Custom field to array?

Question

I have a posts query that queries posts by ID but want to select those posts by enetering a custom field. Here is the query and where I want to put the custom field:

$query_args = array('post_type'=>'post', 'post_status'=>'publish', 'include' => '483,454, CUSTOM FIELD HERE', 'orderby' => 'date', 'order' => 'ASC');

More info: Custom field is listids and passed in include. But doesn't work.

<?php
&listids = get_post_meta($post->ID, 'list_array', true);
$query_args = array('post_type'=>'post', 'post_status'=>'publish', 'include' => 'echo $listids;', 'orderby' => 'date', 'order' => 'ASC');
$query_posts = get_posts($query_args);
$last_query = end($query_posts);
foreach ($query_posts as $post) : setup_postdata($post); ?> 

Answer 1

I will assume that you(or users) will enter post ids into a posts custom field, comma separated, eg: 11,13,34,54 OR 11, 13, 34, 54.

Then all you need to do is get the custom field value for the loaded post, explode the custom field value by comma(,): and, then you'll have a nice array to pass into the include parameter. Here is an example showing the important pieces:

<?php
    $postIds = get_post_meta($post->ID, 'postIds', true); // get custom field value
    $arrayIds = explode(',', $postIds); // explode value into an array of ids
    if(count($arrayIds) <= 1) // if array contains one element or less, there's spaces after comma's, or you only entered one id
    {
        if( strpos($arrayIds[0], ',') !== false )// if the first array value has commas, there were spaces after ids entered
        {
            $arrayIds = array(); // reset array
            $arrayIds = explode(', ', $postIds); // explode ids with space after comma's
        }

    }

    $args = array(
        'include' => $arrayIds // pass array of ids into `include` parameter
    );
    ...
?>