问题描述

我知道我可以在 WP_Query 中使用 REGEXP，像这样：

$query = new WP_Query(array(
  'posts_per_page'    => -1,
  'post_status'       => 'publish',
  'meta_query'        => array(
    array(
      'key'     => 'custom_fields',
      'value'   => 'foo[(][0-9][)]', // with regex stuff
      'compare' => 'REGEXP',
    ),
  ),
));

但是我也需要正则表达式。喜欢这个：

$query = new WP_Query(array(
  'posts_per_page'    => -1,
  'post_status'       => 'publish',
  'meta_query'        => array(
    array(
      'key'     => 'custom_fields[(][0-9][)]', // with regex stuff
      'value'   => 'foo',
      'compare' => 'REGEXP',
    ),
  ),
));

有什么办法可以实现这个过滤器吗？或者我必须自己用自己的 SQL 查询来构建它？

最佳解决方案

这是一个实验的想法：

假设我们得到：

post A with the custom field location1 as UK – London

post B with the custom field location2 as France – Paris

post C with the custom field location3 as USA – New York

那么我们可以使用，例如：

$args = [
    'meta_query' => [
        'relation' => 'OR',
        [
            'key'          => "^location[0-9]",
            '_key_compare' => 'REGEXP',
            'value'        => 'London',
            'compare'      => 'LIKE',
        ],
        [
            'key'          => 'location%',
            '_key_compare' => 'LIKE',
            'value'        => 'Paris',
            'compare'      => 'LIKE'
        ],
        [
            'key'          => 'location3',
            'value'        => 'New York',
            'compare'      => 'LIKE'
        ]
    ]
];

我们用以下插件支持自定义_key_compare 参数：

<?php
/**
 *  Plugin Name:   Extended Meta Key Search In WP_Query
 *  Description:   Custom '_key_compare' argument as REGEXP, RLIKE or LIKE
 *  Plugin URI:    http://wordpress.stackexchange.com/a/193841/26350
 *  Plugin Author: Birgir Erlendsson (birgire)
 *  Version:       0.0.3
 */

add_action( 'pre_get_posts', function( $q )
{
    // Check the meta query:
    $mq = $q->get( 'meta_query' );

    if( empty( $mq ) )
        return;

    // Init:
    $marker = '___tmp_marker___'; 
    $rx     = [];

    // Collect all the sub meta queries, that use REGEXP, RLIKE or LIKE:
    foreach( $mq as $k => $m )                                    
    {
        if(    isset( $m['_key_compare'] )
            && in_array( strtoupper( $m['_key_compare'] ), [ 'REGEXP', 'RLIKE', 'LIKE' ] )
            && isset( $m['key'] )
        ) {
            // Mark the key with a unique string to secure the later replacements:
            $m['key'] .= $marker . $k; // Make the appended tmp marker unique

            // Modify the corresponding original query variable:
            $q->query_vars['meta_query'][$k]['key'] = $m['key'];

            // Collect it:
            $rx[$k] = $m;
        }
    }

    // Nothing to do:
    if( empty( $rx ) )
        return;

    // Get access the generated SQL of the meta query:
    add_filter( 'get_meta_sql', function( $sql ) use ( $rx, $marker )
    {
        // Only run once:
        static $nr = 0;         
        if( 0 != $nr++ )
            return $sql;

        // Modify WHERE part where we replace the temporary markers:
        foreach( $rx as $k => $r )
        {
            $sql['where'] = str_replace(
                sprintf(
                    ".meta_key = '%s' ",
                    $r['key']
                ),
                sprintf(
                    ".meta_key %s '%s' ",
                    $r['_key_compare'],
                    str_replace(
                        $marker . $k,
                        '',
                        $r['key']
                    )
                ),
                $sql['where']
            );
        }
        return $sql;
    });

});

我们在字符串替换的每个元键上添加唯一的标记。

请注意，这不支持正则表达式字符转义，如 ( 和\。

参考文献

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