ) ) {
                $meta_value = $meta_field['default']; }
            switch ( $meta_field['type'] ) {
                case 'select':
                    $input = sprintf(
                        '<select id="%s" name="%s">',
                        $meta_field['id'],
                        $meta_field['id']
                    );
                    foreach ( $meta_field['options'] as $key => $value ) {
                        $meta_field_value = !is_numeric( $key ) ? $key : $value;
                        $input .= sprintf(
                            '<option %s value="%s">%s</option>',
                            $meta_value === $meta_field_value ? 'selected' : '',
                            $meta_field_value,
                            $value
                        );
                    }
                    $input .= '</select>';
                    break;
                default:
                    $input = sprintf(
                        '<input %s id="%s" name="%s" type="%s" value="%s" %s >',
                        $meta_field['type'] !== 'color' ? 'style="width: 100%"' : '',
                        $meta_field['id'],
                        $meta_field['id'],
                        $meta_field['type'],
                        $meta_value,
                        $meta_field['readonly'] ? "readonly" : ""
                    );
            }
            $output .= $this->format_rows( $label, $input );
        }
        echo '<table class="form-table"><tbody>' . $output . '</tbody></table>';
    }
    public function format_rows( $label, $input ) {
        return '<tr><th>'.$label.'</th><td>'.$input.'</td></tr>';
    }

    // save custom field data to databse and in the field 

    public function save_fields( $post_id ) {
        if ( ! isset( $_POST['leaderboarddetail_nonce'] ) )
            return $post_id;
        $nonce = $_POST['leaderboarddetail_nonce'];
        if ( !wp_verify_nonce( $nonce, 'leaderboarddetail_data' ) )
            return $post_id;
        if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE )
            return $post_id;
        foreach ( $this->meta_fields as $meta_field ) {
            if ( isset( $_POST[ $meta_field['id'] ] ) ) {
                switch ( $meta_field['type'] ) {
                    case 'email':
                        $_POST[ $meta_field['id'] ] = sanitize_email( $_POST[ $meta_field['id'] ] );
                        break;
                    case 'text':
                        $_POST[ $meta_field['id'] ] = sanitize_text_field( $_POST[ $meta_field['id'] ] );
                        break;
                }
                update_post_meta( $post_id, $meta_field['id'], $_POST[ $meta_field['id'] ] );
            } else if ( $meta_field['type'] === 'checkbox' ) {
                update_post_meta( $post_id, $meta_field['id'], '0' );
            }
            
            // generate shortcode and save
            if( $meta_field['id'] == 'shortcode_85946' ) {
                // update meta
                update_post_meta( $post_id, $meta_field['id'], "[custom-shortcode id=" . $post_id . "]");
            }
        }
    }
}
if (class_exists('leaderboarddetailMetabox')) {
    new leaderboarddetailMetabox;
};
?>