exclude ids through post__not_in

Question

I am trying to make a function and exclude in the post query that way im able to define the id's in my function but it is only excluding 1 post instead of the 4 it is returning.

any suggestions on how I can go about successfully executing this?

function in the functions.php file

function slider_exclude(){
    $exclude_query = query_posts(array('showposts' => 4, 'cat' => 'news',));
    foreach($exclude_query as $post_ids){
        return $post_ids->ID.',';
    }
}

my loop

$args = array(
    'post__not_in' => array(slider_exclude()),
    'post_type' => 'post',
    'posts_per_page' => 15,
    'paged' => ( get_query_var('paged') ? get_query_var('paged') : 1)
);
query_posts($args);

Answer 1

Your PHP is wrong.

function slider_exclude(){
    $exclude_query = query_posts(array('showposts' => 4, 'cat' => 'news',));
    foreach($exclude_query as $post_ids){
        return $post_ids->ID.',';
    }   
}

Looks like you are trying to build a comma delimited string but that isn't how return works. When that foreach hits the return the function returns-- it ends. Nothing else gets processed.

You need to be building and returning an array, from the look of it.

function slider_exclude(){
    $ret = array();
    $exclude_query = query_posts(array('showposts' => 4, 'cat' => 'news',));
    foreach($exclude_query as $post_ids){
        $ret[] = $post_ids->ID;
    } 
    return $ret;  
}

Then you will have trouble with this line:

'post__not_in' => array(slider_exclude()),

Because now you will have a nested array. Do this:

'post__not_in' => slider_exclude(),

Or better:

$args = array(
    'post_type' => 'post',
    'posts_per_page' => 15,
    'paged' => ( get_query_var('paged') ? get_query_var('paged') : 1)
);
$exclude = slider_exclude();
if (!empty($exclude)) {
    $args['post__not_in'] = $exclude;
}
query_posts($args);

That will only add the post_not_in condition if there is something to exclude.