我正在尝试对wp Post Meta表进行wp查询，在那里我想检查Post的Meta键及其Meta值是否为空。

元键是wc_pay_per_post_product_ids。

IF 如果语句为TRUE，则显示以下内容：

<h1>The Meta Key Is Empty or NULL</h1>
<div class="row"><div class="col-2">One</div><div class="col-10">Two</div></div>

ELSE:

<h1>The Meta Key Is NOT Empty or NULL</h1>
<div class="row"><div class="col-4"></div><div class="col-4"></div><div class="col-4"></div></div>

这是完整的代码。

<?php
  global $wpdb;
  $post_id = get_the_ID();
  $meta_value = \'wc_pay_per_post_product_ids\';

    $args = array(
        \'post_type\' => \'post\',
        \'meta_query\'     => array(
        array(
            \'post_id\' => get_the_ID(),
            \'key\'     => \'wc_pay_per_post_product_ids\',
            \'compare\' => \'EXIST\' // CHECK THE VALUE OF META KEY IF EXISTS?
        ) 
        )
    );

    if ($arg == TRUE) {
        echo \'<h1>The Meta Key Is Empty or NULL</h1><div class="row"><div class="col-2"></div><div class="col-10"></div></div>\';
    } else {
        echo \'<h1>The Meta Key Is NOT Empty or NULL</h1><div class="row"><div class="col-4">ONE</div><div class="col-4">TWO</div><div class="col-4">THREE</div></div>\';
    }

?>

以下是我的表格截图：

我遇到的问题是它总是返回结果；元密钥不为空或NULL“

$args = array(
    \'post_type\' => \'post\',
);

// Get all matching posts, with and without the meta wc_pay_per_post_product_ids.
$query = new WP_Query( $args );

while ( $query->have_posts() ) : $query->the_post();
    // Get the meta value.
    $meta = get_post_meta( get_the_ID(), \'wc_pay_per_post_product_ids\', true );

    // Then do an if-else:
    if ( $meta ) {
        echo \'has meta<br>\';
    } else {
        echo \'has no meta<br>\';
    }
endwhile;

if ( metadata_exists( \'post\', get_the_ID(), \'wc_pay_per_post_product_ids\' ) ) {
    echo \'has meta<br>\';
} else {
    echo \'has no meta<br>\';
}