Listing posts with a value in a custom field

Question

I read several posts and stack exchange answers but still cannot put the code together to work.

I read the post Query posts by custom fields

I have posts with custom fields, lets say "publisher" with a value "IBM".

I have a page listing all the values for the custom field "publisher".

I want IBM to link to a search result for all the posts with this meta_value.

My index.php page begins with

        <?php while(have_posts()){
        the_post(); ?>

I need to send to index.php the request with meta_key and meta_value, add a filter to the query and list the results, but I don't know how to "stitch" everything so it will do what I want.

Thanks.

Answer 1

Assuming that this meta is for the post type "post" you could create a loop in two ways, get_posts or WP_Query.
I also prefer the meta_query property over the meta_value and meta_key, because it adds the option to add more meta queries quicker as the array already exists.

The get_posts method

$posts = get_posts([
    'post_type'      => 'post',
    'post_status'    => 'publish',
    'posts_per_page' => -1,
    'meta_query'     => [
        [
            'key'     => 'publisher',
            'value'   => 'IBM',
        ]
    ]
]);

foreach ($posts as $post) {
    // your code here
}

The WP_Query method

$posts = new WP_Query([
    'post_type'      => 'post',
    'post_status'    => 'publish',
    'posts_per_page' => -1,
    'meta_query'     => [
        [
            'key'     => 'publisher',
            'value'   => 'IBM',
        ]
    ]
]);

if ($posts->have_posts()) {
    while ($posts->have_posts()) {
        the_post();

        // your code here
    }
}

The best resource for understanding how this works is the WP_Query documentation