在管理员列表发布屏幕中扩展搜索上下文

我创建了一个自定义帖子类型，并在其中附加了一些自定义字段。现在，我想搜索作者可以在自定义帖子列表屏幕（在管理后端）中执行的搜索，也可以在元字段中执行搜索，而不仅像往常一样查找标题和内容。

我可以在哪里挂接以及必须使用什么代码？

范例图片

斯特凡诺

我解决了通过在postmeta表上添加联接并更改where子句来过滤查询的问题。过滤WHERE子句的技巧（通常需要正则表达式search＆replace）在Codex上：

add_filter( 'posts_join', 'segnalazioni_search_join' );
function segnalazioni_search_join ( $join ) {
    global $pagenow, $wpdb;

    // I want the filter only when performing a search on edit page of Custom Post Type named "segnalazioni".
    if ( is_admin() && 'edit.php' === $pagenow && 'segnalazioni' === $_GET['post_type'] && ! empty( $_GET['s'] ) ) {    
        $join .= 'LEFT JOIN ' . $wpdb->postmeta . ' ON ' . $wpdb->posts . '.ID = ' . $wpdb->postmeta . '.post_id ';
    }
    return $join;
}

add_filter( 'posts_where', 'segnalazioni_search_where' );
function segnalazioni_search_where( $where ) {
    global $pagenow, $wpdb;

    // I want the filter only when performing a search on edit page of Custom Post Type named "segnalazioni".
    if ( is_admin() && 'edit.php' === $pagenow && 'segnalazioni' === $_GET['post_type'] && ! empty( $_GET['s'] ) ) {
        $where = preg_replace(
            "/\(\s*" . $wpdb->posts . ".post_title\s+LIKE\s*(\'[^\']+\')\s*\)/",
            "(" . $wpdb->posts . ".post_title LIKE $1) OR (" . $wpdb->postmeta . ".meta_value LIKE $1)", $where );
    }
    return $where;
}

Stefano的回答很好，但是缺少一个明显的子句：

function segnalazioni_search_distinct( $where ){
    global $pagenow, $wpdb;

    if ( is_admin() && $pagenow=='edit.php' && $_GET['post_type']=='segnalazioni' && $_GET['s'] != '') {
    return "DISTINCT";

    }
    return $where;
}
add_filter( 'posts_distinct', 'segnalazioni_search_distinct' );

添加上面的代码即可对其进行更新，并且不会重复。

这会起作用，

function custom_search_query( $query ) {
    $custom_fields = array(
        // put all the meta fields you want to search for here
        "rg_first_name",
        "rg_1job_designation"
    );
    $searchterm = $query->query_vars['s'];

    // we have to remove the "s" parameter from the query, because it will prevent the posts from being found
    $query->query_vars['s'] = "";

    if ($searchterm != "") {
        $meta_query = array('relation' => 'OR');
        foreach($custom_fields as $cf) {
            array_push($meta_query, array(
                'key' => $cf,
                'value' => $searchterm,
                'compare' => 'LIKE'
            ));
        }
        $query->set("meta_query", $meta_query);
    };
}
add_filter( "pre_get_posts", "custom_search_query");

答案1： 将此代码添加到功能文件中，并更改和添加更多在自定义帖子类型中使用的列名

function extend_admin_search( $query ) {

    // use your post type
    $post_type = 'document';
    // Use your Custom fields/column name to search for
    $custom_fields = array(
        "_file_name",
    );

    if( ! is_admin() )
        return;

    if ( $query->query['post_type'] != $post_type )
        return;

    $search_term = $query->query_vars['s'];

    // Set to empty, otherwise it won't find anything
    $query->query_vars['s'] = '';

    if ( $search_term != '' ) {
        $meta_query = array( 'relation' => 'OR' );

        foreach( $custom_fields as $custom_field ) {
            array_push( $meta_query, array(
                'key' => $custom_field,
                'value' => $search_term,
                'compare' => 'LIKE'
            ));
        }

        $query->set( 'meta_query', $meta_query );
    };
}

add_action( 'pre_get_posts', 'extend_admin_search' );

