wordpress添加文章固定字段

让wordpress的文章数据表 增加一个字段，使其能在文章编辑页能编辑，并能通过rest api 获取出来。

例：给文章加一个缩略图字段 litpic

首先 通过mysql 给文章表 wp_posts 加一个字段 litpic

然后在主题的function.php 后面添加如下代码：

add_action( ‘add_meta_boxes‘, ‘myplugin_add_custom_box‘);

add_action( ‘save_post‘, ‘myplugin_save_postdata‘);

function myplugin_add_custom_box() {
add_meta_box(
‘myplugin_sectionid‘,
‘设置缩略图‘, // 可自行修改标题文字
‘myplugin_inner_custom_box‘,
‘post‘
);
}

function myplugin_inner_custom_box( $post ) {
global $wpdb;

// Use nonce for verification
wp_nonce_field( plugin_basename( __FILE__ ), ‘myplugin_noncename‘ );

// 获取固定字段litpic的值，用于显示之前保存的值
// 此处wp_posts新添加的字段为litpic，多个用半角逗号隔开
$date = $wpdb->get_row( $wpdb->prepare( "SELECT litpic FROM $wpdb->posts WHERE ID = %d", $post->ID) );

// litpic  字段输入框的HTML代码
echo ‘<label for="litpic_new_field">图片url </label>‘;
echo ‘<input type="text" id="litpic_new_field" name="litpic_new_field" value="‘.$date->litpic.‘" size="28" />‘;
// 多个字段依此类推
}

function myplugin_save_postdata( $post_id ) {
// verify if this is an auto save routine.
// If it is our form has not been submitted, so we dont want to do anything
if ( defined( ’DOING_AUTOSAVE’ ) && DOING_AUTOSAVE )
return;

// verify this came from the our screen and with proper authorization,
// because save_post can be triggered at other times
if ( !wp_verify_nonce( $_POST[‘myplugin_noncename‘], plugin_basename( __FILE__ ) ) )
return;

// 权限验证
if ( ‘post‘ == $_POST[‘post_type‘] ) {
if ( !current_user_can( ‘edit_post‘, $post_id ) )
return;
}

// 获取编写文章时填写的固定字段的值，多个字段依此类推
$litpic = $_POST[‘litpic_new_field‘];

global $wpdb;
$wpdb->update( "$wpdb->posts",
// 以下一行代码，多个字段的话参照下面的写法，单引号中是字段名，右边是变量值。半角逗号隔开
array( ‘litpic‘ => $litpic),
array( ‘ID‘ => $post_id ),
// 添加了多少个新字段就写多少个%s，半角逗号隔开
array( ‘%s‘),
array( ‘%d‘)
);
}

添加后，文章页会显示litpic字段的输入框，如图：

但此时 rest api还不会把litpic字段输出。

打开 /wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php 文件。

添加如下代码：

if ( ! empty( $schema[‘properties‘][‘litpic‘] ) ) {
            $data[‘litpic‘] = $post->litpic;
        }

‘litpic‘        => array(
                    ‘description‘ => __( ‘A litpic to protect access to the content and excerpt.‘ ),
                    ‘type‘        => ‘string‘,
                    ‘context‘     => array( ‘view‘, ‘edit‘, ‘embed‘ ),
                ),

$post_type_attributes = array(
            ‘title‘,
            ‘editor‘,
            ‘author‘,
            ‘excerpt‘,
            ‘thumbnail‘,
            ‘comments‘,
            ‘revisions‘,
            ‘page-attributes‘,
            ‘post-formats‘,
            ‘custom-fields‘,
            ‘litpic‘,
        );
        $fixed_schemas = array(
            ‘post‘ => array(
                ‘title‘,
                ‘editor‘,
                ‘author‘,
                ‘excerpt‘,
                ‘thumbnail‘,
                ‘comments‘,
                ‘revisions‘,
                ‘post-formats‘,
                ‘custom-fields‘,
                ‘litpic‘,
            ),

case ‘litpic‘:
                    $schema[‘properties‘][‘litpic‘] = array(
                        ‘description‘ => __( ‘The ID for the litpic of the object.‘ ),
                        ‘type‘        => ‘string‘,
                        ‘context‘     => array( ‘view‘, ‘edit‘, ‘embed‘ ),
                    );
                    break;

现在，rest api 就可以把litpic 字段输出了。

原文地址：https://www.cnblogs.com/lijea/p/9252222.html