按元值排序，先亲，然后自由

在我辞职之前,只有一个笔记,从不(我的重点是)利用 query_posts 创建自定义查询

注意:此功能并非供插件或主题使用.如后面所述,有更好的,性能更高的选项可以更改主查询. query_posts()是通过将页面主查询替换为查询的新实例来修改页面主查询的过于简单和有问题的方法.它效率低下(重新运行SQL查询),在某些情况下(尤其是在处理帖子分页时,通常会完全失败).

而是使用 WP_Query 或 get_posts 创建自定义查询,但仅无法使用 pre_get_posts 修改主查询.有关更多信息,请查看这篇文章

假设您的meta_key(请注意,只有两个值:请注意:出于测试目的,我使用了自己的meta键,您应该将其替换为自己的 ),即pro和free,您只需检索具有此特定meta_key的帖子即可.您的查询将如下所示:

 $args = [
    'meta_key'          => 'packages',
    'orderby'           => 'rand',
    'posts_per_page'    => 5,
];

$the_query = new WP_Query( $args );
 

但是,如果您拥有的值不止于这两个值,那么您将需要调整查询以包含meta_value,然后使用meta_compare参数.调整后的查询将变为:

 $args = [
    'meta_key'          => 'packages',
    'meta_value'        => 'free, pro',
    'orderby'           => 'rand',
    'meta_compare'      => 'IN',
    'posts_per_page'    => 5,
];
 

( PS！在继续之前,您应该注意orderby参数在版本4.0中已更改,但这在此实例中不起作用.

太好了,您现在将有5条帖子是随机检索的,其meta_value为pro或free

现在我们需要对它们进行排序.最好的解决方案是利用 usort 根据帖子的meta_value的值对meta_value中返回的帖子数组进行排序.然后,您需要取消设置$the_query->posts,然后使用重新排序的post数组将其重置.

这是完整的代码:

 <?php
$args = [
    'meta_key'          => 'packages',
    'meta_value'        => 'free, pro',
    'orderby'           => 'rand',
    'meta_compare'      => 'IN',
    'posts_per_page'    => 5,
];

$the_query = new WP_Query( $args );
$post_metas = $the_query->posts;

usort( $post_metas, function( $a, $b ){
    $a = get_post_meta( $a->ID , 'packages', true ) ;
    $b = get_post_meta( $b->ID, 'packages', true ) ;

    if ( $a == $b ) {
        return 0;
    }
        return ( $a > $b ) ? -1 : 1;
    }
);

unset($the_query->posts);
$the_query->posts = $post_metas;

if ( $the_query->have_posts() ) {
    echo '<ul>';
    while ( $the_query->have_posts() ) {
        $the_query->the_post();

        echo '<li>' . get_post_meta( get_the_ID(), 'packages', true ). '</br>' . get_the_title() . '</li>';

    }
    echo '</ul>';
} 
wp_reset_postdata();
?>
 

您只需要调整查询变量以适合您的需求,并调整循环以显示所需内容

尽管这不是实现此目标的唯一方法,您还可以将排序功能移至functions.php并专门针对此自定义查询

Before I fire away, just one note, NEVER (my emphasis) make use of query_posts to create custom queries

Note: This function isn't meant to be used by plugins or themes. As explained later, there are better, more performant options to alter the main query. query_posts() is overly simplistic and problematic way to modify main query of a page by replacing it with new instance of the query. It is inefficient (re-runs SQL queries) and will outright fail in some circumstances (especially often when dealing with posts pagination).

Rather make use of WP_Query or get_posts to create custom queries, but ONLY if you can't modify the main query with pre_get_posts. For more info, check out this post

Assuming that there are only two values for your meta_key (PLEASE NOTE: For testing purposes, I have used my own meta key, you should replace this with your own), namely pro and free, you can just retrieve posts that has this specific meta_key. Your query will then look something like this:

$args = [
    'meta_key'          => 'packages',
    'orderby'           => 'rand',
    'posts_per_page'    => 5,
];

$the_query = new WP_Query( $args );

If you however have more values than just these two, then you will need to adjust your query to include the meta_value and then make use of the meta_compare parameter. Your adjusted query will then become:

$args = [
    'meta_key'          => 'packages',
    'meta_value'        => 'free, pro',
    'orderby'           => 'rand',
    'meta_compare'      => 'IN',
    'posts_per_page'    => 5,
];

(PS! Before I go on, you should note that the orderby parameter has changed in version 4.0, but this will not work in this instance.

Great, you will now have 5 posts that was retrieved randomly which has either a meta_value of pro or free

Now we need to sort them. The best possible solution is to make use of usort to sort the returned array of posts in $the_query->posts according to the value of the posts meta_value. You will then need to unset $the_query->posts and then reset it with the reordered post array.

Here is the complete code:

<?php
$args = [
    'meta_key'          => 'packages',
    'meta_value'        => 'free, pro',
    'orderby'           => 'rand',
    'meta_compare'      => 'IN',
    'posts_per_page'    => 5,
];

$the_query = new WP_Query( $args );
$post_metas = $the_query->posts;

usort( $post_metas, function( $a, $b ){
    $a = get_post_meta( $a->ID , 'packages', true ) ;
    $b = get_post_meta( $b->ID, 'packages', true ) ;

    if ( $a == $b ) {
        return 0;
    }
        return ( $a > $b ) ? -1 : 1;
    }
);

unset($the_query->posts);
$the_query->posts = $post_metas;

if ( $the_query->have_posts() ) {
    echo '<ul>';
    while ( $the_query->have_posts() ) {
        $the_query->the_post();

        echo '<li>' . get_post_meta( get_the_ID(), 'packages', true ). '</br>' . get_the_title() . '</li>';

    }
    echo '</ul>';
} 
wp_reset_postdata();
?>

You will just need to adjust the query variables to suit your needs and also adjust the loop to display what is needed

This is not the only way to achieve it though, you can also move your sorting function to your functions.php and specifically target this custom query

您需要通过meta_key而不是meta_value进行查询:

  $query_string . '&meta_key=name_of_key_that_stores_free_or_pro&orderby=meta_value_num'
 

You need to query by the meta_key instead of meta_value:

 $query_string . '&meta_key=name_of_key_that_stores_free_or_pro&orderby=meta_value_num'