答案2：推荐 在功能文件中使用此代码，无需做任何更改

function cf_search_join( $join ) {
    global $wpdb;

    if ( is_search() ) {    
        $join .=' LEFT JOIN '.$wpdb->postmeta. ' ON '. $wpdb->posts . '.ID = ' . $wpdb->postmeta . '.post_id ';
    }

    return $join;
}
add_filter('posts_join', 'cf_search_join' );
function cf_search_where( $where ) {
    global $pagenow, $wpdb;

    if ( is_search() ) {
        $where = preg_replace(
            "/\(\s*".$wpdb->posts.".post_title\s+LIKE\s*(\'[^\']+\')\s*\)/",
            "(".$wpdb->posts.".post_title LIKE $1) OR (".$wpdb->postmeta.".meta_value LIKE $1)", $where );
    }

    return $where;
}
add_filter( 'posts_where', 'cf_search_where' );

function cf_search_distinct( $where ) {
    global $wpdb;

    if ( is_search() ) {
        return "DISTINCT";
    }

    return $where;
}
add_filter( 'posts_distinct', 'cf_search_distinct' );

这不是搜索，而是通过不同的值进行一些“选择”。

在文件functions-iworks-posts-filter.zip中，您有一个示例如何通过一些meta_key为常规帖子添加过滤器。我认为很容易转换。

几个答案中的代码版本修改了pre_get_posts中搜索的WP_Query的meta_query参数，不再搜索post_title。不幸的是，添加该功能可以在WP_Query中直接搜索帖子标题或OR元值而无需修改SQL，因为此问题的具体含义是：在搜索查询（'s'）中使用元查询（'meta_query'）

我在这里结合了一些技术来获得一个可以避免preg_replaces和过多的SQL修改的工作版本（我希望可以完全避免它）。唯一的缺点是搜索后，页面顶部的字幕文本显示为“的搜索结果”。我只是使用CSS将其隐藏为插件的自定义帖子类型。

/**
 * Extend custom post type search to also search meta fields
 * @param  WP_Query $query
 */
function extend_cpt_admin_search( $query ) {
  // Make sure we're in the admin area and that this is our custom post type
  if ( !is_admin() || $query->query['post_type'] != 'your_custom_post_type' ){
    return;
  }

  // Put all the meta fields you want to search for here
  $custom_fields = array(
    "your_custom_meta_field",
    "your_custom_meta_field2",
    "your_custom_meta_field3"
  );
  // The string submitted via the search form
  $searchterm = $query->query_vars['s'];

  // Set to empty, otherwise no results will be returned.
  // The one downside is that the displayed search text is empty at the top of the page.
  $query->query_vars['s'] = '';

  if ($searchterm != ""){
    // Add additional meta_query parameter to the WP_Query object.
    // Reference: https://codex.wordpress.org/Class_Reference/WP_Query#Custom_Field_Parameters
    $meta_query = array();
    foreach($custom_fields as $cf) {
      array_push($meta_query, array(
        'key' => $cf,
        'value' => $searchterm,
        'compare' => 'LIKE'
      ));
    }
    // Use an 'OR' comparison for each additional custom meta field.
    if (count($meta_query) > 1){
      $meta_query['relation'] = 'OR';
    }
    // Set the meta_query parameter
    $query->set('meta_query', $meta_query);


    // To allow the search to also return "OR" results on the post_title
    $query->set('_meta_or_title', $searchterm);
  }
}
add_action('pre_get_posts', 'extend_cpt_admin_search');



/**
 * WP_Query parameter _meta_or_title to allow searching post_title when also
 * checking searching custom meta values
 * https://wordpress.stackexchange.com/questions/78649/using-meta-query-meta-query-with-a-search-query-s
 * https://wordpress.stackexchange.com/a/178492
 * This looks a little scary, but basically it's modifying the WHERE clause in the 
 * SQL to say "[like the post_title] OR [the existing WHERE clause]"
 * @param  WP_Query $q
 */
function meta_or_title_search( $q ){
  if( $title = $q->get( '_meta_or_title' ) ){
    add_filter( 'get_meta_sql', function( $sql ) use ( $title ){
      global $wpdb;

      // Only run once:
      static $nr = 0;
      if( 0 != $nr++ ) return $sql;

      // Modified WHERE
      $sql['where'] = sprintf(
          " AND ( (%s) OR (%s) ) ",
          $wpdb->prepare( "{$wpdb->posts}.post_title LIKE '%%%s%%'", $title),
          mb_substr( $sql['where'], 5, mb_strlen( $sql['where'] ) )
      );

      return $sql;
    });
  }
}
add_action('pre_get_posts', 'meta_or_title_search');