Exclude post ID from wp_query

Question

How can I exclude one specific post from a WP_Query query? (For example, show all posts apart from a post with the ID 278)

I've tried the post__not_in argument but it just removes all posts..

Any help would be great.

Here is my current query

<?php
    $temp = $wp_query;
    $wp_query= null;
    $wp_query = new WP_Query(array(
        'post_type' => 'case-study',
        'paged' => $paged,
    ));
    while ($wp_query->have_posts()) : $wp_query->the_post();
?>

Thanks

Answer 1

I suppose this was heavy, but to answer your original question, I've collected all of the posts id's in an array in the first loop, and excluded those posts from the second loop using 'post__not_in' which expects an array of post id's

<?php
$args1 = array('category_name' => 'test-cat-1', 'order' => 'ASC');
$q1 = new WP_query($args);
if($q1->have_posts()) :
$firstPosts = array();
    while($q1->have_posts()) : $q1->the_post();
        $firstPosts[] = $post->ID; // add post id to array
        echo '<div class="item">';
        echo "<h2>" . get_the_title() . "</h2>";
        echo "</div>";
    endwhile;
endif;
/****************************************************************************/
// array of post id's collected in first loop, can now be used as value for the 'post__not_in' parameter in second loops query $args
$args2 = array('post__not_in' => $firstPosts, 'order' => 'ASC' );
$q2 = new WP_query($args2);
if($q2->have_posts()) :
    while($q2->have_posts()) : $q2->the_post();
        echo '<div class="item">';
        echo "<h2>" . get_the_title() . "</h2>";
        echo "</div>";
    endwhile;
endif;
?>

The first loop displays all posts in a category, and collects the post id's into an array.

The second loop displays all posts, excluding posts from the first loop.

Answer 2

The parameter you are looking for is post__not_in (kaiser has a typo in his answer). So the code could be like:

<?php
$my_query = new WP_Query(array(
    'post__not_in' => array(278),
    'post_type' => 'case-study',
    'paged' => $paged,
));
while ($my_query->have_posts()) : $my_query->the_post(); endwhile;

WP_Query post__not_in documentation

Answer 3

You have to define the post__not_in arg as array. Even for a single value. And please don't overwrite global core variables with temporary stuff.

<?php
$query = new WP_Query( array(
    'post_type'    => 'case-study',
    'paged'        => $paged,
    'post__not_in' => array( 1, ),
) );
if ( $query->have_posts() ) {
while ( $query->have_posts() ) {
    $query->the_post();

    // do stuff

} // endwhile;
} // endif;
?>

Answer 4

Alternative codes;

Exclude category posts

<?php
add_action('pre_get_posts', 'exclude_category_posts');
function exclude_category_posts( $query ) {
    if($query->is_main_query() && $query->is_home()) {
        $query->set('cat', array( -22, -27 ));
    }
}

Remove posts from homepage page

<?php
add_action('pre_get_posts', 'wpsites_remove_posts_from_home_page');
function wpsites_remove_posts_from_home_page( $query ) {
    if($query->is_main_query() && $query->is_home()) {
        $query->set('category__not_in', array(-1, -11));
    }
}